Dissertations / Theses on the topic 'Audio Amplifiers'
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Cartwright, Justin Adam. "A novel technique for harmonic cancellation in class D amplifiers a thesis presented to the faculty of the Graduate School, Tennessee Technological University /." Click to access online, 2009. http://proquest.umi.com/pqdweb?index=2&did=1759989201&SrchMode=1&sid=1&Fmt=6&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1250263495&clientId=28564.
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Quibell, Jason. "Digital control of a Class-D Audio Amplifier." Thesis, Cape Peninsula University of Technology, 2011. http://hdl.handle.net/20.500.11838/1116.
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Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2011Modern technologies have led to extensive digital music reproduction and distribution. It is fitting then that digital audio be amplified directly from its source rather than being converted to an analogue waveform before amplification. The benefits of using a digital controller for audio processing include being able to easily reconfigure the system and to add additional functions at a later stage.Digital audio is primarily stored as Pulse Code Modulation (PCM) while Pulse Width Modulation (PWM) is the most popular scheme used to drive a class-D amplifier. The class-D amplifier is selected in many applications due to its very high energy efficiency. Conventional PCM to PWM conversion is inherently nonlinear. Various interpolation schemes are presented in this research project which help to address the nonlinearity.Digitally generated PWM has a limited resolution which is constrained by the system clock. This thesis presents noise shaping techniques which increase the effective resolution of the PWM process without having to use an excessively high system clock. Noise shaping allows a low resolution modulator to be used to reproduce high resolution audio.
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BURRA, RAVIKANTH. "DESIGN METHODOLOGIES OF CLASS D AUDIO SWITCHING AMPLIFIERS." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1123767048.
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Ginart, Antonio. "Single ended switching analog audio amplifier with dead zone." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/15767.
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Jacobs, Deon. "Digital pulse width modulation for Class-D audio amplifiers." Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/1574.
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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2006.Digital audio data storage mediums have long been used within the consumer market. Today, because of the advancement of processor clock speeds and increased MOSFET switching capabilities, digital audio data formats can be directly amplified using power electronic inverters. These amplifiers known as Class-D have an advantage over there analogue counterparts because of their high efficiency. This thesis deals with the signal processing algorithms necessary to convert the digital audio data obtained from the source to a digital pulse width modulated signal which controls a full bridge inverter for audio amplification. These algorithms address difficulties experienced in the past which prevented high fidelity digital pulse width modulators to be implemented. The signal processing algorithms are divided into modular blocks, each of which are defined in theory, designed and simulated in Matlab® and then implemented within VHDL firmware. These firmware blocks are then used to realize a Class-D audio amplifier.
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Andracek, Julie. "Increasing learning in kindergarten classrooms through use of a sound amplification system." Online version, 2009. http://www.uwstout.edu/lib/thesis/2009/2009andracekj.pdf.
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Geertsema, Salomè. "Persoonlike klankversterking as hulpmiddel vir 'n onderwyser met funksionele stemprobleme." Pretoria : [s.n.], 2004. http://upetd.up.ac.za/thesis/available/etd-10042005-124844.
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Mosely, Iain David. "The design of high efficiency power amplifiers for in-car audio use." Thesis, University of Sheffield, 2000. http://etheses.whiterose.ac.uk/14795/.
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Switched mode, Class-D power amplification allows for high efficiency power amplification of an audio signal. This thesis investigates its application to high power car audio systems where there is a demand for efficient high power amplification. Examination of the present car audio power amplifiers, which comprise a switched mode power supply combined with a linear output stage, has shown that there is significant scope for improvement in efficiency and power density. A novel power stage in which the attributes of a switched-mode power supply and full bridge output stage is presented. It is demonstrated that elimination of the intermedjate DC supply results in an amplifier which has a significantly lower part count, size and cost compared to conventional designs. Two different modulation schemes are explored (PWM and PDM) with a view to finding the most suitable for the new power stage. The theoretical performances of the modulators are verified by practical measurements. The design of high order DeltaSigma modulators is difficult as they show unstable behaviour and an alternative design methodology has been presented to ease this task. The mechanisms which introduce distortion in a practical amplifier are discussed, and for the case of a PWM driven output stage, a new model is presented to predict the effect of dead time on harmonic distortion. This form of distortion is shown to be the dominant cause of open loop non-linearity. The use of feedback is also investigated and yields a factor of 20 improvement in amplifier total harmonic distortion . The design throughout has been supported with practical results and these have illustrated the importance for careful circuit layout in high frequency switching systems.
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Jha, Nand Kishore. "Design of a complementary silicon-germanium variable gain amplifier." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24614.
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Hanusaik, Linda Irene. "An evaluation of user performance with inductive coupling of hearing aids and telephone receivers incorporating receiver amplification." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/29863.
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Previous research has shown the benefit obtained by hard of hearing people when using inductive means (T-switch) to couple their hearing aids to telephone receivers. Benefit provided by receiver amplification in the telephone handset has also been shown. Informal surveys of hard of hearing people indicate that many of them use telephones having a dual capability: magnetic coupling and receiver amplification. The objective of this investigation was to study user performance with this dual capability. In particular, the effect of receiver amplification on the speech perception ability (as measured by R-SPIN test items) of 10 hard of hearing subjects using inductive means to couple their hearing aid to a telephone receiver was examined under both good and poor telephone line conditions. The influence of the predictability of the speech material presented was also investigated by noting any difference between the subjects' performance on high predictability items and performance on low predictability items (of the R-SPIN test).
Results showed that the use of receiver amplification in conjunction with inductive coupling significantly improved the subjects' speech perception scores. Not surprisingly, good telephone line conditions also significantly improved the subjects' scores. Improvement due to receiver amplification was noted, irrespective of line conditions. Similarly, improvement due to good line conditions was observed, irrespective of whether amplification was used or not. Both receiver amplification and good line conditions had significant and positive effects on both low predictability and high predictability scores. We conclude that with speech either in or out of context, receiver amplification will be of benefit to those who use inductive coupling. Clinical implications and recommendations are discussed.Medicine, Faculty of
Audiology and Speech Sciences, School of
Graduate
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Puidokas, Vytenis. "Design and Research on Sigma-Delta Digital-to-Analog Converters for Audio Power Amplifiers." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20111220_133108-90590.
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The dissertation investigates the issues of analyzing a digital Sigma-Delta digital-to-analog converter (DAC) for audio power amplifiers. The main objects of research include a digital Sigma-Delta audio power DAC, improvement of its structure and an experimental research. The primary purpose of the dissertation is to suggest methods for improvement the structure of digital Sigma-Delta audio power DAC interpolator and the converter analysis.Disertacijoje nagrinėjami Sigma-Delta skaitmeniniai-analoginiai (skaičiaus-analogo, SA) keitikliai garso galios stiprintuvams. Pagrindinis tyrimų objektas – skaitmeninis Sigma-Delta garso galios SA keitiklis, jo sandaros tobulinamas bei eksperimentinis tyrimas. Disertacijos tikslas – pasiūlyti skaitmeninio Sigma-Delta garso galios SA keitiklio interpoliatoriaus struktūros tobulinimo bei keitiklio tyrimo metodus.
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Bengtsson, Fredrik, and Rikard Berglund. "Digital compensation of distortion in audio systems." Thesis, Linköping University, Department of Electrical Engineering, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-56392.
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The advancements of computational power in low cost FPGAs are giving the opportunityto implement real-time compensation of loudspeakers and audio systems. The need for expensive commercial audio systems is reduced when the fidelity ofmuch cheaper audio systems easily can be improved by real-time compensation. The topic of this thesis is to investigate and evaluate methods for digital compensationof distortion in audio systems. More specifically, a VHDL module isimplemented to, when necessary, alleviate the problem of drastically deterioratingfidelity of the bass appearing when the input power is too high.
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Melo, João Luís Alvernaz de. "Design of a Continuous-Time (CT) Sigma-Delta modulator for class D audio power amplifiers." Master's thesis, Faculdade de Ciências e Tecnologia, 2010. http://hdl.handle.net/10362/13154.
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Leitão, Pedro Miguel Vicente. "Design of a power output stage for a class D audio power amplifier based on an 1.5-bit ∑ ∆ M." Master's thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/10229.
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Nasir, Nasir. "Development of novel low noise switch-mode power supply designs for high fidelity audio power amplifiers." Thesis, Bournemouth University, 2017. http://eprints.bournemouth.ac.uk/29795/.
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Today, linear power supplies are widely used to provide the supply voltage rail to an audio amplifier and are considered bulky, inefficient and expensive due to the presence of various components. In particular, the typical requirements of linear designs call for physically large mains transformers, energy storage/filtering inductors and capacitors. This imposes a practical limit to the reduction of weight in audio power systems. In order to overcome these problems, Switch-mode Power Supplies (SMPS) incorporate high speed switching transistors that allow for much smaller power conversion and energy storage components to be employed. In addition the low power dissipation of the transistors in the saturated and off states results in higher efficiency, improved voltage regulation and excellent power factor ratings. The primary aim of this research was to develop and characterize a novel low noise switch mode power supply for an audio power amplifier. In this thesis, I proposed a novel balancing technique to optimize the design of SMPS that elevate the performance of converter and help to enhance the efficiency of power supply through high speed switching transistors. In fact, the proposed scheme mitigates the noise considerably in various converter topologies through different mechanisms. To validate the proposed idea, the technique is applied to different converters e.g; PFC boost converter, flyback converter and full-bridge converter. The performance of audio amplifier is evaluated using designed SMPS to compare with existing linear power supply. On the basis of experimental results, the decision has been made that the proposed balanced SMPS solution is as good as linear solution. Due to novelty and universality of balancing technique, it can provide a new path for researchers in this field to utilize the SMPS in all other audio devices by further enhancing its efficiency and reducing system noise.
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Thakkar, Darshan Suresh, and darshanst@gmail com. "FPGA Implementation of Short Word-Length Algorithms." RMIT University. Electrical and Computer Engineering, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080806.140908.
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Short Word-Length refers to single-bit, two-bit or ternary processing systems. SWL systems use Sigma-Delta Modulation (SDM) technique to express an analogue or multi-bit input signal in terms of a high frequency single-bit stream. In Sigma-Delta Modulation, the input signal is coarsely quantized into a single-bit representation by sampling it at a much higher rate than twice the maximum input frequency viz. the Nyquist rate. This single-bit representation is almost exclusively filtered to remove conversion quantization noise and sample decimated to the Nyquist frequency in preparation for traditional signal processing. SWL algorithms have a huge potential in a variety of applications as they offer many advantages as compared to multi-bit approaches. Features of SWL include efficient hardware implementation, increased flexibility and massive cost savings. Field Programmable Gate Arrays (FPGAs) are SRAM/FLASH based integrated circuits that can be programmed and re-programmed by the end user. FPGAs are made up of arrays of logic gates, routing channels and I/O blocks. State-of-the-art FPGAs include features such as Advanced Clock Management, Dedicated Multipliers, DSP Slices, High Speed I/O and Embedded Microprocessors. A System-on-Programmable-Chip (SoPC) design approach uses some or all the aforementioned resources to create a complete processing system on the device itself, ensuring maximum silicon area utilization and higher speed by eliminating inter-chip communication overheads. This dissertation focuses on the application of SWL processing systems in audio Class-D Amplifiers and aims to prove the claims of efficient hardware implementation and higher speeds of operation. The analog Class-D Amplifier is analyzed and an SWL equivalent of the system is derived by replacing the analogue components with DSP functions wherever possible. The SWL Class-D Amplifier is implemented on an FPGA, the standard emulation platform, using VHSIC Hardware Description Languages (VHDL). The approach is taken a step forward by adding re-configurability and media selectivity and proposing SDM adaptivity to improve performance.
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Koeslag, Francois. "A detailed analysis of the imperfections of pulsewidth modulated waveforms on the output stage of a class D audio amplifier." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/3972.
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Thesis (PhD (Electrical and Electronic Engineering))--University of Stellenbosch, 2009.Although the Class D topology offers several advantages, its use in audio amplification has previously been limited by the lack of competitiveness in fidelity compared to its linear counterparts. During the past decade, technological advances in semiconductor technology have awakened new interest since competitive levels of distortion could now be achieved. The output stage of such an amplifier is the primary limiting factor in its performance. In this dissertation, four non-ideal effects existing in this stage are identified and mathematically analysed. The analytical analysis makes use of a well-established mathematical model, based on the double Fourier series method, to model the imperfections introduced into a naturally sampled pulsewidth modulated waveform. The analysis is complemented by simulation using a strategy based on Newton’s numerical method. The theory is verified by a comparison between the analytical-, simulated- and experimental results.
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Mbaye, Amadou. "Linéarisation des amplificateurs de puissance large-bande pour des applications de communications tactiques et de diffusion audio ou vidéo numérique." Thesis, Paris Est, 2015. http://www.theses.fr/2015PEST1021/document.
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L'amplificateur de puissance est le module le plus critique dans les équipements de communication radio. Il détermine la qualité de la liaison par sa linéarité et a une contribution conséquente dans la consommation de l'émetteur ; environ 60% de l'énergie consommée est consacré à l'amplification. Il est donc crucial de le faire fonctionner avec un rendement énergétique élevé. Cependant, ces deux spécifications principales de l'amplificateur que sont la linéarité et le rendement énergétique sont antagoniques. Par conséquent, la conception d'un module d'amplification de puissance suppose de trouver un compromis entre la linéarité et le rendement. L'optimisation de ce compromis est la raison d'être des techniques de linéarisation d'amplificateurs et d'amélioration du rendement, parmi lesquelles la prédistorsion numérique (DPD) et les techniques de réduction du PAPR du signal (CFR).Le cœur de cette thèse est la linéarisation d'amplificateurs RF haute-puissance et large-bande par prédistorsion numérique (DPD). Dans ces travaux, nous abordons trois problématiques liées à la prédistorsion et qui constituent des verrous technologiques importants. Le premier aspect concerne l'implémentation de la prédistorsion numérique dans un contexte multi-bande où le signal à linéariser comporte plusieurs formes d'ondes, situées à des fréquences différentes. La seconde problématique est l'utilisation conjointe de la prédistorsion avec une technique de CFR. Dans la majorité des applications haute-puissance, les techniques de DPD et de CFR sont présentes de manière complémentaire, cependant elles sont utilisées de façon autonome et disjointe. Celles-ci gagneraient en performances de linéarisation en étant implémentées de manière plus concertée. . Le dernier thème abordé par cette thèse est l'effet des désadaptations d'impédance de l'antenne sur le mode de fonctionnement de l'amplificateur. La variation de l'impédance d'antenne entraine des réflexions de signal vers l'amplificateur qui modifient ses spécifications de linéarité et de rendement. Nous améliorons la linéarité du système DPD + AP, lorsque l'amplificateur est soumis à des variations de l'impédance à sa charge, grâce à une correction adaptative de gainPower amplifier is one of the most critical element within radiocommunications systems. The PA is their main source of nonlinearities and it has a great contribution on the emitter's power consumption. Running the PA with highest power efficiency is thus as crucial as having it linear for a good communication quality. However these two specifications of the PA are antagonistic and PA manifacturers need to find a compromise between linearity and power efficiency. Digital Predistortion (DPD) and Crest factor Reduction techniques are intended to improve power efficiency while preserving linearity or inversely. Linearization of wideband RF power amplifiers using Digital Predistortion is the focus of this thesis. Three DPD issues are investigated in these works. The first issue deals with multiband linearization where signals with various waveforms located at different frequency bands are amplified. The second objective of this thesis is to study a concurrent DPD/CFR systems based on an automatic estimation of the necessary CFR gain. The last part of this dissertation deals with PA linearization under antenna load variations. Indeed, the impedance of antenna may vary because of electromagnetic objects that are present in its vicinity. Those impedance variations may instigate signal reflections toward the PA, that modify some of its main specifications (linearity, delivered power and efficiency). Our goal in this field is to preserve DPD linearization performances under antenna load mismatch
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SUN, JINGJIE, and YINGJUN CHEN. "Audio power amplifier design." Thesis, Högskolan i Gävle, Avdelningen för elektronik, matematik och naturvetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-9761.
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The audio power amplifier is used to amplify low-power audio signals to a level that can be suitable for driving the loudspeakers. Thus the audio power amplifier becomes a kind of essential part in the electronics that could make sounds. In this thesis, a good performance audio power amplifier with tonality control is designed. It consists of three parts: pre-amplifier unit, the tonality control unit and the power amplifier unit. In the pre-amplifier unit, a TL071CP operational amplifier is applied, to amplify the low signal to be suitable for the tonality control unit. For the tonality control unit, a filter is used to achieve bass and treble control, resulting in different frequency response. In the last part, the low voltage power amplifier LM386N-1 is used. The results of simulation in Multisim show a good output waveform and different frequency response with the tonality control. Also the pure sound can be heard by ear clearly. The good simulation result offers the encouragement to build the circuit on the board and do the measurement. The measured results show a good output waveform, the output power 256mW, THD 4.7%, the maximum voltage gain 40 etc. Meanwhile, sound can be heard by ear clearly with the tonality control. Judging from the results, the audio power amplifier is designed successfully.
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SALIMATH, ARUNKUMAR. "SIMO DC-DC Converter for Automotive Audio Amplifier." Doctoral thesis, Università degli studi di Pavia, 2018. http://hdl.handle.net/11571/1214878.
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Modern auto industry is ubiquitously deploying electronic systems for several applications like control, infotainment and security among others in the vehicles. Automotive infotainment is a key segment for the growth of automotive electronics as the vehicles, both light and heavy, require radio, video, navigation-assistance and telematics systems for both entertainment and networking.
Like any battery-operated systems, the automotive infotainment systems are required to provide high efficiency. One major constituent of in-vehicle infotainment being the radio, improving the overall efficiency of a car radio system is emphasized by the industry. In the state-of-the-art, the automotive audio amplifiers severely lack efficiency offering <40% in the mute condition. This research targets to improve the overall efficiency of an audio amplifier in a car radio by power supplying efficiently.
A Single Inductor Multiple Output dc-dc converter is explored as a supply voltage generator for an automotive audio amplifier in a car radio. The presence of line and load fluctuations, together with wide range of operating temperatures, in the automotive environment pose major challenge to the voltage regulation. A systematic feasibility study and analysis of specifications brought out the equivalence between the target SIMO converter and a non-inverting buck-boost SISO converter. Based on the equivalence, equilibrium and small signal models for the SIMO converter are developed. A voltage-mode, error-based controller is designed to control the dynamics of the converter. A novel power switching stage is conceived to generate the supplies required in a multi-channel class-D power amplifier. The switch
configuration is critical due the absence of a well-defined reference to one of the regulated outputs and the effect of package parasitics at high switching frequencies. The converter is charged synchronously and discharged quasi-synchronously to the loads. The switches are configured and driven optimally based on extensive simulations in the presence of package models to suppress the switching noise. In order to reduce the EM interference in the AM band of interest, the SIMO converter is switched at permissible high frequencies based on the EMI mask.
The automotive-class SIMO dc-dc converter is designed and integrated with a state-of-the-art class-D audio amplifier using 110nm BCD process technology offered by STMicroelectronics. The SIMO converter provides a battery tracking boost and a ground referred buck outputs for driving the class-D power stage. A unique feature of the converter is the generation of a floating voltage across half battery to supply the DSP core of the amplifier. The converter starts-up as boost converter alone followed entering boost-assisted SIMO converter mode. The active area occupied is 2.5mm2. The switching frequency is 2-2.4MHz. The converter has a load capability to drive up to 4 channels of a class-D power stage with peak efficiency of 86% and peak output power of 2.8W. The ripple voltage on the regulated outputs is below 25mV. The SIMO converter is able to sustain the automotive battery crank and dump conditions across the battery variation range of 4.5-27V. A line regulation of 6.3-16.2mV/V and a load regulation of 0.16mV/mA are provided by the SIMO converter. In the presence of wide range of battery variations, the SIMO converter incorporates all the necessary protections circuits and under/over voltage interrupts through I2C communication.Modern auto industry is ubiquitously deploying electronic systems for several applications like control, infotainment and security among others in the vehicles. Automotive infotainment is a key segment for the growth of automotive electronics as the vehicles, both light and heavy, require radio, video, navigation-assistance and telematics systems for both entertainment and networking. Like any battery-operated systems, the automotive infotainment systems are required to provide high efficiency. One major constituent of in-vehicle infotainment being the radio, improving the overall efficiency of a car radio system is emphasized by the industry. In the state-of-the-art, the automotive audio amplifiers severely lack efficiency offering <40% in the mute condition. This research targets to improve the overall efficiency of an audio amplifier in a car radio by power supplying efficiently. A Single Inductor Multiple Output dc-dc converter is explored as a supply voltage generator for an automotive audio amplifier in a car radio. The presence of line and load fluctuations, together with wide range of operating temperatures, in the automotive environment pose major challenge to the voltage regulation. A systematic feasibility study and analysis of specifications brought out the equivalence between the target SIMO converter and a non-inverting buck-boost SISO converter. Based on the equivalence, equilibrium and small signal models for the SIMO converter are developed. A voltage-mode, error-based controller is designed to control the dynamics of the converter. A novel power switching stage is conceived to generate the supplies required in a multi-channel class-D power amplifier. The switch configuration is critical due the absence of a well-defined reference to one of the regulated outputs and the effect of package parasitics at high switching frequencies. The converter is charged synchronously and discharged quasi-synchronously to the loads. The switches are configured and driven optimally based on extensive simulations in the presence of package models to suppress the switching noise. In order to reduce the EM interference in the AM band of interest, the SIMO converter is switched at permissible high frequencies based on the EMI mask. The automotive-class SIMO dc-dc converter is designed and integrated with a state-of-the-art class-D audio amplifier using 110nm BCD process technology offered by STMicroelectronics. The SIMO converter provides a battery tracking boost and a ground referred buck outputs for driving the class-D power stage. A unique feature of the converter is the generation of a floating voltage across half battery to supply the DSP core of the amplifier. The converter starts-up as boost converter alone followed entering boost-assisted SIMO converter mode. The active area occupied is 2.5mm2. The switching frequency is 2-2.4MHz. The converter has a load capability to drive up to 4 channels of a class-D power stage with peak efficiency of 86% and peak output power of 2.8W. The ripple voltage on the regulated outputs is below 25mV. The SIMO converter is able to sustain the automotive battery crank and dump conditions across the battery variation range of 4.5-27V. A line regulation of 6.3-16.2mV/V and a load regulation of 0.16mV/mA are provided by the SIMO converter. In the presence of wide range of battery variations, the SIMO converter incorporates all the necessary protections circuits and under/over voltage interrupts through I2C communication.
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PONNAMANENI, SANJITH KUMAR. "A NOVEL AUDIO AMPLILFIER COMBINING LINEAR AND SWITCHING TECHNIQUES." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1109274094.
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Svadbík, Vít. "Návrh a konstrukce spínaného audio koncového zesilovače." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2010. http://www.nusl.cz/ntk/nusl-218603.
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This work describes the design of audio amplifiers operating in switching mode. The first part describes basic principles of the power stage switching concept. There is described differences between classes of amplifiers according to technology. The second larger part includes design and construction of the switching amplifiers. Design is implemented, including the preamplifier and power supply. Power supply works in switching mode. The measured parameters of the proposed facility are given in the last part.
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Caballero, Angel A. 1981. "A class-D-tracking-rail class-A audio power amplifier." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28384.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (p. 63-64).
A tracking-rail power audio amplifier was designed and partially implemented to deliver up to 100W into an 8Q load with very low signal distortion and high power efficiency. The design uses a class-A amplifier, known for its low signal distortion but low power efficiency (less than 50%), to amplify the audio signal. Class-D amplifiers, known for their high power efficiency (greater than 85%) but high signal distortion, provide a signal output that will serve as the supply voltages of the output stage of the class-A amplifier. Thus, the rails will track the audio signal, highly increasing the power efficiency of the Class-A amplifier. This amplifier can achieve a theoretical efficiency of 80%, but, in practice, it is closer to 70%.
by Angel A. Caballero.
M.Eng.
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Williams, David J. "Songworld : for 7 amplified singers and digital audio tape." Thesis, Keele University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323713.
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Engstrand, Johan, Niklas Kavathatzopoulos, and Jonathan Nordenholm. "Simulation and Construction of a Half-Bridge Class D Audio Amplifier." Thesis, Uppsala universitet, Fasta tillståndets elektronik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-353789.
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Usage of class D audio amplifiers has become increasingly widespread in recent years, mainly due to their high efficiency, which can reach almost 100 %. Class D amplifiers can also be compact, making them suitable for mobile applications. In contrast, the most efficient conventional amplifiers such as class B can reach a maximum efficiency of 78.5 %. The high efficiency of class D amplifiers can be attributed to the switching stage, which in the case of a half-bridge design consists of two amplifying MOSFETs. These MOSFETs are never on at the same time, which minimizes the quiescent current and thereby the power losses. The goal of this project was to design, simulate and construct a half-bridge class D audio amplifier. A working amplifier with 80 % efficiency was built, with power losses occuring mainly in the voltage regulators. Simulations of the amplifier corresponded well with the constructed amplifier apart from issues originating from the aforementioned voltage regulation as well as the triangle wave generator. The goal of the project was achieved and the finished amplifier possessed good sound quality and little unwanted noise. To further improve on the design, better voltage regulation, a full-bridge configuration and a feedback loop could be utilized.
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Konečný, Jiří. "Návrh stereo audio koncového zesilovače spínané třídy." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-220270.
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This text analyzes characteristics of audio power amplifiers in class D. The emphasis is placed on more detailed analysis of modulators, drivers, connection topology of power transistors. In the next section of text are analyzed available integrated circuits of power amplifiers in class D which are manufactured by world producers. The last part describes design of all parts of amplifier in class D with discrete components and also of power supplies. According to the plans, the individual parts are made. All parts are tested by measurements and results are evaluated.
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Kemp, Pieter Stephanus. "The design of an analogue class-D audio amplifier using Z-domain methods." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20084.
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Thesis (MScEng)--Stellenbosch University, 2012ENGLISH ABSTRACT: The class-D audio power amplifier has found widespread use in both the consumer and professional audio industry for one reason: efficiency. A higher efficiency leads to a smaller and cheaper design, and in the case of mobile devices, a longer battery life. Unfortunately, the basic class-D amplifier has some serious drawbacks. These include high distortion levels, a load dependent frequency response and the potential to radiate EMI. Except for EMI, the aforementioned issues can be mitigated by the proper implementation of global negative feedback. Negative feedback also has the potential to indirectly reduce EMI, since the timing requirements of the output devices can be relaxed. This thesis discusses the design of a clocked analogue controlled pulse-width modulated class-D audio amplifier with global negative feedback. The analogue control loop is converted to the z-domain by modelling the PWM comparator as a sampling operation. A method is implemented that improves clip recovery and ensures stability during over-modulation. Loop gain is shaped to provide a high gain across the audio band, and ripple compensation is implemented to minimize the negative effect of ripple feedback. Experimental results are presented.
AFRIKAANSE OPSOMMING: Die klas-D klankversterker geniet wydverspreide gebruik in beide die verbruiker en professionele oudio industrie vir een rede: benuttingsgraad. ’n Hoër benuttingsgraad lei tot ’n kleiner en goedkoper ontwerp, en in die geval van draagbare toestelle, tot langer batterylewe. Ongelukkig het die basiese klas-D klankversterker ernstige tekortkominge, naamlik hoë distorsievlakke, ’n lasafhanklike frekwensierespons en die vermoë om EMI te genereer. Behalwe vir EMI kan hierdie kwessies deur die korrekte toepassing van globale negatiewe terugvoer aangespreek word. Negatiewe terugvoer het ook die potensiaal om EMI indirek te verminder, aangesien die tydvereistes van die skakel stadium verlaag kan word. Hierdie tesis bespreek die ontwerp van ’n geklokte analoog-beheerde pulswydte-modulerende klas-D klankversterker met globale negatiewe terugvoer. Die analoogbeheerlus word omgeskakel na die z-vlak deur die PWM vlakvergelyker as ’n monster operasie te modelleer. ’n Metode word geïmplementeer wat die stabiliteit van die lus verseker tydens oormodulasie. Die lusaanwins word gevorm om ’n hoë aanwins in die oudioband te verseker en riffelkompensasie word geïmplementeer om die negatiewe effek van terugvoerriffel teen te werk. Eksperimentele resultate word voorgelê.
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Pereira, Nuno Ruben Ferreira. "Implementation of a sigma delta modulator for a class D audio power amplifier." Master's thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/10046.
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Salvatierra, Thomas R. "Design and Evaluation of an Audio-Frequency Transresistance Amplifier for Magnetic Tape Playback." Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1301007790.
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Crafford, Crafford Hendrik Lambert Helberg Hendrik Lambert Helberg. "Design and development of a high efficiency modulated Class E amplifier." Thesis, 2006. http://hdl.handle.net/10352/270.
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M. Tech. (Chemical Engineering, Faculty of Engineering and Technology), Vaal University of TechnologyAmplitude modulation is not commonly associated with effective amplifying. This work focuses on implementing amplitude modulation into a high efficiency Class E amplifier. Different types of amplifiers are compared with each other, to show the advantages of using a Class E amplifier. The theory of the Class E amplifier is dealt with in detail. A harmonic filter is designed for the amplifier to make it radio spectrum friendly. The modulation process is implemented with the aid of a transformer into the Class E amplifier. The advantage of this is that the transformer serves both as a radio frequency choke for the Class E circuit as well as a modulator. The implementation of the amplitude modulation into the high efficient Class E circuit was successful. The final Class E circuit had superb efficiency, the harmonic filter showed good harmonic attenuation and the modulation process had low distortion. All this resulted in a fine low power AM transmitter.
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Liao, Ching-Chuan, and 廖慶全. "Low Power Class D Audio Amplifiers." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/18167353982077172633.
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碩士逢甲大學
電子工程所
94
Discrete amplifier designs based on the class-D topology are not new, but recent advances in semiconductor technology have generated a renewed interest in using the topology in integrated circuit based audio power amplifiers. The motivating factor driving research in class-D-based ICs is efficiency. Their increased efficiency provides two main advantages over class-AB amplifiers. The first advantage is the reduction of supply current required which translates to longer run-time on batteries, or reduced power supply requirements which translates to lower-cost, smaller power supply designs. The second advantage class-D audio power amplifiers offer is the reduction of heat generated which translates to more output power in a smaller package, and elimination of heat sinks. These two advantages make class-D audio power amplifiers attractive to consumer electronics. A single-chip high-efficiency 1.5V class-D audio power amplifier is presented in this paper. This class-D audio power amplifier has the efficiency of 90%. A 8ohms load is used for amplifier design. The lowest total harmonic distortion is 0.38% when 500kHz triangle wave is used. In this work, the designed circuit fabricated by TSMC 0.35 m CMOS technology is a kind of analog integrated circuit.
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TU, YEN-KUAN, and 杜彥寬. "A Study on the Audio Power Amplifiers." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/27430060178099202850.
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碩士中華大學
電機工程學系
105
Electronic audio equipment is indispensable equipment for modern human playing music. The audio power amplifier is a last stage for driving speaker. The amplifier’s good or bad will impact that your ears hearing the sound is good or bad. In this thesis, computer-aided design software is used to design, simulate and verify Class A, Class B, and Class AB amplifiers. The practical Class A amplifier is proposed by J. L. Linsley Hood in 1969. In this thesis, the amplifier’s characteristics are simulated and verified by a modern EDA tool(Cadence), which it has excellent characteristics, no cross-over distortion, and low total harmonic distortion. But it has two disadvantages, first one is the lowest efficiency and producing high heat, the second is in the small level of sound still need to consume energy of largest volume. Class B amplifier is not suitable for use in audio, because it produced cross–over distortion. But it is the most power-saving in linear power amplifiers. The thesis focuses on its efficiency through EDA tool’s simulation verification to exam its architecture. In this thesis, Class AB amplifier architectures are discussed, which they are modified form Class B amplifier with adjusted bias voltage point. First I have developed specifications, then executed theoretical design calculations, and finally perform the implementation and test. I also use EDA tool’s layout function to make print circuit board. Then all parts are assembled on the circuit board. All procedure is step by step. It’s a useful reference for beginner experiments.
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Zou, Bo-Gang, and 鄒博岡. "A Single-Inductor Bipolar-Output Converter with Reference Voltage Tracking Technique for Supplying Audio Amplifiers." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/5s54t6.
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碩士國立交通大學
電機工程學系
106
Power amplifier has been widely used in a variety of electronic products, including audio amplifier in the circuit to achieve the audio signal driver. The traditional audio amplifier has a supply voltage of 5V and 0V as ground, and the output common mode level is at 2.5V, so it needs a large output capacitor (~22uf) to filter noise. Large capacitor makes the area increase. This paper presents a single inductor bipolar output(SIBO) converter can effectively solve this problem, because the use of multiplexing technology to produce positive and negative voltage supply audio amplifier, making the audio amplifier output common mode at 0V, so it can remove the large capacitor saving area and decrease power consumption. This power management system has a reference voltage tracking function, can effectively enhance the efficiency of the audio amplifier. The converter architecture of this paper simulates the conversion of the power supply battery voltage into a set of equal positive and negative voltages and can change with reference voltage waveform. In addition, the converter of this paper achieves a maximum efficiency of 88.9% due to reduced unnecessary current losses. Keywords: audio amplifier, common mode level, single inductor bipolar-output, reference voltage tracking
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Shih-HsiungChien and 簡士雄. "Low-Quiescent-Current Low-Distortion Analog-Input and High-Dynamic-Range Digital-Input Class-D Audio Amplifiers." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/9394d3.
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Wang, Di, and 王迪. "A High Efficiency and Adjustable Frequency Modulation Single-Inductor Bipolar-Output DC-DC Converter for Supplying Audio Amplifiers." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/v39kgy.
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碩士國立交通大學
電機工程學系
106
Power amplifier has been widely used in a variety of electronic products, including audio amplifier in the circuit to achieve the audio signal driver. The traditional audio amplifier has a supply voltage of 5V (VDD) 0V (VSS), and the output common mode level is at 2.5V, so it is necessary to use a large capacitor (~22uf) to eliminate noise interference and drive the sound. The Large capacitor makes area and cost increase. This paper presents a single inductor bipolar output(SIBO) power management system can effectively solve this problem, because using of multiplexing technology could produce positive and negative voltage supply audio amplifier and make the audio amplifier common mode output voltage at 0V, so it can remove the large capacitor to save area and decrease cost. This power management system could adjust the frequency according to different load. That can effectively enhance the efficiency of the audio amplifier when it works in light load. The power management architecture of this paper uses a 0.15um process to convert the battery supply voltage into a set of equal and bipolar voltages. In addition, the power supply system of this paper achieves a maximum voltage conversion ratio of 92% and an energy conversion efficiency of 89.4% due to reduced unnecessary losses.
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Πυροβολάκης, Γεώργιος. "Σχεδίαση και σύγκριση ενισχυτών ηχητικών συχνοτήτων διαφόρων τεχνολογιών." Thesis, 2013. http://hdl.handle.net/10889/6029.
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Η παρούσα διπλωματική αποτελείται από μια σειρά από projects συστημάτων επεξεργασίας ηχητικού σήματος, με κύριο προσανατολισμό το ηχητικό σήμα της ηλεκτρικής κιθάρας. Πολλά από τα ακόλουθα projects είναι βασισμένα σε ήδη υπάρχοντα κυκλώματα που κυκλοφορούν στο εμπόριο και έχουν τροποποιηθεί έτσι ώστε να έχουν βελτιωμένη απόδοση (λιγότερος θόρυβος, μικρότερη κατανάλωση ισχύος) και να έχουν καλύτερη ηχητική απόκριση (σύμφωνα με τα δικά μας -υποκειμενικά- κριτήρια).
Τα πρώτα projects ως ενεργά στοιχεία χρησιμοποιούν είτε διακριτά τρανζίστορ και διόδους, είτε ολοκληρωμένα κυκλώματα τρανζίστορ-διόδων. Τα δύο τελευταία χρησιμοποιούν τριοδικές και πεντοδικές λυχνίες κενού. Με αυτόν τον τρόπο έχει επιτευχθεί και μια κλιμακούμενη αύξηση της δυσκολίας των projects.--
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Lee, Shun-An, and 李訓安. "A Single-Inductor Bipolar-Output DC-DC Converter Using Ferrite Beads with Adaptive Compensation Mechanism for the Supply of Audio Amplifiers in Mobile Platforms." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/p47fmy.
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碩士國立交通大學
電控工程研究所
106
Nowadays, multimedia, including audio and visual products has become increasingly popular. Due to the increase of environmental awareness and protection, design a better electronics with power-saving, smaller size and good audio quality for consumer is a potential trend these years. Thus, in order to achieve a high-efficient and compact integrated audio module through the combination of single-inductor bipolar-output switching DC-DC converter and audio amplifier circuit, the combination of audio amplifier and power management unit can provide audio amplifier with optimal supply voltage and ensure its output voltage swing and linearity. Moreover, the purpose of using the priority of the energy distribution path is to reduce the switch switching loss while making the gate driving voltages of the power switches change is to enhance the power conversion efficiency in power management module. In order to make sure that the system is stable in wide variation of switching frequency, such as 768kHz, 1.536MHz, 1.6MHz and 3.072MHz, and avoid the sub-harmonic oscillation from happening. Hence, it is implemented an adaptive system compensation and slope compensation mechanism. Finally, this SIBO DC-DC converter is implemented by U153 with 10V-LDMOS process and the simulation results is shown in section 4.7.1.
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Du, Yi-Cheng, and 杜易澄. "A BJT Audio Power Amplifier." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/7x79v3.
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碩士逢甲大學
電機工程所
90
This thesis presents a design of bipolar audio power amplifier. The amplifier proposed in this thesis is designed for headphone. It must gain 35 mW on the load of 32 ohm and the power dissipation needs to be less than 500 mW. The designed amplifier is fabricated by AMS 0.8 , double-metal, double-poly, N-well BiCMOS process. The characteristic of the amplifier lies in Class-A output stage and matches up with a bias control circuit. This bias loop makes hard drive transistor still to pass through constant current. When transmitting a signal, the two output transistors can flow without obstruction and acquire needed output signal. The audio power amplifier connects with a low-level signal processing circuits and the real world, so it must have lower distortion and better stability (PM＞60 degree). Nowadays the application of integrated circuit lies more and more emphasis on power consumption. As a result, the power amplifier in this thesis also needs to meet this requirement, and the power dissipation should be less than 500 mW. The input impedance of audio IC generally requires up to 30 k . In this thesis, we use Darlington configuration to improve input impedance. Since Darlington configuration always result in high input impedance, so we also connect constant impedance in the input to fulfill the required specification.
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Lin, Kai-Hsiang, and 林凱祥. "Design and Implementation of Audio Amplifier." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/19219038225567758975.
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碩士國立交通大學
電機與控制工程系所
95
A method to design an audio circuit is presented,and a voice chip with record/play is an example. The standard is set and the design proceeds with it. To realize a useful audio circuit,the emphasis is put on the methods and flow to design it.The performance indicators are also evaluated. At first,the design method and flow to design the preamplifier , the filter circuit and the power amplifier are mentioned. Besides,the audio signal input and the output speaker are introduced.There are examples to explain how to design an complete audio amplifier system and it is simulated by circuit simulation software ,PSpice. The realized circuit is measured with oscilloscope Tektronix TDS2002 and mathematic software Matlab 7.0. The results of simulation and measure about the frequency response,frequency spectrum analysis,total harmonic distortion,signal/noise ratio and efficiency,are compared. Finally,the circuit is realized.
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Liao, Tze Ru. "Delta Sigma Modulated Class D Audio Amplifier." 2006. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-1907200611045200.
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Ming-Jhe, Du. "CMOS Highly-Efficient Class-D Audio Amplifier." 2006. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-2507200601495000.
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HWA-YUAN, LIU, and 劉華元. "Digital Input Class-D Audio Amplifier Design." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/04894591351221180693.
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碩士中華技術學院
電子工程研究所碩士班
96
Abstract Due to power saving is current trend for portable electronic product and it is very import to design a system. Although audio amplifier design and application focus quality before,but people are leading concern for efficiency to use consumer product now. First, this master thesis introduce traditional audio amplifier structure and characteristic of Class A,B,AB, moreover, we compare with digital input audio amplifier Class D.we also detail various characteristics and advantage of Class D in the preceding chapter. The major content is discussed how to design a digital input modulator of Class D. We design this digital structure include gain control、3 stage filter、5 order 6 bits sigma-delta modulator and PWM. Per our analysis form actual measurement we have to observe if we achieve original opinion, or not? Maybe we can obtain a way to improve the defects further.
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Tsai, Chun-Hao, and 蔡俊豪. "Design of Filterless Class D Audio Amplifier." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/22201137769579819716.
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碩士國立臺灣大學
電機工程學研究所
95
Over the years, the commercial audio amplifiers are dominated by Class AB amplifier. However, most of Class AB amplifier power efficiency is below 70%, which reduces the overall system battery lifetime and increases the heat dissipation. Therefore, the Class D amplifier with the advantages of high efficiency has been widely investigated recently comparing to the Class AB amplifier. A Class-D amplifier with conventional PWM modulation requires an output filter which needs large area and increasing cost. Therefore, we use unipolar switching pulse width modulation scheme to realize a filterless Class-D power amplifier. In this thesis, we focus on the implementation of Class D amplifier on a monolithic integrated circuit. We observed that the total harmonic distortion (THD) increases due to non-linearity in the triangular wave. To overcome this problem, negative feedback is applied to reduce the harmonic distortion. The circuit is designed using TSMC (2P4M) 0.35um 3.3V CMOS process. The entire circuit contains an error amplifier, two hysteresis comparators, a triangular wave generator, gate-driver circuits, and the H-bridge. The details of the entire circuit will be described thoroughly in this thesis. When a 0.4V, 1KHz input sine wave is applied, the maximum THD is 0.13% and the efficiency is 88.5%.
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Ru, Liao Tze, and 廖澤儒. "Delta Sigma Modulated Class D Audio Amplifier." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/15258309802344855509.
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碩士國立臺灣大學
電子工程學研究所
94
In the portable devices such as PDA, MP3 player or mobile phone and mobile amusement system, the battery life is a very important issue. In order to strengthen the battery lifetime, the high power efficiency will be better. The efficiency of power amplifier is very important. The traditional class A or class AB have lower efficiency than class D. The efficiency of class D will achieve 100% theoretically. The class D audio amplifier is usually with PWM modulator or delta sigma modulator to transform the input signal to a series of pulse signal to control the class D circuit. The traditional PWM modulator or delta sigma modulator are all with clock circuit inside. In order to reduce the clock circuit, a delta sigma modulator with hysteresis comparator is presented in this thesis. In this topology, we can save the chip area and also can achieve a good performance in THD and efficiency. The THD is 0.9% and the efficiency is 87% with 10K Hz input signal in this thesis.
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Du, Ming-Jhe, and 杜明哲. "CMOS Highly-Efficient Class-D Audio Amplifier." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/06790414067614930660.
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碩士國立臺灣大學
電子工程學研究所
94
A one-chip integrated circuit of a 2-W class-D audio power amplifier with very high efficiency using a CMOS technology is presented. Compared with traditional class-AB amplifiers that are very poor at efficiency, most below 50%, the proposed class-D amplifier has the efficiency of 90% at the smaller distortion level. The class-D amplifiers generate pulse-width-modulated (PWM) signals by comparing a triangle-wave with input-signals. An output stage with zero dead time and high efficiency is applied to improve the linearity and reduce wasted battery energy. An approach to reducing distortion is applied by using feedback calibration.
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SHIH-HSIANG, LIN, and 林世祥. "High Efficiency Class-D Audio Amplifier Design." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/17599257173454224387.
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碩士聖約翰科技大學
電子工程系碩士班
97
For the fast growing of electric products, the consumer electronic products are designed toward the direction of tiny and portable. Audio amplifiers are mass needed in these products. The major demands of the consumer products, for example, are: power dissipation, product volume, and heat radiation. The most important design parameter of these is power efficiency. Increasing the power efficiency, it not only lasts the Class-D amplifier battery lives, but also operates in an extra low operating temperature. This paper designs Class-D amplifies based on self-tuning master-slave architecture and sliding mode control architecture. They are implemented with TSMC 0.35um 2P4M CMOS process. By using double triangle-wave generators and double feedback circuits in self-tuning mater-slave architecture, the efficiency of Class-D amplifier is increased and the total harmonic distortion (THD) is decreased. The chip size is 1.575mm x 1.575mm. The measure results show that when the input voltage is 0.6V, the power dissipation is 204mW, and the power efficiency is 89%. Second, the sliding mode control Class-D amplifier is using the sliding mode control modulation and bridge-configured architecture. The chip size is 1.575mm x 1.575mm. The simulation results show that when the input voltage is 0.6V, the power dissipation is 2.13W, and the power efficiency is 90.2%.
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Wen, Tsai-sheng, and 溫在勝. "A FILTERLESS DIGITAL CLASS-D AUDIO AMPLIFIER." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/77717355543363797232.
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碩士大同大學
電機工程學系(所)
105
Class-D amplifiers become more and more important on the personal mobile system, because of their high efficiency. A conventional class-D amplifier needs a low-pass filter between the output stage and the speaker, but these filters which need to endure high output power usually quite bulky. This design uses filterless technology to eliminate the problem and reduce the circuit area. These days, many companies use USB interface to replace the traditional audio jack. Filterless class-D amplifiers output the digital signal directly, and thus have the potential on these kinds of applications. This thesis will review analog UPWM, digital PWM, digital PDM, and mixed-signal architectures, and make comparison. A chip using digital PDM architecture has been implemented with TSMC 0.18μm CMOS process and the standard cell library provided by TSMC. There is a 16-bit input data bus on this chip. The simulated THD of this chip could achieve 0.000059%. The chip area of the circuit is about 1.27 .
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LI, CHIA-HENG, and 李家恒. "Design of Vacuum Tubes Audio Power Amplifier." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/55797248717703612869.
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碩士建國科技大學
電機工程系暨研究所
102
This paper is designed to achieve a balanced Vacuum tubes audio amplifier design application, along with advances in semiconductor technology, household appliances audio products with the power amplifier circuit is relatively widely used by the market, the audio power amplifier power is an important component of integrated circuits, has widely used in electronic consumer products, and in order to be able to enjoy high-quality sound, but also the use of Vacuum tubes audio amplifiers balanced sound choice as a home appliance, so there is a demand Vacuum tubes sound design and significance of the actual market, the paper Vacuum tubes sound design a class B dual-channel output power of 30 W, and a large audio amplifier with mute standby function, the result can be achieved in actual verification electrical performance and stability of the entire system circuit good total harmonic distortion, and high reliability .
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LIN, YOU-DA, and 林佑達. "An Audio-Hole-Free Over-Temperature Protection Technique for Class-D Audio Amplifier." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/r824g8.
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碩士國立雲林科技大學
電子工程系
104
Class-D audio amplifiers have been widely used in a variety of audio equipment. It is characterized by high efficiency and small size that is not able to achieve on other types of amplifiers；However, overheating problems will occur when a circuit has been processed signal at high speed and provided high power in a long time. The focus on this thesis was applying varactor to a triangular wave generator in a class D audio amplifier. Due to the effects of temperature, the current temperature sensor must adjust the value of varactor, and then control the signal’s sampling frequency. Finally, the cooling effect of protection is achieved by reducing power consumption. Furthermore, The author can obtain a current-frequency linear curve relationship by using a window comparactor which locks the varactor’s operating voltage in the range. The varactor, which was operated in Inversion-mode(I-MOS), made individual varactor’s operating region shifting by increasing the varactor’s voltage between the gate and the source. And then the varactor was connected in parallel to increase the overall voltage’s adjustable range. The required varactor’s value of the circuit was combined by the difference between the each varactor’s voltages.Finally, we can reach temperature protection effect because operating frequency is greatly reduced to make power consumption be reduced effectively.
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SU, PO-KAI, and 蘇柏愷. "Electromagnetic interference analysis for Class-D Audio Amplifier." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/6r76wx.
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碩士國立雲林科技大學
電子工程系
105
Electromagnetic Interference may be generated by operating of Electrical equipment and electronic product, so as to interfere in operation of other equipment, and even affecting human health. Switching frequency of each transistor must work rapidly in order to obtain better performance of Class D audio amplifier. This is the main source of Electromagnetic Interference. This thesis proposes that used frequency-hopping triangular wave as a carrier of Class D audio amplifier. It causes high power of harmonic no longer concentrated on switching frequency, and spreading the power into a narrow frequency range. This method can obviously reduce Electromagnetic Interference of output signal. Frequency Hopping triangular wave consists of Linear Feedback Shift Register、 Window Comparator, and the setting current circuit in this thesis. Linear Feedback Shift Register consisted of D flip flops and XOR gate. It generates numbers of pseudo random codes when triggered, and these codes separately control the transistors that cause different current to charge or discharge the capacitor of the setting circuit, so we can obtain a triangular wave with difference frequency; Window Comparator fixes the voltage on the range of and of capacitor. This circuit is fabricated by TSMC 3.3V-0.18μm process, load of the buzzer is 8ohm. According to experiment results, the total-harmonic distortion (THD) is about 53dB、 the signal-to-noise ratio (SNR) is about 74dB and the reduction of EMI is about 13dB of the thesis.