Academic literature on the topic 'Notch filter (NF)'

Abstract A new notch filter (NF) circuit based on a single differential difference operational amplifier (DDA) has been developed and studied, which is characterized by reduced current consumption in the static mode. Equations are obtained for the transfer functions and parameters of the NF, which includes a low-pass filter and a Sallen-Key high-pass filter, the signals of which are summed by the DDA. Computer modeling of the NF in CAD Micro-Cap was performed.

This paper describes the design of a self-tuning OTA-C notch filter (NF), based on a phase control loop concept. The phases of filter input and output signals are compared and the phase error is used to generate the control voltage, which adjusts the transconductances of operational transconductance amplifiers (OTAs) and, consequently, tunes the NF center frequency without quality factor variation. The proposed solution is robust to filter parameter variations. The filter is implemented in 0.13[Formula: see text][Formula: see text]m SiGe BiCMOS technology. Under the typical circuit operating conditions, the center frequency tuning is within the range from 70[Formula: see text]MHz up to 150[Formula: see text]MHz, with tuning error less than 1%. The power consumption is less than 3.6[Formula: see text]mW, the 1[Formula: see text]dB gain compression point is [Formula: see text]2.5[Formula: see text]dBm, the input (IIP3) and output (OIP3) intercept points are 3.47 and 9.07[Formula: see text]dBm, respectively, and the total filter effective noise voltage is 4.35[Formula: see text][Formula: see text]Vrms. The filter structure is suitable for complementary metal-oxide-semiconductor (CMOS) implementation.

The removal filter coefficients in this technique are dependent on the jammer’s power and its Instantaneous Frequency (IF) information, which can both be obtained in the time–frequency domain (adaptive filtering techniques). The dependence of the removing/reducing filter characteristics on the interference power is critical, as it allows an optimal trade-off between removal interference and the amount of self-noise generated by the filter. This trade-off is bounded by the two extreme cases of no notch filter (no self-noise) and full suppression (k1 = 1) for both low- and high-power jammer values. In this paper, a cascade second-order adaptive direct Infinite Impulse Response (IIR) Notch Filter (NF) with a gradient-based algorithm to suppress the Continuous-Wave (CW and MCW) interference is proposed for maximizing the receiver Signal-to-Noise Ratio (SNR) in a Quadrature Phase-Shift Keying (QPSK)-modulated signal. The suppression approach consists of two Adaptive IIR NFs (ANFs) based on a direct-form structure: the Hd1(z) and Hd1(z). The proposal in this work presents a low-complexity Time-Domain (TD) algorithm for controlling the update filter coefficient and notch depth. Simulation results demonstrate that the proposed approach represents an effective method for removing/reducing the impacts of CWI/MCWI, resulting in improved system performance for low- and high-power jammer values when compared with the case of full suppression (k1 = 1); furthermore, it also improves the notch filter’s output SNR for a given Jamming-to-Signal Ratio (JSR) value and Bit Error Ratio (BER) performance. For example, the SNR output of the proposed IIR NF was enhanced by 7 dB versus the case without a filter when Eb/No = 15 dB and JSR = −5 dB. The proposed method can detect and mitigate weak and strong jamming with JSR values ranging from −30 to 40 dB, and can track the hopping frequency interference. Moreover, an improved BER performance is seen as compared to the case without an IIR NF.

In this research paper, a voltage mode second order universal filter using Four Terminal Floating Nullor (FTFN) is presented. The proposed design uses Three Input Single Output (TISO) for the realization of all filter responses namely Low Pass Filter (LPF), High Pass Filter (HPF), Band Pass Filter (BPF), Notch Filter (NF) and All Pass Filter (APF) by using proper input selection. The analog building block, FTFN is simply realized with two commercially available AD844 ICs. The proposed second order universal filter comes with a single FTFN block with four passive components in which no component matching is required for filter realization. The universal filter is well verified using PSPICE simulation. In addition, experimental verification for the second order APF has been performed that confirms the theoretical expectations.

The configuration with electronic tunable characteristics that can work in mixed mode may be useful from IC realization viewpoint and application adaptability. This paper proposes an electronically tunable mixed mode universal filter based on multiple output current controlled current conveyor (MOCCCII) and this single topology without any alteration can be used in all four modes i.e., voltage (VM), current (CM), transimpedance (TIM) and transadmittance (TAM). The architecture uses four MOCCCIIs and two grounded capacitors; and can realize universal filter functions — low pass (LP), band pass (BP), high pass (HP), notch (NF) and all pass (AP) for all four modes. Moreover the input impedance is high and output impedance is low for voltage signal and vice-versa for current signal, hence the proposed topology is suitable for cascading for all four modes. The workability of the proposed circuit has been verified via SPICE simulations using AMS 0.35 μm CMOS technology.

This paper proposes a compact, high-linearity, and reconfigurable continuous-time filter with a wide frequency-tuning capability for biopotential conditioning. It uses an active filter topology and a new operational-transconductance-amplifier (OTA)-based current-steering (CS) integrator. Consequently, a large time constant τ , good linearity, and linear bandwidth tuning could be achieved in the presented filter with a small silicon area. The proposed filter has a reconfigurable structure that can be operated as a low-pass filter (LPF) or a notch filter (NF) for different purposes. Based on the novel topology, the filter can be readily implemented monolithically and a prototype circuit was fabricated in the 0.18 μm standard complementary-metal–oxide–semiconductor (CMOS) process. It occupied a small area of 0.068 mm2 and consumed 25 μW from a 1.8 V supply. Measurement results show that the cutoff frequency of the LPF could be linearly tuned from 0.05 Hz to 300 Hz and the total-harmonic-distortion (THD) was less than −76 dB for a 2 Hz, 200 mVpp sine input. The input-referred noises were 5.5 μVrms and 6.4 μVrms for the LPF and NF, respectively. A comparison with conventional designs reveals that the proposed design achieved the lowest harmonic distortion and smallest on-chip capacitor. Moreover, its ultra-low cutoff frequency and relatively linear frequency tuning capability make it an attractive solution as an analog front-end for biopotential acquisitions.

The paper presents a new second-order single input multiple output (SIMO) type current mode (CM) universal filter. The proposed circuit uses two dual-X second generation multi-output current conveyors (DX-MOCCII), two grounded capacitors and three grounded resistors. The circuit configuration realizes low-pass filter (LPF), high-pass filter (HPF), band-pass filter (BPF), notch filter (NF) and all-pass filter (APF) responses simultaneously at different output terminals. The new circuit enjoys the features of low input impedance and high output impedance, which is desirable and useful for cascadability in CM circuits. For realizing the universal filter responses, the proposed circuit configuration does not require matching constraint of passive components and both active and passive sensitivities are found low. In addition, the extension of the proposed circuit as a resistorless universal filter has also been presented. As an application of the proposed filter, inverting band pass output is connected to a negative unity gain current follower in a close loop to design voltage and CM multiphase sinusoidal oscillators (MSOs). Comparison of the proposed configuration with available literature is given. The PSPICE simulation of the filter and its application as MSO are performed to verify the agreement with the theoretical proposition.

Introduction: The programmed cell death 1 (PD-1) monoclonal antibodies (MoAbs) nivolumab and pembrolizumab induce response rates exceeding 70% in relapsed/refractory (R/R) classical Hodgkin lymphoma (cHL). The lack of response to PD-1 MoAbs, and the relapse occurring in most patients who had responded to PD-1 blockade suggest that tools to identify the determinants of response/resistance to PD-1 MoAbs are urgently required. We hypothesized that the characterization of the mutational profile of circulating tumor DNA (ctDNA) could represent a valuable tool to track clonal evolution-driven resistance to checkpoint inhibitors. Patients and Methods: 21 R/R cHL (median age, 32 years; range, 19-51) who had received a median of 5 (range, 3-7) chemotherapy lines, including autologous stem cell transplantation (77%) and brentuximab vedotin (100%), were treated with PD-1 MoAbs. Blood samples were profiled by CAPP-Seq strategy. We analyzed ctDNA and paired DNA from peripheral blood mononuclear cells (PBMCs), as source of germline DNA to filter out polymorphism and sequencing errors. A targeted resequencing panel optimized to include the coding exons and splice sites of 133 genes (320 Kb) that are recurrently mutated in B-cell lymphomas was used. Libraries were prepared from ctDNA and germline gDNA according to the CAPP-seq targeted enrichment strategy (Nimblegen-Roche) and subjected to ultra-deep-next generation sequencing (NGS) using the Nextseq 500 platform (Illumina). The sequencing was performed to obtain a depth of coverage >2000x in >80% of the target region in all samples, which allowed a sensitivity of 3x10-3. A stringent and completely automated bioinformatic pipeline was applied to call non-synonymous somatic mutations, using the somatic function of VarScan2. Results: After a median of 26 (range, 9-63) cycles of PD-1 inhibitors best response was complete remission (CR) for 9 patients (42%), partial remission (PR) for 6 (29%) and progressive disease (PD) for 6 (29%). Patients achieving PR experienced a disease control lasting for 4.5 to 24 months and subsequently underwent PD. Plasma and PBMC samples were collected at baseline, every five cycles of therapy, and end-of-therapy (EOT). At baseline, 18 of 21 patients could be successfully genotyped, whereas three were not. Evaluable patients showed a mean (±SD) number of mutated genes and mutations per patient of 7.3±5.1 (range, 2-22) and 9.9±8.4 (range, 2-37), respectively. Genes recurrently affected by non-synonymous somatic mutations in >20% of R/R cHL included STAT6 (45%), SOCS1 (40%), ITPKB (35%), GNA13 (35%), TP53 (20%), TNFAIP3 (15%). At baseline, no association of distinct DNA mutations with resistance to PD-1 inhibitors could be demonstrated. Signaling pathways targeted by DNA mutations included JAK-STAT, NF-κB, PI3K-AKT, cytokine, NOTCH, immune evasion. The concentration of ctDNA reported as haploid genome equivalent per ml (hGE/ml) was 592.2 (range, 2-2,746), with values of hGE/ml detected in PD patients being significantly higher as compared to CR patients (P=.0437). As compared to cycle 0, the hGE/ml of ctDNA at cycle 5 showed a significant reduction (592.2 vs. 67, P<.0008) which was followed by further hGE/ml decline in CR patients (to 14 P=.05) and further hGE/ml increase in PD patients (to 1,300 P=.1). At cycle 5, all CR/PR patients showed complete disappearance of baseline mutations, which were replaced by completely novel clones. In all CR/PR patients, this pattern of "clonal reshaping" was repeatedly detected over time. In striking contrast, at cycle 5, PD patients showed the persistence of baseline mutations. In all PD patients, this pattern of "clonal persistence", was repeatedly detected over time. In 4 patients, resistance to PD-1 inhibitors was associated with the appearance of a TP53 mutated clone. Although, a formal correlation of circulating DNA mutations with standard FDG-PET imaging was outside the objective of this study, both the "clonal reshaping" and "clonal persistence" patterns could be demonstrated to correlate with the results of FDG-PET. Conclusions: Analysis of ctDNA allows detecting tumor-specific mutations in R/R cHL. The longitudinal tracking of circulating DNA mutations in these patients identifies two different patterns of clonal evolution associated with sensitivity (clonal reshaping) or resistance (clonal persistence) to checkpoint blockade. Disclosures Santoro: Eisai: Consultancy, Speakers Bureau; Novartis: Speakers Bureau; Lilly: Speakers Bureau; Sandoz: Speakers Bureau; Pfizer: Consultancy, Speakers Bureau; Arqule: Consultancy, Speakers Bureau; Gilead: Consultancy, Speakers Bureau; AstraZeneca: Speakers Bureau; Celgene: Speakers Bureau; Servier: Consultancy, Speakers Bureau; Takeda: Speakers Bureau; BMS: Speakers Bureau; Roche: Speakers Bureau; Abb-Vie: Speakers Bureau; Amgen: Speakers Bureau; BMS: Consultancy; Bayer: Consultancy, Speakers Bureau; MSD: Speakers Bureau. Rossi:Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Honoraria, Other: Scientific advisory board; Janseen: Honoraria, Other: Scientific advisory board; Roche: Honoraria, Other: Scientific advisory board; Astra Zeneca: Honoraria, Other: Scientific advisory board. Carlo-Stella:ADC Therapeutics: Consultancy, Other: Travel, accommodations, Research Funding; Sanofi: Consultancy, Research Funding; Celgene: Research Funding; Janssen Oncology: Honoraria; MSD: Honoraria; Servier: Consultancy, Honoraria, Other: Travel, accommodations; Amgen: Honoraria; Boehringer Ingelheim: Consultancy; Novartis: Consultancy, Research Funding; F. Hoffmann-La Roche Ltd: Honoraria, Other: Travel, accommodations, Research Funding; BMS: Honoraria; Janssen: Other: Travel, accommodations; Takeda: Other: Travel, accommodations; Rhizen Pharmaceuticals: Research Funding; AstraZeneca: Honoraria; Genenta Science srl: Consultancy.

The low level of received signals power makes Global Navigation Satellite Systems (GNSS) receivers vulnerable to many classes of disturbing signals. Among them, narrow band interference (NBI) might cause serious receiver performance degradation. Cancellation of NBI can be implemented by using notch filters (NF), which are controlled by two parameters: the notch frequency, which specifies the band center, and the notch bandwidth, which defines the spectrum area to be removed. The literature on the topic focuses on adapting the notch frequency, without estimating the filter bandwidth. This paper proposes a method able to determine both the notch parameters, optimizing the interference suppression. The performance analysis shows a good improvement by using the adaptive bandwidth notch filter.