Feedback Amplifier Research Articles

A 0.075 mm2 BJT-based temperature sensor with a one-point trimmed 3[formula omitted] inaccuracy of ±0.97 °C from −40 °C to 120 °C

This paper presents a bipolar junction transistor (BJT)-based CMOS temperature sensor for high accuracy, small-scale area, and low power consumption. A structure with a feedback amplifier biasing NPN transistors, combined with dynamic element matching (DEM), is proposed to avoid the effects of errors arising from the limited current gain of substrate PNP transistors in deep-submicron processes. Moreover, the switched capacitor (SC) integrators employ two single-stage cascode amplifiers for alternating cyclic sampling and integration, effectively simplifying the circuit design and reducing the operating voltage. The proposed sensor is fabricated with a standard 180 nm CMOS process, occupying an active chip area of 0.075 mm2. It consumes 39.1 μW of power at room temperature, operating with a supply voltage of 1.8 V. The measurements indicate that the sensor exhibits an inaccuracy of ±0.97 °C (3σ) across the temperature range from −40 °C to 120 °C following a single-point temperature calibration.

A Review of Current Differencing Buffered Amplifiers: Performance Metrics and Technological Advances

Current Differencing Buffered Amplifiers (CDBAs) are a critical class of analog circuit components capable of handling both current and voltage signals with minimal power consumption. Due to their low impedance voltage output, they play a significant role in modern electronics for developing high-performance, high-precision analog and mixed-signal circuits. But, designing and characterizing CDBAs pose several challenges, such as ensuring stability at high frequencies, minimizing noise impact for high-precision applications, and enhancing adaptability. Integrating CDBAs with other analog components to create multifunctional integrated circuits opens many opportunities in the analog signal-processing domain. This paper reviews the evolution and applications of CDBAs in analog signal processing. Various implementation schemes, including those using commercial Current Feedback Amplifiers (CFAs) and novel CMOS configurations, are analyzed for their performance metrics such as supply voltage, power dissipation, input/output impedances, and technology node. Future trends and challenges in advancing CDBA technology towards higher integration and lower-voltage operation are discussed, highlighting potential applications in next-generation electronics.

High-speed and high-precision measurement of biaxial in-plane displacements: tens of nanometers principle error suppression in microprobe sensors

When the microprobe sensor is faced with the demand of high-speed biaxial displacement measurement, due to the characteristics of phase generated carrier (PGC) technology, accompanying optical intensity modulation (AOIM) and unfavorable phase modulation depth (PMD) will bring about the tens of nanometer cyclic nonlinear errors, further hindering high-speed and high-precision measurement. Herein, a light source intensity stabilization system based on semiconductor optical amplifier (SOA) feedback control is achieved to eliminate the error caused by AOIM in the presence of high-frequency and large-amplitude laser modulation. Based on this, the reasons for large nonlinear errors in biaxial measurements and the inability to ensure the stability of the accuracy of multiple measurement axes are methodically examined, and an effective nonlinear error elimination methodology based on the normalized amplitude correction of active temperature scanning is proposed. The continuity and linearity of the temperature scanning are also discussed. The performed experiments show that the above approach is capable of reducing the displacement demodulation error from the nanometer scale to the sub-nanometer scale. Further, the nonlinear error is reduced to within 0.1 nm for both measurement axes and the performance becomes consistent. The dual-axis measurement resolution of the microprobe sensor reaches 0.4 nm and the measurement speed is better than 1.2 m/s with the standard deviation of lower than 0.5 nm.

Utilizing signal flow graph on multiple feedback amplifiers of NMC and DACFC with emphasis on design space exploration and conversion

SummaryOver a long time, different methods of frequency compensation of multistage amplifiers have been exploited for improvement in the behavior of stabilizing. In the present paper, the step‐by‐step conversion process of the dual active capacitive feedback compensation (DACFC) three‐stage amplifier into the nested Miller compensation (NMC) three‐stage amplifier is presented by a systematic approach and signal flow graphs (SFGs) based on the graph theory rules in graph domain. Also, according to graph rules, the conversion of the multiple feedback amplifier NMC into the multiple feedback amplifier DACFC is investigated in detail in the graph domain. During the conversion process, the difference in the gain‐bandwidth product (GBW) in the two mentioned case study's amplifiers is examined in terms of the graph at the system level. The elimination of two branches in one step of the conversion process of the SFG of the NMC into the SFG of the DACFC leads to a significant improvement in the behavior of GBW. This paper also conducts verification of the design of conventional NMC and DACFC amplifier circuits in HSPICE using 0.35‐μm CMOS technology and compares the circuit simulation results to SFG simulation results. In order to show the correctness of the idea, they are redesigned in HSPICE using 0.18‐μm CMOS technology, and appropriate results are obtained.

Use of Auditory Feedback Amplifier in Women Without Voice Complaints: A Comparison of Acoustic Measures, Self-Rated Vocal Effort, and Voice Intensity

To compare the immediate effects of using MindVox in women without voice complaints for 1, 3, 5, and 7 minutes of reading tasks, on acoustic measurements of the vocal signal in low, medium, and strongintensity emissions; on self-rated effort vocal, and on the intensity of voice reception and production. Participants read one text using MindVox for 1, 3, 5, and 7minutes. After each time, measures of self-rated vocal effort were collected (BORG CR10-BR Scale), as well as samples of the vowel /e/ at low (>70dB), moderate (≥70dB and ≤80dB), and high intensities (>80dB). Acoustic measurements (F0, short-term acoustic measurements, and cepstral peak prominence measurements) were also collected before and after the procedure and subsequently analyzed in the CTS 5.0 Vox-Metria Program. Voice reception and production intensities were captured during the reading task using two decibel meters. One decibel meter was installed near the ear (average intensity received by the ear (EAVG)) and the other near the lips (average intensity captured near the lips (LAVG)), and the data were submitted for analysis. The Cepstral Peak Prominence-Smoothed increased in the first minute, the Cepstral Peak Prominence increased in the third minute, and the jitter decreased from the first minute. All these changes were observed at low intensity and were maintained at the other time points. For every 5dB of amplification (EAVG), there was a 1dB decrease in voice production (LAVG). Using MindVox in women without voice complaints brings positive immediate effects in cepstral measures and jitter at low intensity. There is a connection between the intensity of the voice received by the ear and the intensity of voice production.

Explosive Growth of Image Sensors in Smart Government Technology and Economic Scale

CMOS image sensor is a rapidly developing image sensor product in the past decade. Relying on the advantages of process compatibility with standard CMOS process, CMOS image sensor integrates analog photoelectric photosensitive circuit and digital signal processing circuit to become a small and powerful system on chip. This article mainly studies the explosive growth of image sensors in smart government technology and economic scale. The main purpose of this article is to study the technical application of image sensors, reduce the administrative cost of social governance, improve the level of government governance, benefit the public, and realize the requirements of smart government affairs and rapid economic development of the city. This study tested the static performance of the analog-to-digital conversion circuit by inputting a limited number of sampling points, and its integral nonlinearity and differential nonlinearity were both less than 1LSB. The bandgap reference circuit provides a reference level for the entire system. It uses two PNP-type bipolar transistors parasitic in the CMOS process to achieve a temperature and voltage-independent bandgap reference voltage through the feedback of the operational amplifier. It is ideal for use In the case of resistance simulation, its accuracy reaches 16.6ppm. The scanning method of the pixel array uses multi-sampling technology to increase the dynamic range of the sensor by 2N times. The correlated sub-sampling technology eliminates the fixed pattern noise between pixel units. The use of pipelined analog-to-digital converters can achieve good resolution, speed and area compromise.Through the realization and simulation of transistor-level circuits, the performance of each part of the system meets the requirements of design and application.

Design and Analysis of a New Three-Stage Feedback Amplifier Utilizing Signal Flow Graph Domain Inspection Approach

Design and Analysis of a New Three-Stage Feedback Amplifier Utilizing Signal Flow Graph Domain Inspection Approach

Research on the stability of negative feedback circuit

The negative feedback amplifier circuit generally plays a role in stabilizing the signal and improving its accuracy, and is widely used in production and life. Therefore, it is extremely important to discuss its stability. This paper analyzes the advantages and disadvantages of different methods for judging stability through literature analysis, case analysis and comparative analysis, and gives two solutions to improve the circuit stability in combination with the circuit oscillation problem that may occur in actual operation This paper draws a conclusion that the oscillation can be reduced from two aspects: changing the additional phase shift after compensating the capacitance hysteresis or reducing the feedback depth.

A low-power low-noise amplifier with high CMRR for wearable healthcare applications

Low-noise and low-power operation are important parameters of amplifier intended for wearable healthcare applications. However, along with these parameters the amplifier must be able to deliver high Common Mode Rejection Ratio (CMRR) for mitigating the effect of 50/60 Hz interference. This paper reports capacitively coupled-capacitive feedback amplifier based on Self Cascode Current Mirror-II (SCCM-II) Operational Transconductance Amplifier (OTA). The obtained results for proposed SCCM-II OTA based amplifier shows gain of 39.79 dB, input referred noise of 2.64 μVrms, bandwidth of 0.794-343.4 Hz, area consumption of 0.154 μm2, power consumption of 2.54 μW with ±0.9 V supply. The noise efficiency factor and CMRR values for proposed amplifier are 3.87 and 122.1 dB, respectively. In-depth theoretical interpretations and mathematical modeling of amplifier are validated in 0.18μm standard CMOS process using BSIM3V3 MOS device models. The Gaussian distribution plots of proposed amplifier for 200 Monte-Carlo iterations infer mean values for gain and CMRR are 39.79 dB and 112.96 dB which are very close to their nominal values. The proposed amplifier has been compared with conventional approach as well as with literature and improvement in results is observed in terms of input referred noise, power and CMMR. These advantages of the proposed amplifier make it suitable for non-invasive wearable healthcare applications.

Realization of chaotic oscillator and use in secure communication

This scientific study reports on the practical as well as modelling of active hybrid inductor based chaotic oscillators using Current Feedback Amplifier (CFOA) and Op-Amp. Furthermore, a workable design strategy for the chaotic oscillator and its application to secure communication are provided. Here, the transient analysis of chaos waveforms is verified by using MATLAB, Multi-SIM, and LT-Spice tools. The numerical outcomes based on LT-Spice and MATLAB are closely matched. Additionally, results from the multi-SIM platform show how a secure communication network was implemented utilising the master-slave technique of synchronisation. Finally, a comparison analysis is conducted to demonstrate the originality of the suggested work.

A 4.5 μW Miniaturized 3-Channel Wireless Intra-Cardiac Acquisition System.

This article presents a chip designed for wireless intra-cardiac monitoring systems. The design consists of a three-channel analog front-end, a pulse-width modulator featuring output-frequency offset and temperature calibration, and inductive data telemetry. By employing a resistance boosting technique in the instrumentation amplifier feedback, the pseudo-resistor exhibits lower non-linearity, leading to a total harmonic distortion of below 0.1%. Furthermore, the boosting technique enhances the feedback resistance, leading to a reduction in the size of the feedback capacitor and, consequently, the overall size. To make the modulator's output frequency resilient to temperature and process changes, coarse and fine-tuning algorithms are used. The front-end channel is capable of extracting the intra-cardiac signal with an effective number of bits of 8.9, while exhibiting an input-referred noise of less than 2.7 μVrms, and consuming 200 nW per channel. The front-end output is encoded by an ASK-PWM modulator, which drives an on-chip transmitter at 13.56 MHz. The proposed System-on-Chip (SoC) is fabricated in a 0.18 μm standard CMOS technology and consumes 4.5 μW while occupying 1.125 mm2.

Faraday detector uranium isotope ratio measurement: Insights from solution- and laser ablation-based sampling methodologies on the Neoma MC-ICP-MS

In this study we utilize an all-faraday cup detector configuration on the Neoma MC-ICP-MS to perform uranium isotope ratio determinations from certified reference materials and a nuclear fuel precursor material via solution and laser ablation based sampling methodologies. The goal in performing these measurements is primarily to demonstrate that the all-faraday cup method can produce highly precise and accurate isotope ratios even at relatively low signal intensity levels while also developing a preliminary understanding of how the complex interplay between different amplifier resistor levels (e.g. 1011 vs 1013 Ω) and integration times impacts the precision and accuracy of different types of measurements. Our results show that the faraday cups with 1013 Ω resistors in their amplifier feedback loops can be used to produce accurate and relatively precise isotope ratios for ion beams down to ∼5 K cps. However, at the lower end of the signal intensities observed in this study, longer integration times are necessary to mitigate the impact of ion beam instability that can occur during laser ablation based sampling. Despite this potential limitation, the all-faraday cup method is highly versatile as exemplified by the analysis of a collection of uranium reference materials with highly variable uranium isotopic compositions.

An Energy-Efficient Small-Area Configurable Analog Front-End Interface for Diverse Biosignals Recording.

We introduce a fully integrated configurable analog front-end (CAFE) sensor intended to accommodate various types of bio-potential signals in this article. The proposed CAFE is composed of an AC-coupled chopper-stabilized amplifier to effectively reduce 1/f noise and an energy- and area-efficient tunable filter to tune this interface to the bandwidth of various specific signals of interest. A tunable active-pseudo-resistor is integrated into the amplifier's feedback to realize a reconfigurable high-pass cutoff frequency and enhance its linearity, while the filter is designed using a subthreshold-source-follower-based pseudo-RC (SSF-PRC) topology to attain the required super-low cutoff frequency without the need for extremely low biasing current sources. Implemented in TSMC 40 nm technology, the chip occupies an active area of 0.048 [Formula: see text] while consuming 2.47 μW DC power from a 1.2-V supply voltage. Measurement results indicate that the proposed design achieved a mid-band gain of 37 dB, with an integrated input-referred noise ( VIRN) of 1.7 μVrms within 1-260 Hz. The total harmonic distortion (THD) of the CAFE is below 1 % with a 2.4 m Vpp input signal. With a wide-range bandwidth adjustment capability, the proposed CAFE can be used in both wearable and implantable recording devices to acquire different bio-potential signals.

Graphical Approach to Optimization of Maximally Efficient-Gain-Boosted Feedback Amplifiers

It is challenging to design high-gain amplifiers near the maximum oscillation frequency (fmax) of the transistors. This paper presents a comprehensive graphical approach to maximize the gain of feedback amplifiers with maximally efficient gain (GME) conception at near-fmax frequency. The complex gain-plane and the reflection-coefficient-plane are utilized to provide clear insights into both the gain and stability states of the two-port device while boosting GME. An efficient flowchart to synthesize feedback amplifiers is given, which optimizes the GME of a two-port device while ensuring the stability. A 210 GHz power amplifier in 40 nm CMOS was designed and optimized based on the proposed approach. The feedback circuit of the transistor pushes it to become potentially unstable and boosts GME. The measured peak small-signal gain was 10.48 dB at 195.33 GHz. The measured saturation output power and large-signal gain at 210 GHz were 3.04 dBm and 7.08 dB, respectively. The presented method could facilitate terahertz amplifier design.

Normal-mode splitting in an optomechanical system enhanced by an optical parametric amplifier and coherent feedback

Normal-mode splitting (NMS) is an evident signature of strong coupling interactions for observing quantum phenomena, such as optomechanical squeezing and entanglement. In the previous literature, optical parametric amplifier (OPA) and coherent feedback are independently proposed to enhance the NMS. Here, we combine OPA and coherent feedback into a single optomechanical system to enhance the NMS. Controllable parameters, such as input optical power, OPA gain and phase, coherent feedback strength, are varied to observe NMS variations. In particular, we consider positive and negative feedback in terms of the amplitude reflectivity of the beam splitter for coherent feedback. The NMS appears mostly with the positive coherent feedback rather than the negative. Furthermore, the largest mode separation occurs at an OPA phase of approximately rather than zero because the effective cavity detuning changes the effective intracavity round-trip phase, and therefore changes the OPA amplification/deamplification condition. The results indicate that the interplay between OPA and coherent feedback can enhance the NMS with more controllable parameter freedoms. This scheme provides a promising way to increase the optomechanical coupling strength, thereby having potential applications in the ground state cooling of a mechanical oscillator, the preparation of optomechanical quantum states, and the sensitive detection of a weak force.

A novel design procedure of a compact-size X-band shunt feedback amplifier

ABSTRACT This paper describes a high-frequency shunt feedback amplifier. A new design procedure is presented based on practical design steps as well as theoretical aspects, such as sizing the transistor, stabilisation, and selecting the values of feedback elements. The amplifier is designed and fabricated using 0.15 μm GaAs technology. It operates in the 7–10 GHz frequency range, with a small signal gain of 11.5 ± 0.5 dB and input and output return losses of less than 6 dB and 7 dB, respectively. Furthermore, for 1 dB and 3 dB output compression points, the maximum measured values are 23.1 dBm and 23.9 dBm, respectively. Besides, the maximum measured value for Power Added Efficiency (PAE) for 1 dB output compression is 27.13% and 48.6% for 3 dB output compression. In addition, the measured Noise Figure (NF) in the frequency band of interest ranges from 3.7 to 4.1 dB. The chip area of the fabricated amplifier is 1.01 mm2.

A non-pipelined ADC with a GM-R amplifier

A GM-R amplifier is proposed as a residual amplifier to implement a 16-bit two-stage non-pipelined ADC in intermittent signal acquisition applications. Unlike common capacitive feedback amplifiers, residual amplifiers utilize resistor ratios to generate constant gain for small input amplitude ranges and wide temperature ranges. The input circuit of the proposed amplifier consists of two source followers and a bridge resistor, thus converting residual voltages to currents, and the transconductance is the reciprocal of the bridge resistor. The amplifier offset voltage is corrected by a one-time foreground offset calibration, and the gain error is calibrated with the capacitor weights in the first stage. Redundancy is adopted between the two stages to accommodate the residual offset voltage after calibrating the offset voltage of a comparator and the gain variation. A design prototype is implemented in 180 nm CMOS technology, occupies a 0.69 mm2 footprint, and consumes 3.0 mW from 1.8/5 V power supplies. After calibration, it achieves the SNR of 88.2 dB, SNDR of 87.6 dB, and THD of −95.6 dB at 200 kHz sampling rate. The measured differential nonlinearity (DNL) and integral nonlinearity (INL) are −0.62/+0.74 LSB and −1.39/+1.50 LSB, respectively.

Linear Voltage Controlled Oscillator Implementation in Electronically Variable Immittances

New realization schemes of electronically tunable inductor (L) and Frequency-Dependent Negative Resistance (D) type immittances using a Current Feedback Amplifier (CFA) and Multiplication Mode Current Conveyor (MMCC) composite active building block (ABB) are proposed. Applications of the immittances to the design of selective filters and LC-type linear voltage controlled quadrature oscillator (LVCQO) are presented. Experimental results based on PSPICE simulation and hardware design for a linear range of oscillation frequency (fo ~ 13.6MHz) with satisfactory phase-noise figure on the oscillator wave response had been verified. Effects of the Active Building Block (ABB)-nodal imperfections are analyzed to be insignificant. The new ideas in this article are two types of immittance functions realizable in the same topology; appropriate frequency-domain selective responses are also presented with experimentation results.

Improvement of a highly sensitive and specific whole-cell biosensor by adding a positive feedback amplifier

In this study, we designed a Cd2+ whole-cell biosensor with both positive and negative feedback cascade amplifiers in Pseudomonas putida KT2440 (LTCM) based on our previous design with only a negative feedback amplifier (TCM). The results showed that the newly developed biosensor LTCM was greatly improved compared to TCM. Firstly, the linear response range of LTCM was expanded while the maximum linear response range was raised from 0.05 to 0.1 μM. Meanwhile, adding a positive feedback amplifier further increased the fluorescence output signal of LTCM 1.11–2.64 times under the same culture conditions. Moreover, the response time of LTCM for detection of practical samples was reduced from 6 to 4 h. At the same time, LTCM still retained very high sensitivity and specificity, while its lowest detection limit was 0.1 nM Cd2+ and the specificity was 23.29 (compared to 0.1 nM and 17.55 in TCM, respectively). In summary, the positive and negative feedback cascade amplifiers effectively improved the performance of the biosensor LTCM, resulting in a greater linear response range, higher output signal intensity, and shorter response time than TCM while retaining comparable sensitivity and specificity, indicating better potential for practical applications.

Research on the Polygraph: the CMOS Neural Amplifier

The polygraph is an effective piece of equipment to detect if the suspect is lying in order to track down the criminal. The paper simulates and sets up the host part of the polygraph in order to explain how the polygraph works and some fields to use it. And we successfully make a neural amplifier to show the way that the host amplifies neural signals, and has a low passband that can filter out high-frequency signals. The circuit has two parts the folded cascode amplifier DC gain is 64.56, the -3dB bandwidth is about 100kHz and the total current consumption is 4uA and the capacitive feedback amplifier passband gain is 40dB and the passband is from about 3Hz to 5kHz. It is of great value not only in the field of criminal investigation, but also in VR, artificial intelligence (AI), and mental health. Because it can record and let people observe human brain activity and emotional changes. What’s more, with its development of it, it can solve many small crimes automatically, which means police can have more time and energy to deal with difficult cases and society can be more stable.