Differential Amplifier Research Articles

Ion‐Selective Mobility Differential Amplifier: Enhancing Pressure‐Induced Voltage Response in Hydrogels

Piezoionics is an emerging mechanical‐electrical energy conversion paradigm that enables self‐powered sensing systems for next‐generation intelligent wearable electronics. However, there are currently no rational design approaches to enhance the stimulus response of piezoionic devices. Here, we present a strategy using crown ether as ion‐selective mobility differential amplifiers for enhancing the pressured‐induced voltage response in ionic polyvinyl alcohol (PVA) hydrogels. The crown ether grafted PVA (PVA‐CE) hydrogel prototype achieves a 30‐fold amplified piezoionic coefficient of 1490 nV Pa−1 within 0 – 1 kPa, compared to 49 nV Pa−1 of the unmodified PVA. The PVA‐CE exhibits an ultra‐low pressure detection limit of 0.2 Pa with a fast response time of 18.1 ms. Leveraging these properties, we further demonstrate a human somatosensory network analogous PVA‐CE piezoionic skin using arrayed pressure sensing. These capabilities hold great promise for emerging healthcare applications such as synthetic biology, soft robotics, and beyond.

Ion-Selective Mobility Differential Amplifier: Enhancing Pressure-Induced Voltage Response in Hydrogels.

Piezoionics is an emerging mechanical-electrical energy conversion paradigm that enables self-powered sensing systems for next-generation intelligent wearable electronics. However, there are currently no rational design approaches to enhance the stimulus response of piezoionic devices. Here, we present a strategy using crown ether as ion-selective mobility differential amplifiers for enhancing the pressured-induced voltage response in ionic polyvinyl alcohol (PVA) hydrogels. The crown ether grafted PVA (PVA-CE) hydrogel prototype achieves a 30-fold amplified piezoionic coefficient of 1490 nV Pa-1 within 0 - 1 kPa, compared to 49 nV Pa-1 of the unmodified PVA. The PVA-CE exhibits an ultra-low pressure detection limit of 0.2 Pa with a fast response time of 18.1 ms. Leveraging these properties, we further demonstrate a human somatosensory network analogous PVA-CE piezoionic skin using arrayed pressure sensing. These capabilities hold great promise for emerging healthcare applications such as synthetic biology, soft robotics, and beyond.

A chopper amplifier with adaptive biasing OTA for biomedical applications, featuring high gain and CMRR.

This paper presents a design of fully differential chopper amplifier employing the flipped voltage follower (FVF) adaptive biasing technique, focusing on its potential use in biopotential recording applications. The suggested architectural OTA incorporates self-cascoded current mirrors (SCCMs) as the active load to achieve a substantial output swing. The FVFs based adaptive biasing approach for the differential input stage boosts extra current and enhances gain and dynamic characteristics. The chopper amplifier attains a common mode rejection ratio (CMRR) of more than 100 dB through the strategic utilization of chopper modulators and pseudo-resistors. Additionally, this device exhibits characteristics such as accurate and stable gain, high input impedance, and a compact physical footprint. The present study also includes a comparison between the suggested structure and the bio-potential amplifiers discussed in the existing literature. This comparison is based on key metrics such as gain, input referred noise (IRN), CMRR, and input impedance (Zin). The proposed structure yielded a gain of 63.72 dB, an IRN of 0.07nVrms, a CMRR of 127.97 dB and a Zin of 1.54 GΩ. The bio-potential chopper amplifier under consideration was constructed and simulations were performed by utilizing the Cadence Virtuoso Spectre simulator tool at 180 nm CMOS technology node.

Piezoelectric MEMS microphones based on rib structures and single crystal PZT thin film

In this study, a controllable mass‒frequency tuning method is presented using the etching of rib structures on a single-crystal PZT membrane. The rib structures were optimized to reduce the membrane mass while maintaining the stiffness; therefore, the center frequency could be increased to improve the low-frequency bandwidth of microphones. Additionally, this methodology could reduce the modulus and improve the sensitivity for the same resonant frequency, which typically indicates the maximum acoustic overload point (AOP). The PZT film was chosen because of its greater density; the simulation results showed that PZT could provide a greater frequency tuning (24.9%) compared to that of the AlN film (5.8%), and its large dielectric constant enabled the optimal design to have small electrodes at the maximum stress location while mitigating the sacrificial capacitance effect on electrical gain. An analytical model of rib-structure microphones was established and greatly reduced the computing time. The experimental results of the impedance tests revealed that the center frequencies of the six microphones shifted from 74.6 kHz to 106.3 kHz with rib-structure inner radii ranging from 0 μm to 340 μm; this result was in good agreement with the those of the analytical analysis and finite element modeling. While the center frequency greatly varied, the measured sensitivities at 1 kHz only varied within a small range from 22.3 mV/Pa to 25.7 mV/Pa; thus, the membrane stiffness minimally changed. Moreover, a single-crystal PZT film with a (100) crystal orientation and 0.24-degree full width at half maximum (FWHM) was used to enable differential sensing and a low possibility of undesirable polarization. Paired with a two-stage differential charge amplifier, a differential sensing microphone was experimentally demonstrated to improve the sensitivity from 25.7 mV/Pa to 36.1 mV/Pa and reduce the noise from −68.2 dBV to −82.8 dBV.

Investigation of Superconducting Quantum Interference Readout Electronics Based on Self-Feedback Differential Low-Noise Amplifier

Investigation of Superconducting Quantum Interference Readout Electronics Based on Self-Feedback Differential Low-Noise Amplifier

Research on Techniques for Enhancing the Speed of Low-Power Operational Amplifier

In the context of low utilization, this paper explores various techniques for enhancing the speed of operational amplifier (OA). The main text delves into three methods to gain equilibrium: fully differential operational amplifier (FDA), twostage operational transconductance amplifier (OTA), and a novel high-speed calculation system architecture employing a “rhombus crystal tube.” The FDA improves speed by minimizing noise and enhancing bandwidth and output voltage swing, without increasing power consumption. The design of the two-stage OTA combines the characteristics of a differential amplifier and a telescopic amplifier, optimizing gain and slew rate through Miller compensation and noise gain manipulation, thereby achieving high-speed performance. A novel high-speed operational amplifier structure employs diamond transistors to supply substantial current for capacitor charging, enhancing the slew rate and overall speed. Throughout the text, these methods are presented as a means to jointly promote high speed, low power consumption, and the handling of a significant number of transistors. To further increase the speed, the size of the microcrystalline tube is crucial. The research direction is outlined, and while the design equipment is in the foreground, there remains room for progress, especially in applications for large-scale electrical models. Future research aims to enhance the power efficiency of circuits, making them more practical and efficient. This study provides valuable insights into balancing power consumption and speed in advanced electronic devices.

16-nW 0.5-V low-pass filter for bio-signal applications

A low-voltage, ultra-low power fully differential low-pass filter for bio-signal applications using multiple-input fully differential operational transconductance amplifiers (OTA) is presented in this article. The multiple inputs of OTA can be achieved using multiple-input dynamic threshold MOS transistor (MIDT-MOST) technique. The novelty of this work is to exhibit the proposed filter using multiple-input OTAs, which leads to a reduction in the number of active OTAs and power consumption. The fourth-order low-pass filter that is cascaded by two second-order filters has been presented. The fourth-order low-pass filter is designed and simulated in the Cadence environment using the 0.18 μm CMOS technology from TSMC at a supply voltage of 0.5 V. The simulation results show that the filter consumes 16 nW of power at a bandwidth of 110 Hz, has a total harmonic distortion (THD) of 1 % at 204.96 mV input amplitude, and provides dynamic range of 69.24 dB. These results indicate that the proposed low-pass filter can be applied to bio-signal processing applications.

Laser-fibre interface for single-particle detector amplification and transportation

Abstract Single quantum particle detectors (e.g. photo-multiplier tubes and electron multipliers) produce ns-output pulses that time-correlate to particles that enter them. The detector output pulses usually require amplification at source, before being sent to counting electronics for analysis. A laser-based transport system is detailed here that converts the detector output into light pulses that are injected into single mode fibre. Pulse delivery is then by fibre, so that electrical interference from the laboratory environment and earth grounding loops are eliminated. A fast photodiode and differential amplifier converts the signal exiting the fibre into a voltage pulse for subsequent timing experiments.

A compact and tunable active inductor-based bandpass filter with high quality factor for Wireless LAN applications

A fully-differential compact and tunable second-order bandpass filter (BPF) with high quality factor using a novel active inductor (AI) has been proposed for 3.6 GHz WLAN applications. The proposed AI employs a differential amplifier as a feedforward transconductor and a common-source (CS) transistor as a feedback transconductor in a symmetrical configuration. The combination of a cascode scheme and a resistor in the feedback path enhances the quality factor of the AI, thereby increasing the mid-band gain of the BPF. In order to achieve independent tuning of both the center frequency and mid-band gain of the BPF, a varactor capacitor is utilized. The proposed second-order BPF is designed with a center frequency and a bandwidth of 3.675 GHz and 10 MHz, respectively. Post-layout simulation, process corner, and temperature sweep analysis results are conducted with 65 nm CMOS technology at 1.2 V supply voltage. The proposed filter has a tuning range of 3.655–3.695 GHz and attains a mid-band gain of 67.5 dB, a noise figure of 14.5 dB, and a 1-db compression point of −12.39 dBm. Additionally, the BPF consumes a DC power of 1.22 mW and occupies an active area of only 8.85 μm × 10.3 μm.

A Design of high-low voltage compatible fully differential operational amplifier

A Design of high-low voltage compatible fully differential operational amplifier

A novel tunable capacitively-copuled instrumentation amplifier with 14.4 nV/ [formula omitted] z) noise and 190.47 nW micro-power for ECG applications

This paper describes a low-power, low-noise capacitively-coupled instrumentation amplifier (CCIA) designed for capturing biopotential signals. The main advantage of proposed design are as (i) CCIA based on new IA has been proposed, (ii) the lower cutoff frequency has been improved by adding MOS based resistor, (iii) gm enhancement circuit is added in operational transconductance amplifier (OTA) based fully differential difference amplifier (FDDA)to improve gain and bandwidth. The DC electrode-offset voltage is reduced and the input impedance is increased by using feedback mechanism. Cadence EDA tool is used to analyze the findings of the proposed CCIA's in 0.18 μm, CMOS technology with a 1.8 V power supply. The proposed CCIA architecture has an adjustable mid-band gain from 52.55 to 61.11 dB for bias voltage ranges from 0.1 to 0.6 V, frequency range of 0.06 Hz–1.72 kHz, and a CMRR of 122 dB. The proposed CCIA has a total power dissipation of 190.47 nW and equivalent input referred noise (IRN) of 14.4 nV/sqrtHz at 0.01 Hz. It only occupies 0.01 mm2 of core area. To assess the robustness of suggested design, PVT analysis, post layout simulation and a comparison with previously published works demonstrates the competence of the design.

A Low-Power Optoelectronic Receiver IC for Short-Range LiDAR Sensors in 180 nm CMOS.

This paper presents a novel power-efficient topology for receivers in short-range LiDAR sensors. Conventionally, LiDAR sensors exploit complex time-to-digital converters (TDCs) for time-of-flight (ToF) distance measurements, thereby frequently leading to intricate circuit designs and persistent walk error issues. However, this work features a fully differential trans-impedance amplifier with on-chip avalanche photodiodes as optical detectors so that the need of the following post-amplifiers and output buffers can be eliminated, thus considerably reducing power consumption. Also, the combination of amplitude-to-voltage (A2V) and time-to-voltage (T2V) converters are exploited to replace the complicated TDC circuit. The A2V converter efficiently processes weak input photocurrents ranging from 1 to 50 μApp which corresponds to a maximum distance of 22.8 m, while the T2V converter handles relatively larger photocurrents from 40 μApp to 5.8 mApp for distances as short as 30 cm. The post-layout simulations confirm that the proposed LiDAR receiver can detect optical pulses over the range of 0.3 to 22.8 m with a low power dissipation of 10 mW from a single 1.8 V supply. This topology offers significant improvements in simplifying the receiver design and reducing the power consumption, providing a more efficient and accurate solution that is highly suitable for short-range LiDAR sensor applications.

Artificial Amacrine Retinal Circuits.

Event-based imaging represents a new paradigm in visual information processing that addresses the speed and energy efficiency shortcomings inherently present in the current complementary metal oxide semiconductor-based machine vision. Realizing such imaging systems has previously been sought using very large-scale integration technologies that have complex circuitries consisting of many photodiodes, differential amplifiers, capacitors, and resistors. Here, we demonstrate that event-driven sensing can be achieved using a simple one-resistor, one-capacitor (1R1C) circuit, where the capacitor is modified with colloidal quantum dots (CQDs) to have a photoresponse. This sensory circuit emulates the motion-tracking function of the biological retina, in which the amacrine cells in the bipolar-to-ganglion synaptic pathway produce a transient spiking signal only in response to changes in light intensity but remain inactive under constant illumination. When extended to a 2D imaging array, the individual sensors work independently and output signals only when a change in the light intensity is detected; hence, the concept of the frame in image processing is thereby removed. In this work, we present the fabrication and characterization of a CQD photocapacitor-based 1R1C circuit that has a spectral response at 1550 nm in the short-wave infrared (SWIR). We report on the key performance parameters including peak responsivity, noise, and optical noise equivalent power and discuss the operating mechanism that is responsible for spiking responses in these artificial retinal circuits. The present work sets the foundation for expanding the bioinspired vision sensor capability toward midwave infrared (MWIR) and long-wave infrared (LWIR) spectral regions that are invisible to human eyes and mainstream semiconductor technologies.

Low Power CMOS Differential Amplifiers through ACM Model: Process Variations and Yield Prediction

Low Power CMOS Differential Amplifiers through ACM Model: Process Variations and Yield Prediction

Cryogenic bipolar low noise dc amplifier for low frequency applications

A low-noise bipolar differential dc amplifier was studied at temperatures of 300 and 77 K. It was shown that to ensure the best amplifier performance in terms of noise figure when the operating temperature decreases from 300 to 77 K, it is advisable to use the transistor in the mode of low currents not exceeding 2 mA. It has been established that lowering the operating temperature to 77 K leads to a decrease in the input resistance of the amplifier from a value of several kiloohms to 100 Ohms, the dynamic range increases from 80 to 85 dB, and the harmonic coefficient increases from 0.09% to 1%. In addition, lowering the operating temperature to 77 K has a significant effect on the noise properties of the amplifier: the spectral density of voltage noise decreases from 1 to 0.4 nV/Hz1/2, the spectral density of current noise increases from 2.5 to 9 pA/Hz1/2, while also The threshold frequencies of 1/f noise increase: for voltage from (0.1...10) to 20 Hz and for current from (10...100) to 1000 Hz. The possibility of using an amplifier for low-temperature measurements of samples with low input resistance is substantiated.

Stabilized voltage source inverter for sensitive loads in nuclear installations

The present paper proposes a novel design of a stabilized single-phase voltage-source inverter with pure sinusoidal output voltage for photovoltaic systems employed for feeding sensitive loads in nuclear installations. Such types of loads require a voltage source with quite stabilized magnitude and frequency and pure sinusoidal shape that is free from higher-order harmonics. The inverter is based on an H-bridge four insulated gate bipolar transistors (IGBTs) with gate drivers and optocoupler isolators. A control system based on a fast DSP unit and a microcontroller is designed for cancelation of the higher-order harmonics to produce a pure sinusoidal output with almost zero total harmonic distortion (THD). The sinusoidal purity, frequency and magnitude stabilization are achieved through pulse width modulation (PWM) controlled by a fast-response feedback system that measures the time wave form of the output voltage applied to the load and then calculates the THD, frequency and amplitude. The sinusoidal shaping is performed with aid of a sinusoidal shaping filter (SSF) to fasten the operation of higher-order harmonic cancellation. The frequency measurement is achieved through a frequency counter whereas the amplitude measurement is carried out through a differential amplifier that amplifies the difference between the output voltage of the inverter (while being applied to the load) and reference voltage that determines the desired amplitude. A prototype of the entire system of the proposed voltage-source inverter is fabricated for experimental evaluation of its performance. It is shown through simulation and experimental work that the proposed control system of the inverter output voltage is able to stabilize both the amplitude and frequency of the voltage applied to the load irrespective of the load impedance. Also, it is shown that the THD of the output voltage is -57dB\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$-57 \ ext{ dB}$$\\end{document} (0.00025%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$0.00025 \\%$$\\end{document}), which is almost zero. Moreover, the switching losses are considerably reduced and can be negligible owing to the use of the appropriate IGBTs. The efficiency of the proposed inverter is obtained by simulation taking into account all types of losses. Also, the dependence of the inverter efficiency on the load current is investigated. The average efficiency of the proposed voltage-source inverter is shown to be higher than 97%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$97\\%$$\\end{document}.

A Novel Dung Beetle Optimization Approach for Automatic CMOS Analog Circuit Design

The main objective of the automated circuit sizing technique is to deal with the challenges of design tradeoffs in analog circuit design with improved accuracy and efficacy. Analog circuit design represents a multi-objective optimization challenge, where designers must properly balance various performance factors such as input and output impedance, power dissipation, area, unity-gain bandwidth, slew rate, and open-loop DC gain. Traditional design equations provide a sizing of differential amplifier MOS transistors, further optimization can be achieved through the application of meta-heuristic search techniques. Meta-heuristic search techniques can be used as local optimizers in a smaller search area to improve the optimization of design parameters. The differential amplifier circuit with current mirror load is optimized through the application of the Dung Beetle Optimization (DBO) algorithm. By using an evolutionary algorithm called DBO, all the required parameters were achieved with the least amount of transistor area and power dissipation when compared to the results of the Seeker Optimization Algorithm (SOA), Opposition based Harmony Search Algorithm (OHS), craziness-based particle swarm optimization (CRPSO), and Cuckoo Search (CS) algorithms.

Design and Analysis of High Gain Dual Stage Op-amp in Cadence 180 nm Technology

Abstract: Operational amplifier contains basic current mirror and dual input differential amplifier. Basic Current mirror is an electronic circuit which contains two transistors. The operation of the current mirror is that whenever current is applied to drain of one of the transistors with some magnitude same current will produce at the output of another transistor, hence the name mirror of the input signal. Operational amplifier contains two legs- inverting leg, non- inverting leg. If signals are applied to inverting and non-inverting legs , operational amplifier used as an amplifier and comparator or adder or subtractor. A two stage operational amplifier consists of a differential amplifier at the input stage.While the second stage is a high gain stage biased by the output of differential amplifier.

Millimeter-Wave Band Electro-Optical Imaging System Using Polarization CMOS Image Sensor and Amplified Optical Local Oscillator Source.

In this study, we developed and demonstrated a millimeter-wave electric field imaging system using an electro-optic crystal and a highly sensitive polarization measurement technique using a polarization image sensor, which was fabricated using a 0.35-µm standard CMOS process. The polarization image sensor was equipped with differential amplifiers that amplified the difference between the 0° and 90° pixels. With the amplifier, the signal-to-noise ratio at low incident light levels was improved. Also, an optical modulator and a semiconductor optical amplifier were used to generate an optical local oscillator (LO) signal with a high modulation accuracy and sufficient optical intensity. By combining the amplified LO signal and a highly sensitive polarization imaging system, we successfully performed millimeter-wave electric field imaging with a spatial resolution of 30×60 µm at a rate of 1 FPS, corresponding to 2400 pixels/s.

Bioimpedance measurement device based on an active terminated current source and a four-point measurement technique

In this paper, a low-cost fully compact differential bioimpedance-monitoring front-end based on a precision Voltage-Controlled-Current-Source (VCCS) coupled with high input impedance differential voltage measurement is depicted. This system uses a high input-impedance discrete differential amplifier to allow integrated voltage measurement for 2 or 4 wires measurement methods. The low cost aspect of the devices, its reduced size (portable) and its reconfigurability allow for a wide prospect of applications in environment monitoring or biomedical embedded devices.