Differential Amplifier Research Articles

Kontrol Robot Menggunakan Gerakan Mata Berbasis Sinyal Electrooculography (EOG)

Biomedical technology has now been widely adopted as a means of monitoring the human body in real-time. For example, to detect eye movement. In the medical world, eye movement can be used to determine the type of disease. With the application of human-machine interface (HMI) technology, eyeball movement can be developed in the robotics industry as robot navigation. For example, by moving the eyeball left and right, the robot can interpret the eye signal to move left and right. The interaction between the eyeball movement and the robot is of particular concern in this study. This study aimed to design a measuring instrument for eye movement detection using Electrooculography (EOG) techniques to move a wheeled robot. The EOG measuring instrument consisting of an instrument differential amplifier, a low pass filter, and a high pass filter has been applied in this research. The signal generator technique on EOG is carried out by placing electrodes on three sides of the face, namely forehead (G), left horizontal (H-), right horizontal (H +). The experimental results showed a significant difference between the left and right eye movement amplitude signals. This amplitude is used to classify the movement of the robot wheel towards the left and right. The process of sending robot signals and EOG measuring instruments uses Bluetooth HC-05 serial communication. Based on the research results, it is proven that the robot manages to move left and right according to the eyeball movement.

An ultra-low-power bulk-driven subthreshold super class-AB rail-to-rail CMOS OTA with enhanced small and large signal performance suitable for large capacitive loads

This paper introduces a power-efficient super class-AB bulk-driven (BD) operational transconductance amplifier (OTA) in the subthreshold region suitable for driving a high capacitive load. An improved auxiliary differential amplifier is employed using a cross-coupled connection to the gate of the input core differential pairs and its adaptive biasing BD FVF differential pairs to boost the input core transconductance and slew rate in superclass-AB mode. The utilization of a partial positive feedback operation further improves the open-loop voltage gain, overall effective transconductance, and unity-gain frequency (UGF) with a sufficient phase margin of 93⁰. The Post layout simulation results of the proposed OTA in Cadence DFW-II platform using UMC 0.18 μm technology for a 0.5 V single supply and a capacitive load of 200 pF confirm enhancement of 22 times slew rate, 54.32 dB DC gain, and 75 times UGF achieved by the proposed design over its conventional counterpart with only a narrow increase of 1.19 times in power expenditure.

Analysis, Simulation, and Development of a Low-Cost Fully Active-Electrode Bioimpedance Measurement Module

A low-cost 1 kHz–400 kHz operating frequency fully-active electrode bioimpedance measurement module, based on Howland current source, is presented in this paper. It includes a buffered positive feedback Howland current source, implemented with operational amplifiers, as well as an AD8421 instrumentation amplifier, for the differential voltage measurements. Each active electrode module can be connected to others, assembling a wearable active electrode module array. From this array, 2 electrodes can be selected to be driven from a THS413 fully differential amplifier, activating a mirrored Howland current source. This work performs a complete circuit analysis, verified with MATLAB and SPICE simulations of the current source’s transconductance and output impedance over the frequency range between 1 kHz and 1 MHz. Resistors’ tolerances, possible mismatches, and the operational amplifiers’ non-idealities are considered in both the analysis and simulations. A comparison study between four selected operational amplifiers (ADA4622, OPA2210, AD8034, and AD8672) is additionally performed. The module is also hardware-implemented and tested in the lab for all four operational amplifiers and the transconductance is measured for load resistors of 150 Ω, 660 Ω, and 1200 Ω. Measurements showed that, using the AD8034 operational amplifier, the current source’s transconductance remains constant for frequencies up to 400 KHz for a 150 Ω load and 250 kHz for a 1200 Ω load, while lower performance is achieved with the other 3 operational amplifiers. Finally, transient simulations and measurements are performed at the AD8421 output for bipolar measurements on the 3 aforementioned load resistor values.

RANCANG BANGUN ELEKTROMIOGRAFI PERMUKAAN PORTABEL

Muscle weakness is a condition when one side of the body experiences weakness so that it is difficult to move that part. Muscle weakness is commonly experienced by post-stroke patients or patients with muscle injuries. However, the use of Electromyography can only be used by medical personnel and the cost is quite expensive. Therefore, the manufacture of portable surface electromyography is intended to assist users in knowing the condition of muscle strength. The muscle signal can be read with a surface electrode connected to the Differential Amplifier circuit, then the signal is processed with a series of filter Circuit: LPF, HPF and Notch Filter to reduce noise, and an adder circuit to increase the signal so that it can be read as adc which is connected to raspberry pi and can be connected via Bluetooth. Testing the whole Surface Electromyography tool is able to read and display signals on the raspberry pi and can find out the type of movement using the FFT and MPF methods. The type of flexion motion has an MPF ??value of less than 180Hz and the extension movement has an MPF ??value of more than 180Hz.

Workshops (WS) Workshop 1: Electroencephalogram (EEG) WS1.1. The origin of EEG, recording techniques and quality

EEG records the electrical activity of the cerebral cortex, mainly from large pyramidal neurons close to the surface, and this activity is influenced by subcortical structures. At least 6 cm 2 of synchronised cortical activity is required to be recorded by scalp EEG. Surface electrodes are placed equidistantly over the scalp according to an international convention (10–20 System), ensuring good electrical contact, with electrode impedances <5000 ohms. Each electrode is influenced by both physiologically relevant activity and high amplitude environmental electrical noise, so pairs of electrodes are connected to differential (common-mode rejection) amplifiers to hopefully cancel out the environmental noise and record any differences between the two electrodes. Digital EEG amplifiers then use analogue-to-digital converters to translate the recorded voltage differences into numerical values, requiring an amplitude resolution of at least 12 bits (usually ≥16 bits), and with the number of measurements per second (sampling rate) at least three times the highest frequency being recorded (≥256 Hz). Filtering highlights activity that is biologically relevant, using a bandpass of 0.5–70 Hz for routine diagnostic EEG, but filtering distorts raw data and is no substitute for good technique. Digital EEG recording uses a system reference electrode separate from the 10–20 recording electrodes and stores the voltage measurements for each recording electrode relative to this system reference electrode. This allows reformatting of EEG channels and montages after the recording simply by combining any electrode pair to create the channel. At least longitudinal bipolar, transverse bipolar and referential montages should be used to read EEG. Unfortunately, EEG is commonly misinterpreted, leading to misdiagnosis. Age and state dependency dramatically influence the normal EEG, and there are many variations of normal, especially during drowsiness and sleep. ECG, careful clinical observation and video recording (routine if possible) are required throughout the recording to recognise artefacts and other important changes. For EEG to be useful, comprehensive knowledge, training and experience are required under the supervision of a skilled mentor. When in doubt, it is best to assume that background slowing is related to drowsiness/sleep, and every sharply contoured wave is an artefact or normal variant until proven otherwise.

Reconfigurable and Dense Analog Circuit Design Using Two Terminal Resistive Memory

Metal-oxide based bipolar Resistive RAM (RRAM) is one of the most promising candidates for the future non-volatile data storage. Due to unique properties e.g., small footprint, ability to modulate resistance states in wide ranges dynamically, hysteresis and CMOS compatibility, RRAM can be a fruitful candidate for analog circuit design. However, the recent literature only scratches the surface of this interesting prospect. In this paper, a single RRAM behavior is studied under temperature, voltage and process variations from an analog design standpoint. A comparative study is performed between two analog circuits namely, Common Source (CS) amplifier and differential amplifier with traditional passive resistors and with passive resistors replaced by RRAM along with two other design examples, namely constant $g_m$ g m biasing circuit and active low-pass filter, where RRAM can be integrated into analog circuits. Our study shows that blind swapping of passive resistors with RRAM in analog circuits can actually degrade the performance metrics. We propose techniques such as usage of RRAM Low Resistance State (LRS) to recover the loss. We also note that hyperbolic I-V characteristics of RRAM can inherently improve the linearity of RRAM based analog designs. Simulation results indicate that RRAM based amplifiers can achieve 2X area reduction, about 1.5X higher bandwidth with only $\approx 9\%$ ≈ 9 % reduction in gain. The resistance modulation property of RRAM is applied to realize a source degenerated amplifier with reconfigurable linearity, to a constant transconductance bias circuit to avoid resistance trimming and to design a programmable active low pass filter.

Design and simulation of high-swing fully differential telescopic Op-Amp

This article describes the process of design and simulation of a high-swing fully differential telescopic operational amplifier (Op-Amp). Due to the common gate-common source (CG and CS) cascode structure, the gain is very high. To maximize this gain, the load must also be selected such as two current sources. This circuit has the higher voltage in output than current Op-Amps in accordance with desirable characteristics. The loss of power of this operating amplifier are very low and in milliwatts. With use of a power supply of 1.8 V, it achieves a high-swing 1.2 V, a differential gain of 76.333 dB, ωuGB of 412 MHz, and &gt;50 dB CMRR. This new design through the simulations and analytically shows that the high-swing fully differential telescopic Op-Amp retains its high CMRR even at high frequencies.

Design and simulation of high-swing fully differential telescopic Op-Amp

This article describes the process of design and simulation of a high-swing fully differential telescopic Operational Amplifier (Op-Amp). Due to the Common Gate-Common Source (CG and CS) cascode structure, the gain is very high. To maximize this gain, the load must also be selected such as two current sources. This circuit has the higher voltage in output than current Op-Amps in accordance with desirable characteristics. The loss of power of this operating amplifier are very low and in milliwatts. With use of a power supply of 1.8 V, it achieves a high-swing 1.2 V, a differential gain of 76.333 dB, ω_uGB of 412 MHz, and 50 dB CMRR. This new design through the simulations and analytically shows that the high-swing fully differential telescopic Op-Amp retains its high CMRR even at high frequencies.

Low Voltage Low Power And High Speed OPAMP Design using High-K FinFET Device

In this paper, operational amplifier circuit is designed using model parameters of high-k FinFET in 22nm technology. The conventional design expressions for MOSFET based OPAMP design are fine tuned to design FinFET based OPAMP. The OPAMP design is suitable for use as sub circuit in ADC design as it supports low voltage, high speed and low power dissipation. The transistor geometries are identified so as to achieve high performance and energy efficient OPAMP. Schematic capture is carried out using Cadence tool. From the simulation studies, the designed OPAMP has a unity gain bandwidth of 100 GHz and slew rate is equal to 1V/μS. The maximum power dissipation of differential amplifier circuit is 800nW and hence suitable for all low power analog and digital circuits.

Design optimization guidelines for a class of RF switched-capacitor power amplifiers

An optimization methodology for a popular class of differential RF switched-capacitor power amplifiers exhibiting high efficiency, output power and linearity is presented. Analytical maximization of the output power with respect to component values provides explicit formulas and design guidelines for the amplifier’s core and the tuning of the matching network, that can be used as a starting point for the design and trimming of the power amplifier circuit in an IC design environment.

A 77-GHz High Gain Low Noise Receiver for Automatic Radar Applications

In this paper, a high gain 77-GHz receiver with a low noise figure (NF) was designed and implemented in a 40-nm CMOS process. With the purpose of making better use of active devices, an extra inductor, Ld, is adopted in the new neutralization technique. The three-stage differential low noise amplifier (LNA) using the proposed technique improves the voltage gain and reduces the NF. The receiver design utilizes an active double-balanced Gilbert mixer with a transformer coupling network between the transconductance stage and the switch stage. The flicker noise contribution from the switch MOS transistors is largely reduced due to the low DC current of the switch pairs. The LO signal is provided by an on-chip fundamental voltage-controlled oscillator (VCO) with a tuning range from 70.5 to 78.1 GHz. A conversion gain of 32 dB and a NF of 11.86 dB are achieved at 77 GHz by the designed receiver. The LNA as well as the mixer consume a total DC power of 33.2 mW and occupy a core size of 1 × 0.38 mm2.

Detection of Mercury Ions in Water using a Plastic Optical Fiber Sensor

Research has been carried out on the detection of mercury ions in water using plastic optical fibers. Detection of mercury ions is done by immersing the optical fiber sensor in the HgCl2 solution, where both ends of the sensor are connected to LED and phototransistor. LED as a light source will emit light along with the optical fiber which will be received by the phototransistor. The optical light received by the phototransistor is converted into an electric voltage and given again in the differential amplifier. The output voltage in the form of an analog signal is converted into a digital signal on the Arduino UNO to be read on a computer. The optical fiber as a sensor is made in two configurations, namely U configuration and spiral spring configuration. The jacket and the fiber optic cladding are peeled off and then covered with chitosan. Each configuration will be given a variation of the curve to analyze the characteristics of the sensor. The curvature can cause a large power loss resulting in attenuation of the light intensity of the LED received by the phototransistor. Apart from the effect of indentation on optical fibers, the output voltage measurement results are also influenced by the level of HgCl2 concentration. The best measurement results for mercury ion sensors in water using plastic optical fibers are obtained in a spiral spring configuration with a chitosan cladding with a variation of 6 coils a sensitivity of 104.065 mV/ppm.

Analysis of Limits of CNTFET Devices through the Design of a Differential Amplifier

In this paper, in order to analyze the limits of CNTFET devices, we study the behavior of a differential amplifier based on CNTFET for application between 50 GHz and 500 GHz, determining the highest gain achievable with low noise level. In particular the examined circuit presents a differential input and single ended output, in which each CNTFET is composed by a single CNT, having the same diameter. The analysis is done without considering embedding parasitic effects since our aim is to study the intrinsic limits of CNTFET. We find a solution that is near optimum for gain and noise. In particular we obtain that, using CNTFETs whose channel length is 25 nm, it is possible to reach 27.0 dB gain at 50 GHz and 19.7 dB gain at 500 GHz with a noise spectral power density noise 95 nV/Hz1/2 and 85 nV/Hz1/2 respectively.

A novel memristor emulator design and universal biquad filter application using second generation high swing differential current conveyor transconductance amplifier in 130 nm CMOS process

Memristors have drawn a significant wide spread attention from the research community since past decade due to their high-speed operational potential in analog applications. However, it has been difficult to achieve the memristor behavior directly from solid state solution and state of the art. This work presents a novel emulator design to mimic the memristor behavior. A generic and simple emulator circuit for a voltage controlled memristor is presented using a differential difference current conveyor transconductance amplifier (DDCCTA), which is based on a versatile second-generation current conveyor methodology. A high-swing (up to ±600 mA at the output) and low power implementation design effort for DDCCTA is kept in 130 nm RF-CMOS process with dual power supply mode. The functional simulations have been performed in SPICE environment using Advanced Design System (Keysight Technology), which showed a good alignment to the memristor emulator’s I-V characteristic at 1 KHz and 10 KHz. Proposed DDCCTA then implements the memristor operation with compatible specifications. Finally, the memristor operation and potential has been verified by its application in high-speed active filter operations. A universal biquad section has been presented which employs the designed memristor emulator, with 30 mW of power dissipation with ±1.5 V supply.

Electronically Tunable Full Wave Precision Rectifier Using DVCCTAs

This work presents a voltage mode scheme of a full-wave precision rectifier circuit using an analog building block differential voltage current conveyor transconductance amplifier (DVCCTA) including five NMOS transistors. The proposed design is essentially suited for low voltage and high-frequency input signals. The operation of the proposed rectifier design depends upon the region of operation of NMOS transistors. The output waveform of the presented rectifier design can be made electronically tunable by controlling the bias voltage. The functional correctness and verification of the presented design are performed using 0.25-µm TSMC technology under the supply voltage of ±1.5 V. The absence of a resistor leads to a minimal parasitic effect. To obtain further insight on the robustness of the circuit, a Monte Carlo simulation and corner analysis are also presented. The circuit is verified experimentally by incorporating a breadboard model with the help of commercially available ICs CA3080 (operational transconductance amplifier) and AD844AN (current feedback operational amplifier) and offers remarkable compliance with both theoretical and simulation outcomes. The presented design has been laid out on Cadence virtuoso, which consumes a chip area of 9044 µm2.

A novel design for voltage inverting metamutator and its applications

This paper presents a novel structure of a versatile 4 port network that is used as a voltage inverting metamutator (VIM). The desired port relationships of proposed structure are obtained through proper interconnection of differential amplifiers, current mirrors and an inverting stage. The port relations are verified through both small signal analysis and simulations using 180 ​nm generic process design kit (gpdk) in Cadence Virtuoso tool. The performance of the proposed VIM is also examined by performing corner analysis and Monte Carlo simulations. By using proper port terminations, the proposed VIM is configured as current mode universal Filter, transconductance amplifier, transimpedance amplifier and memristor. All these applications are also verified for functionality.

A 0.6-V VDD W-Band Neutralized Differential Low Noise Amplifier in 28-nm Bulk CMOS

This letter presents a W-band low-power and high-gain differential low noise amplifier (LNA) fabricated in 28-nm bulk CMOS technology. This LNA operates at a 0.6-V supply voltage ( V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><b>DD</b></sub> ) to achieve low power consumption and respond to the low-voltage regime anticipated in future CMOS technology nodes. To obtain sufficient voltage headroom and mitigate the Miller effect, this LNA employs neutralized common source (CS) instead of cascode topology in each stage. The common-mode instability introduced by CS neutralization is reduced by making the secondary coil of each transformer (except the final one) center-tapped with resistors. The stability factor (K) and measure (B1) at a single-stage common mode are improved from 0.59 to 126 and from -0.14 to 0.6, respectively. In addition, each stage of this LNA uses only one transformer for conjugate matching, without any capacitor to minimize the passive loss. This LNA consists of five stages and achieves a power gain of 25 dB over 81-91 GHz (BW <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3dB</sub> ) and a minimum noise figure (NF) of 6 dB at 85 GHz with power consumption of 15 mW and a silicon core area of 0.19 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .

Facile and Low Cost Temperature Compensated Humidity Sensor and Signal Conditioning System

Most relative humidity sensors are resistive or capacitive sensors. It’s a fact that the resistance and capacitance of a vast majority of such sensors also depend on the surrounding temperature and a change of temperature can cause significant errors in the final reading of relative humidity. This fact of temperature dependence is scarcely investigated in development of humidity sensors. In this work, a very simple temperature compensation method has been developed that automatically eliminates the effect of change in temperature from the final output without requiring separate measurement of temperature or any data processing. Amorphous polyethylene oxide (PEO) was used as the active material for humidity sensor owing to its high sensitivity and almost linear response. Interdigitated type sensor electrodes (IDE) were fabricated using reverse offset printing on glass substrate and the active layer was deposited through spin coating. An identical twin sensor was fabricated with the same parameters and was additionally encapsulated form the open environment. The dummy sensor was used as opposing pair with the active sensor in a bridge configuration to achieve temperature compensation. The bridge sensitivity was recorded to be ~2.9 mV/%RH that was further improved to 100 mV/%RH using a differential instrumentation amplifier based signal conditioning circuit. The sensor system was deployed in a real-life relative humidity measurement with changing temperature that returned a remarkable accuracy of 98.76%. The error due to temperature dependence reduced from 22.4% to just 1.24%. The transient response time of the sensor was found to be ~2.4 s.

Design Trade-Offs in Common-Mode Feedback Implementations for Highly Linear Three-Stage Operational Transconductance Amplifiers

Fully differential amplifiers require the use of common-mode feedback (CMFB) circuits to properly set the amplifier’s operating point. Due to scaling trends in CMOS technology, modern amplifiers increasingly rely on cascading more than two stages to achieve sufficient gain. With multiple gain stages, different topologies for implementing CMFB are possible, whether using a single CMFB loop or multiple ones. However, the impact on performance of each CMFB approach has seldom been studied in the literature. The aim of this work is to guide the choice of the CMFB implementation topology evaluating performance in terms of stability, linearity, noise and common-mode rejection. We present a detailed theoretical analysis, comparing the relative performance of two CMFB configurations for 3-stage OTA topologies in an implementation-agnostic manner. Our analysis is then corroborated through a case study with full simulation results comparing the two topologies at the transistor level and confirming the theoretical intuition. An active-RC filter is used as an example of a high-linearity OTA application, highlighting a 6 dB improvement in P1dB in the multi-loop implementation with respect to the single-loop case.

High sensitive, linear and thermostable pressure sensor utilizing bipolar junction transistor for 5 kPa

Research of pressure sensor chip utilizing novel electrical circuit with bipolar-junction transistor-based (BJT) piezosensitive differential amplifier with negative feedback loop (PDA-NFL) for 5 kPa differential range was done. The significant advantages of developed chip PDA-NFL in the comparative analysis of advanced pressure sensor analogs, which are using the Wheatstone piezoresistive bridge, are clearly shown. The experimental results prove that pressure sensor chip PDA-NFL with 4.0 × 4.0 mm2 chip area has sensitivity S = 11.2 ± 1.8 mV/V/kPa with nonlinearity of 2KNLback = 0.11 ± 0.09%/FS (pressure is applied from the back side of pressure sensor chip) and 2KNLtop = 0.18 ± 0.09%/FS (pressure is applied from the top side of pressure sensor chip). All temperature characteristics have low errors, because the precision elements balance of PDA-NFL electric circuit was used. Additionally, the burst pressure is 80 times higher than the working range.