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In this paper, a new current-mode instrumentation amplifier is presented using a single current differencing current controlled current conveyor building block and one grounded resistor. The proposed instrumentation amplifier (IA) can easily be cascaded due to the possession of low impedance current input, and high impedance current output. It offers a high differential gain (73.35 dB) and high bandwidth (BW), 44.8 MHz. Moreover, the common-mode rejection ratio (CMRR) is also very high (93.58 dB), and CMRR BW 5.5 kHz. Power dissipation is found to be low at 132 µW. Furthermore, the electronic tuning of gain is the added feature of the circuit. The non-ideality performance of IA is investigated. The proposed IA functionality is verified through the Cadence ORCAD PSPICE simulator using 0.18 µm TSMC (Level 7) technology parameters. The circuit's workability has also been presented experimentally using commercially available current feedback operational amplifier ICs AD844. Comparison of the performances such as differential gain, BW, CMRR, power consumption, and ease of cascading is reported. [ABSTRACT FROM AUTHOR]

Design and simulation of an improved recycling folded cascode (RFC) operational transconductance amplifier (OTA) is presented. The new idea is based on minor changes in the conventional structure. Our improved amplifier is capable to enhance DC gain and unity gain bandwidth (UGBW) in the same −3dB frequency as for RFC structure. Moreover, fast-settling time, input-referred noise, total harmonic distortion (THD) and performances of power supply rejection ratio (PSRR) and common mode rejection ratio (CMRR) are also improved. Simulation results in 90 nm CMOS process indicate that the proposed amplifier has about 2 times the unity gain bandwidth (360 versus 175 MHz) and also has twice gain boosting (68.6 versus 62.5 dB) in the same −3 dB frequency and capacitor load of 10 pF @1.2 V power supply. The results also demonstrate a good figure of merit (FOM), and low sensitivity of temperature and power supply variations for the proposed amplifier. [ABSTRACT FROM AUTHOR]

This paper examines the closed-loop characteristics of the basic Current-Feedback Operational Amplifier (CFOA), and in particular, the dynamic response. Additionally, it also examines the design and advantages of the CFOA regarding its ability to provide a significantly constant closed-loop bandwidth for closed-loop voltage gain. Secondly, the almost limitless slew–rate provided by the class AB input stage that makes it superior to the voltage-mode operational amplifier (VOA) counterpart. Additionally, this paper also concerns the definitions and measurements of the terminal parameters of the CFOA, regarded as a ‘black box’. It does not deal with the way that these parameters are related to the properties of the active passive and active components of a particular circuit configuration. Simulation is used in terminal parameter determination: this brings with it the facility of using test conditions that would not normally prevail in a laboratory test on silicon implementations of the CFOAs. Thus, we can apply 1mA and 1mV test signals from, respectively, infinite and zero source impedances that range in frequency from d.c to some tens of GHz. Also, we assume the existence of resistors with identical Ohmic value and very high value ideal capacitors. Where appropriate, practical test methods are referred to physical laboratory prototypes. [ABSTRACT FROM AUTHOR]

In this paper, the simplest possible electronically adjustable transresistance-mode (TRM) instrumentation amplifier (IA) using only eight MOS transistors is presented. Extremely simple structure of the proposed IA leads to a wide bandwidth and robust performance against mismatches and parasitic capacitances. Of more interest is that the differential-mode gain of the proposed IA can be electronically varied by control voltages. Post-layout and pre-layout simulation results based on 0.18m TSMC CMOS parameters are included to confirm the validity of the theoretical analysis. Despite extremely simple structure, its input and output impedances are 1.93 and 1.68k, respectively. Time domain analysis shows that for an input signal of 20A peak to peak, maximum value of THD is 4.5% for different frequencies. Monte Carlo simulation is also carried out, which proves robust performance of the proposed IA against mismatches. The required chip area is only . [ABSTRACT FROM AUTHOR]

Abstract: In this paper the authors analyze the conventional current-feedback operational amplifier (CFOA) in terms of common-mode-rejection ratio (CMRR) performance, and having identified the mechanism primarily responsible for the CMRR, they propose two new architecture CFOAs. These new CFOAs are further developed, and modified to provide improved bandwidth, AC gain accuracy and high CMRR performance. The key features of the two proposed new CFOAs are the designs of the internal voltage followers which have two separate biasing currents with a similar dynamic architecture to that of the conventional CFOA. The magnitude of one bias current determines the value of the maximum CMRR, and the second can be used to maximize bandwidth. [Copyright &y& Elsevier]

Despite excellent high frequency and high speed performance, current-feedback operational amplifiers (CFOAs) generally exhibit poor common-mode rejection (CMRR) properties, which limit their utility [Analogue IC design: The current-mode approach, IEE Circuits and Systems Series, Peter peregrinus, 1990]. A novel current feedback operational amplifier (CFOA) with improved performance is presented. The proposed CFOA has a new current-cell [Novel current-feedback operational amplifier Design Based on a floating circuit technique, IEE Colloquium on Analogue Signal Processing, 1998], to bias the entire circuit, which achieves an incremental output resistance twice that of the well-known "Wilson" circuit. Simulation results of this new CFOA architecture indicate that the amplifier exhibits performance characteristics superior to those obtained with an established input architecture: in particular, the CMRR (common-mode rejection ratio) is 91 dB, and the d.c. offset voltage less than 26 μV. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents an ultra low voltage, high performance Operational Transconductance Amplifier (OTA) and its application to implement a tunable Gm-C filter. The proposed OTA uses a 0.5V single supply and consumes 60μw. Employing special CMFF and CMFB circuits has improved CMRR to 138dB in DC. Using bulk driven input stage results in higher linearity such that by applying a 500mvp–p sine wave input signal at 2MHz frequency in unity gain closed loop configuration, third harmonic distortion for output voltage is −46dB and becomes −42.4dB in open loop state for 820mvp–p output voltage at 2MHz. DC gain of the OTA is 47dB and its unity gain bandwidth is 17.8MHz with 20pF capacitance load due to both deliberately optimized design and special frequency compensation technique. The OTA has been used to realize a wide tunable Gm-C low-pass filter whose cutoff frequency is tunable from 1.4 to 6MHz. Proposed OTA and filter have been simulated in 0.18μm TSMC CMOS technology with Hspice. Monte Carlo and temperature dependent simulation results are included to forecast the mismatch and temperature effects after fabrication process. [Copyright &y& Elsevier]