Anwar A. Khan

Current-mode precision rectification

This paper describes a simple and versatile current-mode full-wave precision rectifier circuit using AD844 from Analog Devices. The proposed scheme avoids the use of closely matched resistors and matched current mirrors. The circuit is easy to design and construct from readily available low-cost components and provides excellent precision rectifier performance over a wide band and wide input voltage range. Experimental results are included.

An improved current-mode instrumentation amplifier with bandwidth independent of gain

A modification in current-mode instrumentation amplifier topology proposed in Electronics Letters, vol. 25, p.470-471 (1989) is described, and a detailed analytical analysis is given to show its superiority. The proposed circuit design is simple and easy to construct from readily available IC AD844 from Analog Devices. The proposed circuit features high CMRR without requiring well-matched resistors. Moreover, high differential gain and bandwidth can be achieved simultaneously. Experimental as well as simulation results are given in support of theoretical conclusions. >

Operational floating current conveyor: characteristics, modelling and applications

A new five-port general purpose analogue building block, termed as an operational floating current conveyor (OFCC), is described. The OFCC combines the features of current feedback (CFB) operational amplifier, second generation current conveyor and operational floating conveyor (OFC). A simple implementation scheme of the OFCC is described and its terminal operational characteristics are used to yield a working model. The OFCC is then used as a single block to realize the four main amplifier types and the current conveyors (CCII+ and CCII-). Computer simulation results are presented and discussed.<<ETX>>

Linearized thermistor thermometer using an analog multiplier

A scheme using an analog multiplier that provides an output voltage linearly proportional to the absolute temperature over a wide dynamic range is presented. It has the advantage of being simple and attractive in that the calibration of the output indicating meter does not depend upon the thermistor parameters. Results of measurements in the range 283-493 K are presented. The deviation from the straight-line response amounts to an error of 6% at 283 K and decreases to about 0.6% at 320 K. >

A novel wide range linearization approach for thermistor thermometer

A logarithmic function for response linearization of the thermistor thermometer is presented. A theoretical study of the proposed scheme is presented. A novel and inexpensive circuit configuration for realizing the proposed logarithmic function is described. The approach offers linear temperature/voltage conversion over a wide dynamic range with an output that is independent of fluctuations in the ambient temperature. Test results are given to support the theoretical conclusions.

A novel instrumentation amplifier with reduced magnitude and phase errors

A novel, simple, low-cost modification in the conventional instrumentation amplifier structure is suggested to minimize the magnitude and phase errors. Necessary analytical conditions are obtained to realize maximally flat magnitude and phase responses over a wide frequency range. The effect of the second pole of the op-amps on the circuit stability is presented. The proposed design has the advantage of flat magnitude and phase responses over an extended frequency range. Simulation and experimental results are given to support the theoretical conclusions. >

Linearization of thermistor thermometer

A theoretical study of thermistor response linearization incorporating a logarithmic network-based scheme, as well as conventional methods, is presented. The logarithmic network-based scheme exhibits superior performance over the conventional methods. A novel and inexpensive circuit configuration for realizing the logarithmic transfer function suitable for response linearization is described. The proposed circuit offers linear temperature/voltage conversion over a wide dynamic range with an output which is independent of fluctuations in the ambient temperature. Test results are given to support the theoretical conclusions.

A new integrable composite circuit with improved FET-like characteristics

A new composite circuit comprising five active devices (a JFET and four bipolar transistors) and three passive resistors is described and shown to exhibit FET-like characteristics with much improvement in thermal stability and transfer curve linearity over a wide range of input bipolar voltage. The input resistance of the proposed circuit is, however, equal to that of the FET with the additional advantage that it continues to be high even for positive input voltage. The proposed structure is fully compatible with silicon integrated circuit (IC) technology and may thus be commercially mass-produced as a three-terminal device with its terminals designated as gate, drain, and source.

A novel wide-band differential amplifier

A novel configuration for an op.-amp.-based differential gainblock is presented. The analytical expressions are obtained, and the performance of the proposed circuit is examined in relation to the conventional circuit. Simulation and experimental results are presented which establish the superiority of the proposed differential amplifier over the conventional circuit. Numerical results are given. >

Extending the bandwidth of an instrumentation amplifier

Abstract A new configuration for operational amplifier based instrumentation amplifier is presented. The analytical expressions are obtained and the performance of the proposed circuit is examined in relation to the conventional circuit. Simulation and experimental results are presented which establish the superiority of the proposed instrumentation amplifier topology over the conventional circuit. The effect of second pole of op amps on the circuit stability has also been investigated. Numerical results are given in support of theoretical conclusions.