A new transresistance-mode instrumentation amplifier with low number of MOS transistors and electronic tuning opportunity

Abstract

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 0.18 mu m TSMC CMOS parameters are included to conform the validity of the theoretical analysis. Despite extremely simple structure, its input and output impedances are 1.93 and 1.68 k Omega, respectively. Time domain analysis shows that for an input signal of 20 mu A peak to peak, maximum value of THD is 4.5% for direffent frequencies. Monte Carlo simulation is also carried out, which proves robust performance of the proposed IA against mismatches. The required chip area is only 17.1 x 36.9 mu m(2).