A linear transconductance amplifier obtained by realizing a floating resistor

A novel circuit-design technique for bipolar and CMOS linear transconductance amplifiers is presented. The proposed linear transconductance amplifier consists of a differential pair of constant-current-biased transistors with a degeneration resistor and emitter- or source-followed-augmented current mirrors. The fundamental characteristics of the bipolar linear transconductance amplifier at a 1.9 V supply voltage are verified using bipolar transistor arrays and discrete resistors. The obtained linear input-voltage range is 320 mV r.m.s. (=0.905 V/sub p-p/ for less than 1% total harmonic distortion (THD) or 285 mV r.m.s. (=0.806 V/sub p-p/ for less than 0.1% THD when the input frequency is 1 kHz.