A low-distortion transconductance amplifier

This paper describes a highly linear and low- distortion, bipolar differential voltage-to-current converter (V-I) circuit that can be used for a number of applications, such as the transconductance stage for mixer circuits and gm-c filter circuits. This circuit is capable of providing a wider linear range of operation and lower total harmonic distortion compared with the conventional emitter-degenerated emitter-coupled differential pair due to the global feed-back technique used. Simulation results show that this circuit can provide 30dB improvement in total harmonic distortion over an operating range from -0.5V to +0.5V. This circuit uses a supply voltage of plusmn2.5V and an emitter degeneration resistor of 600 Omega.