A Low-voltage Current-mode Electronically Controllable Four-quadrant Zero/span Circuit

Abstract

A low-voltage four-quadrant current-mode current-controllable zero/span circuit is discussed. The circuit structure is based on CMOS current follower with adjustable current gain and 4 diodes, without any resistor. The proposed circuit has advantage in such low-voltage architecture biased with as low as ±0.5V power supply. It can generate four-quadrant outputs, without any changing circuit topology. Additionally, its zero and span levels can be independently tuned by electronic method though relative bias currents, where a low-offset output current can be achieved. The total power consumption is approximately 10µW, much lower than a traditional one. Simulation results are shown; it offers good performances of the proposed circuit as depicted. Furthermore, to extend the workability of the proposed zero/span circuit, its application in current-mode Wheatstone bridge to alleviate the offset problem.