Low temperature coefficient input offset voltage trim with digital control

摘要

Low temperature coefficient input offset voltage trim with digital control for bipolar differential transistor amplifiers. The differential input pair of transistors are biased with a current proportional to absolute temperature. Trim current components are generated which also are proportional to absolute temperature and selectively coupled to at least one of the resistive loads to compensate for the original input offset. Control of the coupling of the trim current components preferably is by way of a control word written to and held in a control register. Use of an R-2R ladder using equal trim currents controllably coupled to the nodes of the ladder provide a binary progression in available trim currents. Other embodiments are also disclosed.