A system is disclosed for compensating for the offset voltage problem which occurs in certain types of differential amplifiers; a differential amplifier, in the form of an operational amplifier, is provided with two generators of input signals whose difference is to be amplified; further included is...http://www.google.com/patents/US4395681?utm_source=gb-gplus-sharePatent US4395681 - System for compensating the offset voltage of a differential amplifier
