Offset correction circuit for differential amplifiers

摘要

The output of a differential amplifier, operating as a comparator, is coupled through a first switch to charge a small valued capacitor C1. The charge in the small capacitor can be coupled through a second switch to charge a larger value capacitor C2. The charge on the larger capacitor creates a voltage thereacross which is C1/(C1+C2) that which was initially across capacitor C1. The voltage across the capacitor C2 is coupled to the negative terminal of the differential amplifier and is lessened in value via a buffer and attenuator circuit. The positive terminal is coupled to ground. The output of the comparator would normally have a polarity based upon the sign of the "offset error" of the comparator less the voltage at the negative terminal.