ADAPTIVE COMMON MODE BIAS FOR DIFFERENTIAL AMPLIFIER INPUT CIRCUITS

摘要

PURPOSE: An adaptive common mode bias for differential amplifier input circuits is provided to improve the DC gain accuracy of a differential amplifier by biasing input devices and current source devices in an ideal position. CONSTITUTION: A differential signal(100) is received by a common mode detection circuit(102) and a differential amplifier(110). The common mode detection circuit monitors the differential signal for determining a common mode voltage(104) of the differential signal. The common mode voltage passes through a common mode inversion circuit(106) which generates a body voltage(108). The body voltage has an inversion relation with a common mode voltage. A differential amplifier generates an output signal(114). A circuit system(116) is comprised of the common mode detection circuit, the common mode inversion circuit, and the differential amplifier.