MOSFET single-pair differential amplifier having an adaptive biasing scheme for rail-to-rail input capability

摘要

A single pair differential amplifier circuit (90) provides signal amplification across the full amplifier power-supply voltage range. The differential amplifier circuit (90) is coupled to the first rail (122) and the second rail (124) and has a differential input (114 and 116) for receiving a common-mode input voltage. A bias circuit (126) is coupled to the differential amplifier circuit (90) for applying a bias voltage to the differential pair of transistors (102 and 104) such that the bias circuit (126) controls the threshold voltage of the differential pair of transistors (102 and 104) in the response to the common-mode input voltage. The bias circuit (126) turns differential pair of transistors (102 and 104) on when the common-mode input voltage is in a range extending from the first supply voltage to the second supply voltage.