Patent ID: 6281753
Filing Date: 2001-08-28
Classification: H03F

Abstract:
A circuit, comprising:a first rail for receiving a first supply voltage;a second rail for receiving a second supply voltage;a differential amplifier circuit coupled to the first rail and the second rail and having a differential input for receiving a common-mode input voltage, the differential amplifier circuit including a differential pair of transistors;a bias circuit coupled to said differential amplifier circuit for applying a bias voltage to the differential pair of transistors, the bias circuit controlling the threshold voltage of the differential pair of transistors in the response to the common-mode input voltage to turn the differential pair of transistors on when the common-mode input voltage is in a range extending from the first supply voltage to the second supply voltage wherein the bias circuit provides a first bias voltage to turn the differential pair of transistors on when the common mode input voltage is in a first range extending from the first supply voltage to a first threshold voltage and a second bias voltage to turn the differential pair of transistors on when the common mode input voltage is in the second range extending from second supply voltage to the first threshold voltage.