Patent ID: 6356153
Filing Date: 2002-03-12
Classification: H03F

Abstract:
A method of operating a differential amplifier, comprising:(a) applying an input signal between gates of differentially connected first and second input transistors of a first channel type, and also between gates of differentially connected third and fourth input transistors of the second channel type; (b) applying a signal produced by the first input transistor to a junction between a source of a first cascode transistor of the second channel type and a first resistive element also coupled to a first supply voltage rail; (c) applying a signal produced by the third input transistor to a junction between a source of a second cascode transistor of the first channel type and a second resistive element also coupled to a second supply voltage rail; (d) applying a signal produced between the drain of the first input transistor and a drain of the second input transistor between a first and second inputs of a first gain boost amplifier having an output coupled to the gate of the first cascode transistor, and applying a signal produced between the drain of the third input transistor and a drain of the fourth input transistor between a first and second inputs of a second gain boost amplifier having an output coupled to the gate of the second cascode transistor; and (e) providing an output stage including a pull-up transistor of the second channel type coupled between the first supply voltage rail and the output terminal, a pull-down transistor of the first channel type coupled between the second supply voltage rail and the output terminal, and a class AB bias circuit coupled between drain electrodes of the first and second cascode transistors and the gate electrodes of the pull-up and pull-down transistors.