Transconductance amplifier based on self-biased cascode structure

Abstract

Provided in the present invention is a transconductance amplifier based on a self-biased cascode structure. The transconductance amplifier includes a self-biased cascode input-stage structure constituted by PMOS (P-channel Metal Oxide Semiconductor) input transistors M, M, Mand M, a self-biased cascode first-stage load structure constituted by NMOS (N-channel Metal Oxide Semiconductor) transistors M, M, Mand M, a second-stage common-source amplifier structure constituted by an NMOS transistor Mand a PMOS transistor M, a bias circuit structure constituted by NMOS transistors Mand Mand a PMOS transistor M, an amplifier compensation capacitor C, an amplifier load capacitor C, a reference current source Iref and a PMOS transistor Mthat provides a constant current source function. Further provided in the present invention is a transconductance amplifier based on a self-biased cascode structure, which adopts an NMOS transistor as an input transistor. Both input transistors and load transistors of a first-stage amplifier of the present invention adopt self-biased cascode structures, such that the output impedance and the DC gain of the first-stage amplifier are increased. Substrate voltages of the MOS transistors of the first-stage amplifier are provided by an amplifier bias circuit. Owing to a connection mode of the compensation capacitor C, a higher figure of merit is achieved.