Patent ID: 9628035
Date: 2017-04-18
CPC Classifications: H03F

Claim:
1. An operational amplifier circuit, comprising: a first stage amplifier circuit, coupled to a first input node for receiving a first input signal and amplifying the first input signal to generate a first amplified signal; a second stage amplifier circuit, coupled to the first stage amplifier circuit for receiving the first amplified signal and amplifying the first amplified signal to generate a first output signal at a first output node; and a first feedforward circuit, directly connected to the first input node and a gate of a transistor comprised in the second stage amplifier circuit for feeding the first input signal forward to the second stage amplifier circuit, wherein the second stage amplifier circuit comprises a first circuit subunit for receiving the first amplified signal and amplifying the first amplified signal, and the first circuit subunit comprises: a first transistor, coupled between an operating voltage and the first output node; and a second transistor, coupled between the first output node and a ground, wherein the first input signal is fed to at least one of a gate of the first transistor and a gate of the second transistor, and wherein the first stage amplifier circuit is further coupled to a second input node for receiving a second input signal and amplifying the second input signal to generate a second amplified signal, the second stage amplifier circuit further receives the second amplified signal and amplifies the second amplified signal to generate a second output signal at a second output node, and wherein the first input signal and the second input signal are a pair of differential input signals and the first output signal and the second output signal are a pair of differential output signals.