Patent ID: 7782137
Filing Date: 2010-08-24
Classification: H03F

Abstract:
1. A differential circuit with a function to cancel an input offset voltage of said differential circuit, comprising: a primary amplifier with a differential configuration having a pair of inputs and a pair of outputs; and an offset canceller including, a buffer amplifier with a differential configuration having a pair of inputs and a pair of outputs, said buffer amplifier inversely coupling said outputs of said primary amplifier with said inputs of said primary amplifier, and a low-pass filter coupled between said outputs of said primary amplifier and said inputs of said buffer amplifier, said low-pass filter including a filtering resistor and a capacitor unit, said filtering resistor connected between said output of said primary amplifier and said input of said buffer amplifier, said capacitance unit including a Miller amplifier with a closed loop gain and a capacitor connected between output and input of said Miller amplifier, wherein said closed loop gain of said Miller amplifier is independent of an input level of said Miller amplifier.