Patent ID: 7084700
Filing Date: 2006-08-01
Classification: H03F

Abstract:
1. A differential voltage amplifier circuit provided with a first differential amplifier, comprising: a first switch section which short-circuits between input paths corresponding to a first input path from a first input terminal to the first differential amplifier and a second input path from a second input terminal to the first differential amplifier; a voltage holder which holds a short-circuit output voltage outputted from the first differential amplifier upon a short-circuit between the input paths; a second switch section which connects an output terminal of the first differential amplifier and the voltage holder upon holding the short-circuit output voltage; a subtraction circuit section which subtracts the short-circuit output voltage held in the voltage holder from a first reference voltage; and a third switch section which supplies the first reference voltage to a bias voltage terminal for setting a bias point of an input voltage of the first differential amplifier upon the short-circuit between the input paths and supplies an output of the subtraction circuit section as a second reference voltage upon differential voltage amplification.