Patent ID: 6946905
Filing Date: 2005-09-20
Classification: G09G,H03F

Abstract:
1. An offset cancel circuit for a voltage follower to cancel an offset voltage of the voltage follower, the voltage follower including a differential amplifying circuit having a current mirror circuit as a load and an output buffer circuit subsequent to the differential amplifying circuit, the current mirror circuit having first and second current ends, the offset cancel circuit comprising: a differential input circuit including first and second transistors, the first transistor having a current-path whose one end is connected to the first current end and having a gate, the second transistor having a current-path whose one end is connected to the second current end and having a gate receiving a reference potential; a first switch connected between an inverting input and a non-inverting input of the differential amplifying circuit; a second switch connected between the inverting input and an output of the output buffer circuit, the second switch being on/off-controlled adversely to the first switch; a third switch connected between the output of the output buffer circuit and the gate of the first transistor, the third switch being on/off-controlled similarly to the first switch; and a capacitor connected between the gate of the first transistor and a predetermined potential.