Patent ID: 8072268
Filing Date: 2011-12-06
Classification: H03F

Abstract:
1. An operational amplifier for amplifying a difference between a first input signal and a second input signal, comprising: an input stage for generating branch currents from a first current in proportions responsive to the first input signal and the second input signal; an output stage for generating a first output signal from a second current and giving the output signal a potential responsive to one of the branch currents in the input stage; a first transistor for supplying the first current to the input stage responsive to a first bias potential, the first transistor having a gate terminal for receiving the first bias potential; a second transistor for supplying the second current to the output stage responsive to a second bias potential, the second transistor having a gate terminal for receiving the second bias potential; a first gate line connected to the gate terminal of the first transistor, for supplying the first bias potential to the first transistor; a second gate line connected to the gate terminal of the second transistor, for supplying the second bias potential to the second transistor; a first bias potential generator connected to the first gate line, for generating the first bias potential; and a second bias potential generator connected to the second gate line, for generating the second bias potential wherein the first gate line and the second gate line are electrically isolated from each other, wherein the first bias potential generator comprises an eighth transistor having a gate terminal and a drain terminal both connected to the first gate line and a first current source connected to the drain terminal of the eighth transistor; and wherein the second bias potential generator comprises a ninth transistor having a gate terminal and a drain terminal both connected to the second gate line and a second current source connected to the drain terminal of the ninth transistor.