Patent ID: 7605646
Filing Date: 2009-10-20
Classification: H03F

Abstract:
1. Instrumentation amplifier circuitry comprising: first and second input amplifiers each having a first input, a second input, and an output, a chopped voltage reference circuit producing alternating first and second reference voltage levels on first and second terminals thereof; first and second auto-zero stages, first, second, third and fourth input switches, and first, second, third and fourth output switches in the first input amplifier; third and fourth auto-zero stages, fifth, sixth, seventh and eighth input switches, and fifth, sixth, seventh and eighth output switches in the second input amplifier; and a control circuit for generating various control signals to control the chopped voltage reference circuit, various input switches, and various output switches; wherein the control circuit operates the various input switches and the various output switches during first, second, third and fourth phases so as to auto-zero the first auto-zero stage to the first voltage level during the first phase, auto-zero the third auto-zero stage to the second voltage level during the second phase, auto-zero the second auto-zero stage to the first voltage level during the third phase, and auto-zero the fourth auto-zero stage to the second voltage level during the fourth phase.