Patent ID: 8742848
Filing Date: 2014-06-03
Classification: H03F

Abstract:
1. A method for improving common mode rejection in an instrumentation amplifier, the instrumentation amplifier having an input section comprising a first input amplifier receiving a first input signal at a first input terminal, and a second input amplifier receiving a second input signal at a second input terminal, the input section outputting common mode and differential signals, the method comprising: providing a trimmable first capacitor in the first input amplifier and a trimmable second capacitor in the second input amplifier, the trimmable first capacitor and trimmable second capacitor being in respective feedback loops and controlling respective frequency responses of the first input amplifier and second input amplifier; applying a common mode AC signal to the first input terminal and the second input terminal; and measuring signals in the instrumentation amplifier while trimming at least one of the first capacitor and second capacitor to obtain substantially equal common mode signals at outputs of the first input amplifier and the second input amplifier.