Patent ID: 6950694
Filing Date: 2005-09-27
Classification: A61B

Abstract:
1. An apparatus for sensing a difference between first and second input voltages, the apparatus comprising: a reference circuit, where the reference circuit includes an input receiving an amplified signal based on first input voltage, and an output providing a reference voltage; a compensation circuit, where the compensation circuit includes an input receiving an amplified signal based on the second input voltage, and an output providing a compensated voltage based on reference voltage; a first amplification circuit, where the first amplification circuit includes a first input receiving a signal based on the reference voltage, a second input receiving a signal based on the compensated voltage, and an output providing a differential output signal based on a difference between the signals of the first and second inputs of the first amplification circuit; an averager circuit, where the averager circuit includes a first input receiving a signal based on the reference voltage, a second input receiving a signal based on the compensated voltage, and an output providing a common mode (CM) output signal based on the signals at the first and second inputs of the averager circuit; and an impedance circuit means for adjusting an impedance of the compensation circuit, based on the signals received from the outputs of the first amplification circuit and the averager circuit for reducing an impact of the CM output signal on the output of the first amplification circuit.