Patent ID: 7144494

Claim:
A circuit arrangement for compensating interference signals in the control loop of a linear lambda probe comprising: an evaluation circuit with a differential amplifier which forms the difference between a Nernst voltage which is subjected to an interference signal and a reference voltage, a controller generating a controlling voltage from the difference wherein the controlling voltage is converted into a pumping current by a subsequent pumping current source said pumping current being fed back to said linear lambda probe, a compensation circuit, coupled between the output of the differential amplifier and the input of the controller, for generating a compensation signal which is approximated in its curve profile to the interference signal and has an amplitude and frequency which are identical to the interference signal but phase-shifted through 180°, and for subtracting the compensation signal from the differential signal, wherein the compensation circuit comprises an amplifier which is connected as a buffer and an integrator, the differential signal and the output signal of the integrator are fed to the input of the buffer amplifier, and wherein the output signal of the buffer amplifier is fed to the inverting input of the integrator and to the input of the controller.