Offset independent active RC filters

Hilberman's theorem is used as a guide to develop second order single op-amp active RC filters in which the output voltages are free from offsets arising from the use of active elements. These filters are useful in instrumentation applications in which the average value of the input signal must be carefully preserved or entirely eliminated with no contamination from offset voltages. The dynamic ranges, sensitivities, and the effects of op-amp finite gain bandwidth product are determined for each filter. It is shown that the order of these filters can be increased for the highpass and bandpass circuits while retaining the desirable features.< >