Apparatus for detecting DC content of an AC waveform

摘要

A circuit for monitoring the DC content of an AC waveform includes a differential amplifier having one input connected to the AC waveform and the other input connected to a capacitive-coupled network that eliminates any DC component in the AC waveform at the frequency being monitored. Additional circuitry is required to cancel any phase shift and reactance of the coupling capacitor. The output of the differential amplifier is a signal which represents the amplitude and polarity of the DC content.