Silicon Laboratories Inc.
Demodulator/detector for digital isolators

Abstract:

A receiver signal path includes a high pass filter that centers a received differential pair of signals around a common mode voltage to generate a centered received differential pair of signals. The receiver signal path includes a demodulator that removes a carrier signal from the centered received differential pair of signals to generate a demodulated signal and generates a logic signal based on the demodulated signal and a predetermined threshold signal. The demodulator includes a differential stage including an extremum selector circuit that generates the demodulated signal based on the centered received differential pair of signals. The demodulated signal corresponds to a mean level of the rectified version of the centered received differential pair of signals. The differential stage includes a second circuit that provides the reference signal based on the predetermined threshold signal. The logic signal is based on a comparison of the demodulated signal to the reference signal.