Phase sensitive detector described here has two principal applications:
A- To produce a d.c out put proportional to- the amplitude of an incoming a,c signal
and indicate, by the outut Polarity, the phase of the signal with respect to an internal reference.
B- To detect the presence of a signal of known phase and frequency which would
otherwise be lost in «background noise» and to measure its amplitude.
This phase sensitive detector has high linearity over an inpu- range of 10 : 1:up to 100
KHz. and besides having a quick response consistent with good rejcetion of quadrature component
and interfering frequencies, has excellent long term stability.
This circuit could also be used as a modulator
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