The MM74C932 MM54C932 consists of two independent output phase comparator circuits The two phase comparators have a common signal input and a common comparator input The signal input can be directly coupled for a large voltage signal or capacitively coupled to the self-biasing amplifier at the signal input for a small voltage signal Phase comparator I an exclusive-OR gate provides a digital error signal (phase comp I out) and maintains 90 phase shifts at the VCO center frequency Between signal input and comparator input (both at 50% duty cycle) it may lock onto the signal input frequencies that are close to harmonics of the VCO center frequency