Phase detector

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A phase detector or phase comparator is a circuit that compares the phases of an oscillation with a reference oscillation defined in the phase and outputs the phase difference as a signal in the case of phase modulation . A phase detector is also required in the phase-locked loop circuit.

Phase comparators can be analog or digital. Digital phase comparators are e.g. B. XOR gate . A pulse voltage is generated at the output, the pulse duty factor and thus the arithmetic mean value change with the phase shift of the two input voltages Ux and Us.

Schematic diagram of a phase detector with 2 flip-flops and AND gate

Phase detectors can also be implemented with flip-flops (see principle diagram). The advantage over the solution with the XOR gate is that, due to the two outputs (P and N), it is also possible to tell whose edge switched the flip-flop first.

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