Qpsk demodulation circuit and qpsk demodulating method

摘要

PROBLEM TO BE SOLVED: To provide a QPSK demodulation circuit and a QPSK demodulation method which allow for phase control with a simple configuration.SOLUTION: A QPSK demodulation circuit and a QPSK demodulation method can be configured simply by monitoring the photocurrent output of a QPSK optical reception signal with a dual pin photodiode, and avoiding equivalence convergence by using the information of the rising state and falling state of the photocurrent output of two photodiodes, and the magnitude of photocurrent outputs of the two photodiodes.