PURPOSE: To eliminate the need for a phase detection circuit and to simply constitute a PM wave modulation circuit by outputting a Manchester modulation signal from a comparator and a flip-flop.

CONSTITUTION: First and 2nd comparators A2, A3 compare positive and negative PM wave inputs (a) based on positive and negative reference voltages VT1, VT2 respectively to obtain outputs b, c, which set/reset a flip-flop F1, then an output (d) is obtained. Thus, the digital signal output (d) is a Manchester modulation output and a demodulation digital signal is obtained by using a timing extraction circuit D1 and an identification circuit A6. Thus, the PM wave demodulation circuit with simple constitution not requiring a phase detection circuit is realized.