FREQUENCY COMPARISON CIRCUIT, FREQUENCY CONTROL CIRCUIT, METHOD FOR CONTROLLING FREQUENCY COMPARISON CIRCUIT, AND RADIO TRANSMITTER-RECEIVER

摘要

PPROBLEM TO BE SOLVED: To improve the safety and convenience of a radio transmitter-receiver by reducing the power consumption of the radio transmitter-receiver. PSOLUTION: This frequency comparison circuit includes: an in-phase baseband signal extracting means for mixing an input signal with a local signal, and extracting an in-phase baseband signal having a differential frequency being a difference between the frequency of the input signal and the frequency of the local signal from the obtained signal; an orthogonal baseband signal extracting means for mixing the input signal with an orthogonal local signal being a signal obtained by shifting the phase of the local signal only by a prescribed value, and extracting an orthogonal baseband signal having the differential frequency from the obtained frequency; a polarity determining means for determining the polarity of the differential frequency from a polarity relation between the in-phase baseband signal and the orthogonal baseband signal; and an absolute value acquiring means for acquiring an absolute value of the differential frequency from a period of the in-phase baseband signal or the orthogonal baseband signal. PCOPYRIGHT: (C)2011,JPO&INPIT