Abstract: A phase locked loop circuit for synchronizing with carrier wave includes: a variable divider for generating a first reference signal and a second reference signal whose frequency is same as the frequency of the first reference signal and whose phase is shifted by 90 degrees with respect to the phase of the first reference signal, the variable divider varying the frequencies of the first reference signal and the second reference signal in accordance with a control signal; a first multiplier for multiplying an input signal by the first reference signal; an exclusive OR circuit for operating an exclusive OR of the input signal and the output signal of the first multiplier; a phase comparator for receiving the first reference signal, the second reference signal and the output signal of the exclusive OR circuit, and detecting a value and a direction of a phase difference between the input signal and the first reference signal to produce phase comparison signal including series of clock pulses whose number correspo

Abstract: A bi-phase shift keying signal demodulation circuit for an RDS receiver receives RDS modulation signal and reproduces RDS data from the RDS modulation signal. The RDS modulation signal is produced by modulating a sub-carrier by a signal modulated by a bi-phase shift keying modulation using the RDS data.

Abstract: A radio receiver is disclosed having a wide filter and a narrow filter, each of which is connected with the front end and outputs an intermediate frequency signal. To the output of the filters are connected first and second detectors, respectively. A subtracter receives the outputs of the detectors and subtracts one from the other. A switch receives the output of the subtracter and directs the outputs of detectors in such a way that the switch is switched to a first position for directing the demodulated output from the first detector to a following circuit when the difference is below a reference level, and to a second position for directing the demodulated output from the second detector to the following circuit when the difference is above the reference level.