Abstract: An FSK radio receiver of direct conversion type, which derives baseband in-phase and phase quadrature signals from a received FSK RF signal in respective mixers by applying local oscillator signals to the mixers differing in phase by 90.degree., in which wide-band baseband 90.degree. phase shifting circuits formed of only digital logic elements phase shift the in-phase and phase quadrature signals to enable a demodulated digital data signal to be obtained by subsequent digital processing. In that processing, signals having a frequency that is double that of the in-phase and phase quadrature signals are derived and used to derive the demodulated data signal, ensuring high accuracy of detection and lowering the accuracy required for the local oscillator frequency.

Abstract: A data receiver includes first and second mixers mixing an input RF signal and a local oscillator signal and generating first and second quadrature baseband-frequency output signals. A phase shifter shifts a phase of the first baseband-frequency output signal by 90 degrees. A third mixer mixes an output signal from the phase shifter and the first baseband-frequency output signal. A fourth mixer mixes the first and second baseband-frequency output signals. A demodulator performs data demodulation by use of output signals from the third and fourth mixers.

Abstract: A frequency synthesizer for use in a high-frequency multichannel radio apparatus and so on. More particularly, a phase-locked loop (PLL) type frequency synthesizer which can perform a pulling process at high speed. Namely, a frequency synthesizer of the present invention can effect a pulling process at high speed by putting input signals to a phase comparator into a state in which the input signals are in phase with each other in an intermittent operation mode and can have strong resistance to noises by providing a 1-bit data latch and gate circuits in a data inputting portion thereof and synthesizing strobe signals at the time of inputting data thereto.

Abstract: A first oscillator outputs a signal having a reference frequency. A first frequency divider divides the frequency of the output signal from the first oscillator. A second oscillator outputs a signal having a target frequency. A second frequency divider divides the frequency of the output signal from the second oscillator. A phase comparator compares phases of output signals from the first and second frequency dividers. An integrator integrates an output signal from the phase comparator and controls the second oscillator in accordance with the integration of the output signal from the phase comparator. A first gate is connected between the first oscillator and the first frequency divider. A second gate is connected between the second oscillator and the second frequency divider. A third gate is connected between the phase comparator and the integrator.

Abstract: A resonator for microwave or VHF-UHF bands has a ring dielectric plate, one surface of which is metalized to make a resonant line, and at least one of other surfaces of which is also metalized to make a grounded or earth conductor. The resonator is very small in size and has a large unloaded Q value. Several embodiments are disclosed.

Abstract: A high frequency oscillator comprising a ring type inductive resonator of a microstrip line constituted in a rectangular or annular loop. Capacitors are serially connected to both ends of the line, thereby improving the low-noise, separation and stability characteristics by use of the steep-phase characteristic of the ring-shaped resonator.

Abstract: Disclosed is a double converter tuner having an input circuit for performing first band control with respect to an input signal, amplifying a band-controlled input signal after automatic gain control is performed, and further performing second band control of a gain-controlled signal, a first IF (intermediate frequency) converter for converting an output generated from the input circuit to a first IF signal having a higher bandwidth than the reception bandwidth of the input signal, a first IF circuit for amplifying an output from the first IF converter, performing third band control and performing a further amplification, a second IF converter for converting an output generated from the first IF circuit to a second IF signal, and a second IF circuit for amplifying an output from the second IF converter, performing fourth band control, and performing another amplification. The first and second IF converters are arranged on different circuit boards to prevent frequency interference therebetween.

Abstract: A wide band analog frequency divider circuit operable at a high frequency in the GHz band, and a frequency synthesizer utilizing the analog frequency divider circuit. The analog frequency divider circuit comprises an LC series circuit having a capacitor and an inductor connected between the anode and the cathode of a diode, and means for applying a forward bias to the diode. The input signal is supplied from the anode side of the diode, and the output is delivered from the cathode side, or the anode side of the cathode is grounded. The frequency synthesizer is arranged to frequency divide the output of a VCO by the analog frequency divider circuit, and to supply the frequency-divided output to a prescaler. The output of the prescaler is further frequency divided by a programmable divider, and the phase difference between the output of the programmable divider and a reference signal is detected thereby to control the oscillation frequency of the VCO.

Abstract: A compact or miniaturized well-shielded double superheterodyne tuner is provided, wherein an input circuit portion, a first mixing portion, a first intermediate frequency bandpass filter, a second mixing portion and an output circuit portion are mounted in separated casings. The first mixing portion and the second mixing portion are provided on printed boards and each mounted on a bottom plate of the casing. The casings containing the first and second mixing portion are arranged in a manner such that grounded surfaces of the printed boards contained in the casings are arranged face to face. The casing containing the bandpass filter is contacted adjacently to a common face of the face to face casings. Each of the casings containing the input and output circuit portions is located adjacently to each of faces common to the face to face casings and the filter containing casing. Some structual improvements are also provided for simplifying the manufacture and adjustment of the tuner.

Abstract: A wide band analog frequency divider circuit operable at a high frequency in the GHz band. The analog frequency divider circuit comprises an LC series circuit having a capacitor and an inductor connected between the anode and the cathode of a diode, and means for applying a forward bias to the diode. The input signal is supplied from the anode side of the diode, and the output is delivered from the cathode side, or the anode side if the cathode is grounded.