Sanyo Electric Co., Ltd.

Mikio Yamagishi

Kazuhisa Ishiguro

Hirohisa Suzuki

Ryuichi Ogawa

Akira Kabashima

A reactance circuit comprises a differential amplification circuit formed by differentially connecting the first and second transistors to each other, a load connected to a collector of the first transistor, a reactance element interposed between a base of the first transistor and a reference potential point, and a capacitor and a resistor connected in series between the collector and the base of the first transistor. A negative feedback loop to the first transistor is formed by the capacitor and the resistor. Accordingly, when the collector of the first transistor is used as an output terminal, a negative equivalent reactance is produced in the output terminal.

Variable reactance circuit producing negative to positive varying

A diversity receiver includes first and second antennae for receiving an RF signal, and an antenna switching circuit for selecting one of the first and second antennae. A first detection circuit having a high sensitivity, and a second detection circuit having a low sensitivity are provided, each detecting a noise signal contained within the received RF signal in different sensitivity. A field strength detection circuit is provided for detecting a field strength of the received RF signal, and a selection circuit is provided for selecting either one of the first and second detection circuits according to the output signal of the field strength detection circuit, and for providing a switching signal to the antenna switching circuit. Thus, when the field strength is relatively strong, the first detection circuit with high sensitivity is used for the noise detection, and when the field strength is relatively weak, the second detection circuit with low sensitivity is used for the noise detection.

Diversity receiver

Levels of a stereo sum signal and a stereo difference signal are detected by first and second level detectors (7, 9), respectively. Outputs of the first and second level detectors (7, 9) are compared with each other by a comparator (10). A voltage controlled amplifier (4) is responsive to an output of the comparator (10) for changing a level of the stereo difference signal, when a broadcasting signal including only either one of a left stereo signal and a right stereo signal is received, such that the levels of the stereo sums signal and the stereo difference signal are equal to each other.

Fm stereo demodulator

A stereo demodulator of a matrix system comprises: a first amplifier (23, 24, 25) for negative feedback amplification of a stereophonic composite signal, a first voltage-current converter (26) for detecting a current-form stereophonic sum signal responsive to a voltage output of the first amplifier, a non-inversion amplifier (27) for negative feedback non-inversion amplification of the stereophonic composite signal, an inversion amplifier (28) for negative feedback inversion amplification of the stereophonic composite signal, a second voltage-current converter (29, 38) for outputting a first current-form stereophonic subchannel signal responsive to a voltage output of the non-inversion amplifier (27), a third voltage-current converter (30, 39) for supplying a current-form signal stereophonic subchannel signal responsive to a voltage output from the inversion amplifier (28), a difference signal demodulator (31) for providing stereophonic difference signals of opposite phases in the form of current signals from the outputs of the second and third voltage-current converters, and an matrix circuit (41) for performing matrix processing on the received stereophonic sum signal from the first voltage-current converter and the stereophonic difference signals from the difference signal demodulator (31) and outputting right and left stereophonic signals in a voltage signal form.

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Gunma, Japan

Mikio Yamagishi