Semiconductor Components Industries, LLC

Shinya Inaba

Kazunari Kurokawa

Toru Odajima

A noise level of an output signal is maintained low. An adjacent interference detecting unit compares a signal level of a wide band signal which is a desired station signal of a relatively wide band and a signal level of a narrow band signal which is a desired station signal of a relatively narrow band, and judges that adjacent interference has occurred when the signal level of the narrow band signal is less than or equal to a predetermined level even though the signal level of the wide band signal is greater than or equal to a predetermined level. A variable amplifier () attenuates an L&#x2212;R signal and forms a monophonic signal when the signal level of the narrow band signal is lower than a predetermined level. With this process, when there is adjacent interference, a signal level of the narrow band signal at which the attenuating unit starts attenuating the L&#x2212;R signal is changed to a relatively high value.

Stereo signal processing circuit

To adjust a tuning frequency without an output being muted while an oscillation frequency is adjusted. A tuning circuit includes a pair of an inductor and a tuning variable capacitor unit, adjusts a tuning frequency by changing a capacitance of the tuning variable capacitor unit, and obtains a tuning signal having a limited band from a received signal. The tuning circuit includes an oscillating inductor that passes a current corresponding to the tuning signal, an oscillating variable capacitor unit that adjusts the oscillation frequency of a system including the oscillating inductor, and a controller that changes a capacitance of the oscillating variable capacitor unit correspondingly to a desired tuning frequency while adjusting the capacitance such that the oscillation frequency corresponds to the desired tuning frequency, and adjusts a capacitance of the tuning variable capacitor unit in accordance with the adjusted capacitance of the oscillating variable capacitor unit.

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Gunma-ken, Japan

Shinya Inaba