Finnegan, Henderson, Farabow, Garrett & Dunner
Tuning detector
 This present invention relates to a tuning detector used for an FM receiver, and it has a mute band detecting function to solve a problem in relation to setting of a ratio of a tuning detection band to a non-mute band. For this reason, a resistor for setting a band to be detected is connected between one terminal of a capacitor for removing an AC signal included in an FM detection signal and one terminal of the power source for applying a reference voltage. The input terminal of a first buffer circuit is connected to the connection point of the resistor and the capacitor, and the second buffer circuit is connected to the connection point of the power source and the resistor. A tuning band detecting section for detecting a tuning band is connected to the output terminals of the first and second buffer circuits. A detuning mute band detecting section for detecting a detuning mute band is connected between an arbitrary dividing point of the resistor and the above one terminal of the power source. The mute circuit controls the gain of the amplifier for amplifying an FM detection signal in response to an output signal from the detuning mute band detecting section. 
Kabushiki Kaisha Toshiba
H H
H03G H03J
inventional inventional
Shuji Masashi
Watanabe Itoh