Sanyo Electric Co., Ltd.

Sanyo Semiconductor Co., Ltd.

Jun Suzuki

Masaki Kinoshita

Takao Saeki

Hiroya Yamamoto

Takashi Iijima

An FM receiver that is suitable for reducing a transmission bandwidth Wof a bandpass filter to remove adjacent-channel interference, and increasing Wto prevent audio distortion. A detection output signal Sis inputted to an HPFwhen a reception electric field strength signal Sindicates an intermediate or stronger electric field. In a weak electric field, an AC component signal S, which is extracted from an intermediate signal Sprior to detection and which has fewer high-pass noise components than S, is inputted to the HPF. A control circuitdetects a case as an adjacent-channel interference state when a large amount of high-pass components passes through the HPF, and reduces Wof an IFBPFin order to remove adjacent-channel interference. When a small amount of high-pass components is transmitted, Wis increased in order to minimize audio distortion.

FM receiver

A noise canceller that a receiving signal received by a receiving antenna is input to, the noise canceller removing a pulse noise superimposed on the receiving signal to output the signal, the noise canceller comprising: a pulse noise detecting unit that detects the pulse noise superimposed on the receiving signal; a reception level detecting unit that detects the level of the receiving signal; a level hold unit that is triggered by the detection of the pulse noise with the pulse noise detecting unit to hold the level of the receiving signal in a process on the preceding stage of the output; and a level hold period setting unit that sets the level hold period when the level is held in the level hold unit in accordance with the level of the receiving signal detected by the reception level detecting unit.

Noise canceller and AM receiving apparatus using the same

Transistors ( ) turn on and off with mutually opposite phase input signals. Capacitors ( ) discharge when the transistors ( ) turn on, and capacitors ( ) are charged by constant current from constant current sources ( ) when the transistors ( ) turn off. As a result, a gradually rising voltage is obtained at the positive input ends of comparators ( ) while the input signals are L. By comparing this with fixed voltages of reference sources ( ), signals having rise timing shifted from input signals by 90&deg; are obtained. The outputs of the comparators ( ) are mutually shifted by 180&deg;, and at the rise of these outputs, an RS flip-flop ( ) is set and reset so that signals delayed in phase by 90&deg; with respect to the input signals are obtained at its outputs.

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Kumagaya, Japan

Jun Suzuki