Patent ID: 6021322
Filing Date: 2000-02-01
Classification: H03J

Abstract:
An AM radio receiver comprising a radio-frequency tuning circuit for selecting amplitude-modulated signal received at antenna; a local oscillator circuit for generating an oscillating signal which is used in a first frequency conversion section to convert receiving signal to an intermediate frequency signal having a higher frequency than that of the receiving signal, wherein:said radio-frequency tuning circuit comprises a tuning coil, and variable capacitance diode elements connected to said tuning coil;said local oscillator circuit comprises an oscillator coil, a variable capacitance diode element connected in parallel with said oscillator coil, and a capacitance element connected in series with said oscillator coil; andthe variable capacitance diode elements of said radio-frequency tuning circuit are connected to a variable voltage source, and the variable capacitance diode element of said local oscillator circuit is connected to the variable voltage source through a voltage adjustment circuit connected to a reference voltage source.