Patent ID: 6178315
Filing Date: 2001-01-23
Classification: H03J,H04B

Abstract:
An FM radio receiver comprising:a radio frequency tuning circuit for selecting a frequency modulated signal from an antenna; anda local oscillator tuning circuit for tuning to an oscillating signal so as to convert said frequency modulated signal to an intermediate frequency;wherein said radio frequency tuning circuit and said local oscillator tuning circuit each have variable capacitance diode elements;wherein said variable capacitance diode elements of said radio frequency tuning circuit and said variable capacitance diode elements of said local oscillator tuning circuit are connected to a tuning control voltage source;wherein said radio frequency tuning circuit has a capacitance variable ratio set so as to be capable of receiving continuously a first receiving band and a second receiving band; andwherein said local oscillator tuning circuit is so constructed that an inductance value and a capacitance variable ratio can be switched according to a selected one of said first or second receiving band, so that said local oscillator tuning circuit is set to lower heterodyne when said first receiving band is selected or to upper heterodyne when said second receiving band is selected.