Patent ID: 7215938

Claim:
A radio-frequency (RF) receiver comprising: an input terminal for receiving an RF signal in a first frequency band and an RF signal in a second frequency band lower than the first frequency band; a first tuned filter connected with the input terminal and allowing a signal of a passing frequency in the RF signal in the first frequency band to pass through the first tuned filter; a local oscillator; a frequency divider for frequency-dividing a signal output from the local oscillator; a first mixer operable to mix a signal output from the first tuned filter with the signal output from the local oscillator to convert the signal output from the first tuned filter into a signal of an intermediate frequency; a second tuned filter connected with the input terminal and allowing a signal of a passing frequency of the RF signal in the second frequency band to pass through the second tuned filter; a second mixer operable to mix a signal output from the second tuned filter with a signal output from the frequency divider to convert the signal output from the second tuned filter into a signal of the intermediate frequency; an output terminal for outputting the signals of the intermediate frequency output from the first mixer and the second mixer; and a phase-locked-loop (PLL) circuit operable to control an oscillation frequency of the local oscillator, the passing frequency of the first tuned filter, and the passing frequency of the second tuned filter, wherein the signal output from the frequency divider contains a first output signal and a second output signal different in phase by 90 degrees from the first output signal, the first and second output signal being produced by frequency-dividing the signal output from the local oscillator, wherein the second mixer includes a third mixer operable to mix the signal output from the second tuned filter with the first output signal of the frequency divider, a first phase shifter operable to shift a signal output from the third mixer in phase by 90 degrees, and a fourth mixer operable to mix the signal output from the second tuned filter with the second output signal of the frequency divider, and wherein a signal output from the fourth mixer and a signal output from the first phase shifter are output from the output terminal.