Patent ID: 8131243

Claim:
A receiving circuit comprising: an antenna circuit for receiving an electromagnetic wave to obtain an electric signal; an amplifying unit for amplifying the electric signal obtained by the antenna circuit; a frequency converter/detector unit for converting a frequency of the electric signal amplified by the amplifying unit to obtain an intermediate frequency signal, and for detecting the intermediate frequency signal, thereby outputting a demodulated signal; and a filtering unit for removing an intermediate frequency component from the demodulated signal output from the frequency converter/detector unit, wherein the frequency converter/detector unit comprises: a local oscillator for generating an oscillation signal; plural mixers for mixing the signal amplified by the amplifying unit with the oscillation signal from the local oscillator to generate a first intermediate frequency signal and a second intermediate frequency signal, wherein the first intermediate frequency signal and second intermediate frequency signal are shifted in phase from each other by 90 degrees; and a signal generating synthesizing unit for generating other intermediate frequency signals based on the first intermediate frequency signal and the second intermediate frequency signal, wherein said other intermediate frequency signals are shifted in phase from the first intermediate frequency signal and the second intermediate frequency signal, and for detecting the first intermediate frequency signal, the second intermediate frequency signal and said other intermediate frequency signals and adding the detected signals together, thereby generating a synthesized signal, wherein the signal generating/synthesizing unit reverses the first intermediate frequency signal and second intermediate frequency signal output from the mixers and outputs the reversed first intermediate frequency signal and the reversed second intermediate frequency signal as first other intermediate frequency signals, and generates signals and outputs the generated signals as second other intermediate frequency signals, and wherein said second other intermediate frequency signals have a phase equivalent to a phase difference between the first intermediate frequency signal and the second intermediate frequency signal, a phase equivalent to a phase difference between the second intermediate frequency signal and the reversed first intermediate frequency signal, a phase equivalent to a phase difference between the reversed first intermediate frequency signal and the reversed second intermediate frequency signal, and a phase equivalent to a phase difference between the reversed second intermediate frequency signal and the first intermediate frequency signal, respectively.