| 摘要 |
PURPOSE:To remove an image spurious response so as to remove the necessity if dealing with the intermediate frequency signal having high frequency and to attain a high density package by directly fetching the signal of phase information from a high frequency input signal. CONSTITUTION:The high frequency input signal is detected in terms of phase with a local oscillation signal having the same frequency in a phase information extraction part 102 so as to extract the signal of frequency shift in the input signal. The local oscillation signal having optional frequency is controlled in terms of phase with the extracted signal of frequency shift in a phase control part 104, so that the optional frequency of signal having the same frequency shift as the high frequency input signal is generated and the signal is detected in terms of frequency in a frequency detection part 105 so as to demodulate a sound signal. Though the signal of frequency shift is directly fetched from the high frequency input signal, it is not converted into the intermediate frequency, so that the image spurious response does not occur and problems caused by the image spurious disturbance can be solved.
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