| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem that a conventional frequency conversion circuit has caused an adverse effect on the performance of a device employing the frequency conversion circuit due to a temperature change/a secular change in the characteristic of circuit components and due to production of spurious radiation in an output when a high frequency reception signal and a local signal generator output are multiplied to frequency-convert the high frequency into an intermediate frequency signal. SOLUTION: An analog/digital converter 1 uses an output signal fs of a signal generator 3 to sample an input signal fin and to convert the input signal into an output signal fs, a digital/analog converter 2 uses an output signal of the signal generator 3 to convert the output signal of the analog/digital converter 1 into an analog signal again. A BPF 4 selects a desired image component among analog signals being an output of the digital/analog converter 2 that consists of image signals appearing at a half of the sampling frequency fs to obtain an output signal with a frequency fout.
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