| 摘要 |
PURPOSE:To simplify the circuit constitution of a signal converting circuit and to improve the characteristic of the circuit, by performing frequency conversion to a lower frequency band by making the difference between a carrier frequency and sampling frequency into a carrier frequency and, simultaneously, performing analog/digital (AD) conversion. CONSTITUTION:An oscillator circuit 11 which inputs band signals having its spectrum concentrated to the vicinity of a carrier frequency has the oscillating frequency in the vicinity of carrier frequency and A/D converter 10 which samples the band signals of analog signals with the output signal of the oscillator circuit 11, are provided. Then frequency is converted to a lower frequency band whose carrier frequency is the difference between the carrier frequency and a sampling frequency and simultaneously A/D conversion is carried out. Therefore, a means for converting band signals to a lower frequency band is eliminated and the circuit constitution of this signal converting circuit can be simplified. Moreover, the characteristic of this circuit is improved.
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