| 摘要 |
In the high-frequency receiving device, a frequency dividing circuit of x1/N divides a sampling clock signal of both A/D converters by the dividing ratio based on a controlling signal outputted from a controlling signal generator, and generates a constant current reference signal whose frequency is equal to a cut-off frequency of a low-pass filter which is to be set. Based on the constant current reference signal, a phase shift circuit, a mixer, a low-pass filter, a DC amplification circuit, and a constant current source perform loop back control so that an output of the mixer is 0, and input an output signal of the DC amplifying circuit as the output signal of a controlling circuit to a constant current source. Thus, the constant current source does not adjust the scale factor, so that a current according to the cut-off frequency which is to be set is inputted to the low-pass filter. As a result, it is possible to provide a filter-provided device in which a frequency value indicative of a passing frequency characteristic can be set so accurately.
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