| 摘要 |
PROBLEM TO BE SOLVED: To provide a decimation bandpass filter which outputs signals having high bit accuracy to an AGC circuit and has a simple constitution, without increasing the hardware scale and electric current of the filter by decimating the output of a bandpassΔΣAD converter which has an AGC function and enabling the converter to make accurate AGC control. SOLUTION: A bandpassΔΣAD converter 1 converts inputted IF signals into digital signals. A decimation bandpass filter 2 decimates the output of the AD converter 1 so that a 1:4 relation is established between the frequency of the inputted signals and a sampling frequency by means of the input section of an orthogonal detector 4. A bandpass filter 8 outputs the output signal of the decimation bandpass filter 2 to an AGC circuit 3 by limiting the band of the signals. Since the bandpass filter 8 can be constituted without the use of multipliers, etc., the filter 8 can be realized with a simple constitution without increasing the hardware scale and electric current of the filter 8.
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