| 摘要 |
PROBLEM TO BE SOLVED: To provide a demodulating circuit suppressing an increase in current consumption even when the Fs of input digital data becomes high. SOLUTION: A digital data demodulating circuit 100 is equipped with: a digital data input terminal 101; a stopping-range attenuation-quantity control signal terminal 102; a stopping-range attenuation-quantity variable digital filter 103 which is variable in stopping-range attenuation quantity according to the Fs of digital data to be inputted; a digital-to-analog converter 104 which converts digital output into an analog signal; and a low-pass filter 105 which removes a return noise component from the output of the digital-to-analog converter 104. The circuit makes control to decrease the stopping-range attenuation quantity of the stopping-range attenuation-quantity variable digital filter 103 with a stopping-range attenuation-quantity control signal when the Fs of the input digital data is outside the audible band (e.g. Fs/2≥about 20 kHz). COPYRIGHT: (C)2007,JPO&INPIT
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