| 摘要 |
PURPOSE:To decrease the chip area in case of circuit integration by using a shift register and two storage devices to constitute a digital low pass filter thereby reducing the hardware. CONSTITUTION:An analog signal inputted from an analog input terminal 11 is converted into a 1-bit digital signal having a sampling frequency fS by a delta modulator DM 12. The 1-bit digital signal is processed by a digital low pass filter comprising a shift register 13, a 1st storage device 14, a 2nd storage device 15 and an IIR filter 16 and outputted from a PCM output terminal 17 as a PCM signal having the sampling frequency fS. Thus, the capacity of the entire storage device is effectively utilized.
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