Patent ID: 7242337

Claim:
A band-pass ΔΣ AD modulator comprising: an analog band-pass filter; an AD converter for performing AD conversion using a sampling clock having a predetermined sampling frequency “fs”; and a DA converter for performing DA conversion using the sampling clock having the sampling frequency “fs”, wherein said band-pass ΔΣ AD modulator subtracts an analog signal from said DA converter from an inputted analog signal, outputs an analog signal having a subtraction result to said AD converter via said analog band-pass filter, outputs a digital signal from said AD converter to the DA converter, and outputs the digital signal as a digital signal subjected to a band-pass ΔΣ AD modulation processing, wherein the highest input frequency “fin” of the inputted analog signal is substantially set to three-fourths of the sampling frequency “fs”, and wherein said DA converter converts an inputted digital signal into an analog signal, and outputs the analog signal, which is inverted or not in response to a value of the inputted digital signal and has an amplitude of substantially zero and a gradient of substantially zero at a timing k/(2fs), where “k” is any integer.