Patent ID: 7609187

Claim:
A ΔΣ modulator comprising: an oscillator changing a frequency thereof according to an analog signal to be converted into a digital signal, wherein the analog signal is input into the oscillator, and the oscillator outputs a frequency modulation signal whose frequency changes according to the voltage of the analog signal; a reference signal source outputting a reference signal at a predetermined frequency; a mixer mixing the frequency modulation signal output from the oscillator and the reference signal output from the reference signal source; a low-pass filter passing a low frequency component of the frequency modulation signal output from the mixer; a quantizing unit quantizing the frequency modulation signal output from the low-pass filter; and an operation circuit applying a predetermined operation to a digital signal output from the quantizing unit, wherein a center oscillation frequency of the oscillator is set higher than a target center oscillation frequency of the frequency modulation signal output from the low-pass filter.