Patent ID: 7782154

Claim:
A modulator, comprising: a loop filter, for calculating a difference between an input signal and an output signal, accumulating the difference, and generating a first signal according to the difference and a reference frequency; a frequency generator, providing a second signal with the reference frequency to the loop filter and comprising: a logic circuit, for receiving a third signal, comparing a level of the third signal with a level of a first reference signal or a second reference signal, and outputting a logic signal; a current array, coupled to the logic circuit and generating the second signal and a dummy signal according to the logic signal, wherein the second signal and the dummy signal are related to each other; and a dummy load, coupled to the current array, the dummy load representing a load circuit of the loop filter, wherein the current array uses the dummy signal to drive the dummy load to provide the third signal to the logic circuit; and a quantizer, coupled to the loop filter for quantizing the first signal into a digital signal and outputting the digital signal to a next stage circuit of the modulator.