Patent ID: 7696914

Claim:
A sigma delta modulator, comprising: a loop filter, for filtering a summed signal to generate a filtered signal; a single bit quantizer, coupled to the loop filter, for performing a quantization process to the filtered signal to generate a quantized signal; a single bit adjustable DAC, coupled to the single bit quantizer, including an adjustable configuration, for generating a feedback signal according to the quantized signal and the configuration; and an adder, coupled to the loop filter and the single bit adjustable DAC, for summing an input signal and the feedback signal to generate the summed signal; wherein the single bit adjustable DAC includes a first configuration setting circuit which comprises: a resistor; a first switch, coupled to the resistor; a second switch, coupled to the first switch and a first voltage; a third switch, coupled to the first switch and a common voltage; and a fourth switch, coupled to the resistor and a second voltage; wherein the first switch, the second switch, the third switch and the fourth switch operate according to the quantized signal, and at least one of the resistor, the first voltage, the common voltage and the second voltage is adjustable.