Abstract: A MASH type sigma delta AD converter includes a modulator, an analog filter filtering an extraction signal obtained by extracting a probe signal and an quantization error generated in a quantizer within a sigma delta modulator, a low speed AD converter performing an AD conversion of an output signal of the analog filter, a first adaptive filter searching for a transfer function of the sigma delta modulator, a second adaptive filter searching for a transfer function from an output of the modulator to the low speed AD converter via the analog filter, and a noise cancellation circuit cancelling the probe signal and the quantization error included in an output signal of the quantizer using the search results by the first and second adaptive filters.

Abstract: A MASH type sigma delta AD converter includes a modulator, an analog filter filtering an extraction signal obtained by extracting a probe signal and an quantization error generated in a quantizer within a sigma delta modulator, a low speed AD converter performing an AD conversion of an output signal of the analog filter, a first adaptive filter searching for a transfer function of the sigma delta modulator, a second adaptive filter searching for a transfer function from an output of the modulator to the low speed AD converter via the analog filter, and a noise cancellation circuit cancelling the probe signal and the quantization error included in an output signal of the quantizer using the search results by the first and second adaptive filters.