Patent ID: 7432841

Claim:
An analog-to-digital converter, comprising: a first delta-sigma modulator configured to quantize a most significant bit of an input signal and produce a first quantization error signal, the first delta-sigma modulator comprising: a one-bit analog-to-digital converter in a feedforward path, and a one-bit digital-to-analog converter and a feedback path; and a second multi-stage delta-sigma modulator configured to quantize less significant bits of said input signal, the second multi-stage delta-sigma modulator comprising: a first quantization stage coupled to a difference of said first quantization error signal and a second quantization error signal and configured to quantize next most significant bits of said input signal and produce a third quantization error signal representing a difference between an input and an output of said first quantization stage; a second quantization stage with an input coupled to said third quantization error signal and configured to quantize least significant bits of said input signal and produce said second quantization error signal representing a difference between said input and an output of said second quantization stage; and a first noise-shaping filter coupled to said second quantization error signal, the output of said first noise-shaping filter subtracted from said first quantization error signal to produce said input of said first quantization stage.