Patent ID: 7355540

Claim:
A multi stage noise shaping quantizer, comprising: a first noise shaping quantizer that includes a first local quantizer which quantizes an input signal and a limiter which limits an output range of said first local quantizer, said first noise shaping quantizer performs noise shaping operation to the input signal; a second noise shaping quantizer that can input a first quantization error which occurs due to quantization operation at said first local quantizer and a limit error which occurs due to a limitation operation to the output range at said limiter as an input and performs noise shaping operation to the input; a differentiator that differentiates an output of said second noise shaping quantizer corresponding to a noise shaping order of said first noise shaping quantizer; an adder that adds an output of said differentiator to an output of said first noise shaping quantizer and output the resultant of the addition; and an amplitude controller that limits an amplitude of the limit error which is to be inputted to said second noise shaping quantizer according to an output of said first local quantizer and an feedback output of said second noise shaping quantizer.