Oversampling sigma-delta modulator

An oversampling converter with sampling frequency sufficiently higher than an input signal frequency comprising N integrators (N is an integer not less than 2) in parallel for integrating a difference between an input terminal signal and a feedback signal;

• a quantizer for quantizing an output from each of said N integrators;
• means for converting an output from said quantizer to said feedback signal;
• means for detecting a (n-1)th quantization error generated by said quantizer when said quantizer quantizes an output from a (n-1)th integrator (n is an integer of 2 to N) of said N integrators;
• wherein a first loop output signal is generated at an output terminal of said quantizer when an output of a first integrator of said N integrators is quantized by said quantizer, and a nth loop output signal is generated at an output terminal of said quantizer when an output of a nth integrator of said N integrators is quantized by said quantizer;
• a first switch for selectively supplying an input signal as said input terminal signal to said first integrator or supplying said (n-1)th quantization error as said input terminal signal to said nth integrator;
• a second switch for selectively supplying said first loop output signal to a delay or supplying said nth loop output signal to a nth differentiator with a transfer function of a reciprocal number of a product of transfer functions of said first to (n-1)th integrators;
• an adding means for adding outputs from said differentiators to said first loop output signal from said delay;
• and a switch control means for controlling said first and second switches so that said input signal and said (n-1)th quantization error are supplied in sequence to the first integrator and said nth integrator, and said first loop output signal and said nth loop output signal are supplied in sequence to said delay and said nth differentiator.