High-pass shaped dither in continuous-time residue generation systems for analog-to-digital converters

A continuous-time residue generation stage, comprising:

• a dither sequence generator to generate a digital dither sequence;
• a dither signal processing part to filter the digital dither sequence and generate a spectrally-shaped analog dither signal;
• a forward path to delay an analog input signal;
• a feedforward path having a quantizer and a digital-to-analog converter, the quantizer to sum the spectrally-shaped analog dither signal and the analog input signal, and to quantize the summed spectrally-shaped analog dither signal and the analog input signal;
• and
• a filter to filter a residue signal generated from outputs of the forward path and the feedforward path.

A method to reduce spurs caused by quantization error in a continuous-time residue generation stage, comprising:

• in a forward path, delaying an analog input signal;
• in a feedforward path,
• injecting a spectrally-shaped analog dither signal at an input of a quantizer,
• quantizing a summed spectrally-shaped analog dither signal and the analog input signal, and
• generating a reconstructed version of the analog input signal based on the quantizing;
• generating a residue signal based on the delayed analog input signal and the reconstructed version of the analog input signal;
• and
• filtering the residue signal.