A direct analog-to-residue converter

The design of residue converters is an important area of research among RNS based systems. Currently, an analog signal is first converted into binary and then to residue using a binary-to-residue converter. To overcome the inefficiencies due to this two step process, two novel approaches for the design of a direct analog-to-residue (A/R) converter are presented. They are based on the successive approximation as well as the flash conversion approach. In the former, two analog-to-digital (A/D) converters are cascaded with minimal modifications providing a conversion speed very close to that of a conventional A/D converter. In the latter an iterative technique as well as the principle of subranging are successfully applied to generate the first residue. The remaining residues in both approaches are generated by adding a few module adders, and a small look-up table that uses only a very small percentage of the entire chip area.