Binary hysteretic/proteretic delta sigma modulator

A new type of delta-sigma modulator which operates in reverse hysteresis (proteresis) mode is proposed. In this mode, it brings in attractive advantages for reduced feedback delay and ultra high speed optical implementations. We have investigated the switching periods of the hysteretic delta-sigma modulator under the impact of positive feedback and impact of positive delay on the system. A comparison between these two systems and the reverse HDSM (proteresis DSM) is established. We derive the theoretical analysis of all the important parameters. The HDSM and reverse HDSM (proteresis DSM) architecture demonstrates high speed A/D conversion under some special specifications such as : (1) all signals within the modulator are nonnegative for a given bounded input; (2) no sample-and-hold switch required because of utilizing a bi-stable switch with hysteresis; (3) the input signal has almost a linear relationship with the time-averaged output. The system performances are evaluated by simulations and the results are compared with the theoretical analysis.