A high speed tracking quantizer for Continuous-Time multi-bit sigma delta modulators

Multi-bit feedback has been conventionally adopted for the implementation of high performance Continuous Time Sigma Delta modulators (CTSDMs) for relaxing multiple design requirements for the system. The need for speed has rendered a large portion of the power budget to be assigned to the quantizer comparators, which often is implemented with the flash architecture. Previous researches had proposed the concept of a tracking quantizer to reduce the number of comparators but are primarily more suited for low speed applications. In this paper, a novel technique to implement the tracking capability for high speed is presented. The simplicity of the proposed circuit results in good speed performance with power reduction to the overall multi-bit quantizer design.