Current-mode circuits for sigma-delta converters

Abstract

This paper presents the design of current-mode blocks to be used in modulator and decimator parts of continuous-time sigma-delta converters. Main blocks of sigma delta converters such as integrator and quantizer have been designed in current-mode. Through current-mode design, quantizer outputs are currents so that there is no need to use a voltage input/current output digital/analog converter in the feedback loop. Moreover, current-mode full-adder and delay elements have been designed which are main components of digital filters. Also a first-order modulator has been implemented and simulated.