Design of Current Comparators and its Application as ADC

Abstract

With the development of current-mode applications, the mixed-mode circuits are gaining in importance because of the necessity of optimizing the interface between the sub-blocks, which are working in different modes i.e current mode and voltage mode. This thesis presents the design of high speed, high resolution and wide input range current comparator that converts the current input data into equivalent binary voltage levels. New current comparator structures were proposed and analyzed and were compared to existing current comparator in terms of parameters like propagation delay, resolution, power dissipation etc.

Applications such as image sensory information processing, control and instrumentation rely on direct input current processing capability where current mode ADC has a natural advantage. A current mode flash analog to digital converter (ADC) with 4-bit resolution was implemented using proposed current comparator. All the proposed circuits are verified for the functionality using SPICE and 0.18μm TSMC CMOS technology parameters.