High Precision Low-Voltage WTA/LTA Circuit and its Applications

Abstract

In this thesis, a novel low-voltage current mode WTA/LTA circuit is proposed for which detects maximum and minimum values from the given current inputs simultaneously. The circuit is developed using cascode current mirrors and a substractor circuit. The cascode current mirror is used to improve the output swing and substractor circuit is used to compute the difference of two input currents. The proposed circuit operates at supply voltage of 1.1V with high precision. The output current is mirrored with transfer error lower than 0.035% while input current is varying from 0 to 40uA. Simulations have been performed with SPICE level 53 (TSMC) parameters in 0.18um CMOS technology. Some of the applications of the proposed WTA/LTA circuit such as half wave rectifier, full wave rectifier and modulus circuit with their simulation results have also been presented. Maximum and Minimum functions are fundamental operations in many nonlinear systems. Most analogue maximum and minimum continuous-time CMOS implementations have been derived from ‘Winner-take-all (WTA) and Looser take all (LTA) circuits. The thesis gives a brief review of different approaches reported by various researchers in literature. Out of these, one of the maximum and minimum circuit has been designed and simulated. The simulated results have also been presented.