A high PSRR, ultra-low power 1.2V curvature corrected Bandgap reference for wearable EEG application

Abstract

A high PSRR, ultra-low power 1.2V voltage supply (VDD) curvature corrected Bandgap reference for Wearable EEG application is described in this paper. The proposed bandgap reference can operate with supply as low as 1V, and provides a supply regulation of 0.113%/V with VDD range of 1.01-2.62V. Piecewise curvature compensation is employed to reduce the temperature coefficient (TC) of bandgap reference from 22.84ppm /°C to 2.295ppm/°C, with a temperature range -10~110°C. The bandgap reference circuit was designed in standard 0.18um CMOS technology where a proportional to absolute temperature (PTAT) and a complementary to absolute temperature (CTAT) current generation circuit were used to generate first order bandgap reference. A non-linear current was generated using PTAT current and CTAT voltage generation circuit and a power supply rejection ratio (PSRR) of 84.62dB (at DC) was achieved to reduce the interference from power supply noise, in order to meet the specifications for wearable wireless EEG sensing systems. The total current consumption of the whole bandgap reference including biasing and startup circuit is only 4.691uA which fits the requirement of battery powered wearable wireless sensing applications.