A fully on-chip LDO voltage regulator for remotely powered cortical implants

Abstract

This article presents a fully on-chip low-power low drop-out (LDO) voltage regulator dedicated to remotely powered wireless cortical implants. This regulator is stable over the full range of alternating current without the need of dedicated active circuitry and increase in ground current. A new compensation technique is proposed to improve PSRR beyond the performance which can be achieved by regular cascode compensation technique. Measurement results show that the regulator has a load regulation of 0.175V/A, a line regulation of 0.024%, and a PSRR of 37dB at 1MHz power carrier frequency. The output of the regulator settles within 10-bit accuracy of the nominal voltage (1.8V) within 1.6µµs, at full load transition. The output spot noise at 100Hz and 100kHz are 1.1µV/sqrt (Hz) and 390nV/sqrt (Hz), respectively. The total ground current including the bandgap reference circuit is 28µA and the active chip area measures 290µm×360µm in 0.18µm CMOS technology.