A Micropower Low-Noise Neural Recording Front-End Circuit for Epileptic Seizure Detection Chengliang Qian, Student Member , IEEE

Abstract

This paper describes a micropower low-noise neural front-end circuit capable of recording epileptic fast ripples (FR). The front-end circuit consisting of a preampli fier followed by a 6th-order bandpass filter is designed for signal sensing in a fu- ture epileptic deep brain stimulat or. A current-spli tting technique is combined with an output-branch current scaling technique in a folded-cascode amplifier structure to improve the noise and power tradeoff in the preamplifier. In measurements, the preamplifier ex- hibits 39.4 dB DC gain, 0.36 Hz to 1.3 kHz of dB bandwidth, and 3.07 total input-referred noise while consuming 2.4 W from a 2.8 V power supply provided by an on-chip regulator circuit. A noise ef ficiency factor (NEF) of 3.09 is achieved with minimal power consumption and is one of the lowest published to date. The 6th-order follow-the- leader feedback elliptic bandpass filter passes FR signals and provides dB/decade attenuation to out-of-band frequency compone nts. In measurements, the en- tire front-end circuit achieves a mid-band gain of 38.5 dB, a band- width from 250 to 486 Hz, and a total input-referred noise of 2.48 while consuming 4.5 W from the 2.8 V power supply. The front-end NEF achieved is 7.6. To the authors’ knowledge, the pro- posed epileptic seizure- detection system is the first to achieve the FR-recording functionality. Th ec h i pi sf a b r i c a t e di nas t a n d a r d 0.6 m CMOS process. Die size is 0.45 mm .