Readout Front-end Circuits For EEG Acquisition System

EEG signal is an important biological signal, for it contains large amounts ofbiological electric information in human body. EEG applications cover wide areas,including adjuvant therapy, cognitive thinking, brain disease diagnosis, rehabilitationmedicine and military fields. With the improvement of signal process technology andintegrated circuit design, the project acquiring EEG signal to analyse drain’s informationhas been widely researched.This paper presents a low noise, low power, high CMRR and programmable gainreadout front-end circuit. It is divided into two parts: a current balancing IA and anoperational amplifier as gain stage. Through current feedback technology, IA could achievelow power and high CMRR performance. Meanwhile, it could achieve low noisecharacteristics by band-pass filtering technology. And a off chip resistor could provideconfigurable gain. The gain stage is a folded cascade amplifier with a buffer, it provideslarge voltage gain. The readout front-end circuit is implemented with GSMC_R018S6D0CMOS technology and supplied with1.8V DC power. Schematic design, circuitssimulation and layout design is completed with Cadence software. The results indicate thatthe circuit achieves smaller size, higher CMRR, superior BPF characteristics andconvenient configurable gain. More specifically, it shows a greatly improvement in overallperformance and reached a certain level of innovation.