A low power and low noise chopper-stabilized amplifier with DC Servo Loop for EEG sensor

In this paper, a low power and low noise chopper stabilized amplifier with DC servo loop (DSL) is presented. For reducing the complexity in designing and lower area consumption, the amplifier is designed with negative resistor. Furthermore, due to its special feature, this amplifier has suitable PSRR and CMRR without any additional circuit to boost them. This amplifier is designed with embedded low pass to evade vast resistor and capacitor as low pass filter. At the end, a DSL circuit is used to eliminate high DC offset of electrode. The chopper amplifier is designed and simulated in 0.18 μm CMOS technology. The proposed chopper amplifier has 47.3 mid-band gain. The bandwidth is from 0.5 to 8.5 kHz. The total input reffered noise in this bandwidth is 5.9 Vrms when the amplifier including DSL consumes just 2.8 μw power. The noise efficiency factor (NEF) is 2.58. According to Monte Carlo simulation results,The PSRR and CMRR are respectively, more than 120 dB and 100 dB. Finally, the flicker noise corner is lower than 4 Hz.

Keywords:

Chopper amplifier , low power , low noise , instrumentation amplifier , biomedical sensor , DC servo loop