A Chopper-Stabilized Amplifier with a Tunable Bandwidth for EEG Acquisition Applications

Abstract

A chopper-stabilized amplifier for bio-potential signal acquisition applications is presented. The proposed design includes an AC-coupled chopper-stabilized amplifier to reduce the 1/f noise and a tunable MOS-capacitor and a tunable pseudo-resistor to control the bandwidth. It employs a positive feedback input impedance boosting loop (IBL) to increase the input impedance and common-mode rejection ratio (CMRR). The proposed amplifier is designed and fabricated using a Magnachip/SK Hynix 0.18 μ m 1 poly-6 metal CMOS process and tested with a DC supply voltage of 1.5 V (VDD of 0.75 V and VSS of-0.75 V). The proposed amplifier achieves a midband gain of 47.6 dB, a CMRR of 105.6 dB, and an input-referred noise power spectral density (PSD) of 120 nV Hz at 100 Hz with a total power dissipation of 855 nW. The noise-efficiency-factor (NEF) of the proposed amplifier is 2.91. The low-pass corner frequency can be tuned from 200 to 500 Hz. The chip area of the proposed amplifier is 0.065 mm2