A CMOS low-power wider band Gm-C notch filter for EEG

A CMOS Gm-C Notch filter for powerline interference rejection in EEG systems is described. The pass-band covers all the four bands of brain wave and, with a bandwidth of 2.17 kHz, enables a deep study of the frequencies of less interest. Besides that, a capacitor programmable circuit makes the filter possible to reject with more than 90 dB the powerline interference for 50 Hz or 60 Hz. The notch filter employs operational transconductance amplifiers working in the weak region, with transconductance of 1.259 nA/V, enabling the use of small capacitors for on-chip integration. In this project, we designed a circuit in 0.13 μm CMOS technology, for a 1.0 V power supply and 10 nA bias current. Simulations conducted on CADENCE (Virtuoso Analog Design Environment) show good performance of the filter for filtering the noise in acquired EEG signals.