Design of a low-power 3rd order notch filter for biomedical applications

Low-power operation and rejection of 50Hz/60Hz power line interference is the prime requirement of notch filter targeted for acquisition of electroencephalogram (EEG) signals. However, achieving low-power operation along with rejection of power line interference using notch filter is difficult task in CMOS technology. In this work, we have proposed a low transconductance quasi-floating bulk (QFB) OTA based 3rd order low-pass notch filter in 0.18 µm standard CMOS process. The proposed 3rd order low-pass notch filter shows passband attenuation of -3.6 dB, stopband attenuation of -13.86 dB, notch of -43.4 dB at 50 Hz, bandwidth of 34.3 Hz and total harmonic distortion (THD) of 1% for input range of 5 mVpp at 8 Hz frequency. The proposed notch filter consumes area of 81990.50 µm2, power of 0.168 µW from ± 0.88 V supply voltage. The proposed notch filter is anticipated to be used in analog front-end systems targeted for detection of biomedical signals such as EEG and electrocardiogram (ECG).