Low-Power Tuneable OTA based Low-Pass Filter using 90nm CMOS Technology

Abstract

This work presents a complementary-input fully differential CMOS operational transconductance amplifier (OTA) based low-pass filter for low power biomedical signal processing application. The proposed filter is designed using a 90nm CMOS process and employs a bias voltage control technique in which tuning voltage regulates the bias current and transconductance through NMOS current sink transistor. At a bias voltage of 500 mV and supply voltage of 1V, the filter achieves a maximum gain of 22.56 dB, a cut off frequency of about 270.8 Hz, input referred noise (IRN) of 665 nV/sqrt(Hz) at 1 kHz and power consumption of only 32.91 µW which indicates that the low-frequency response can be effectively tuned by varying the bias voltage. Monte carlo simulation demonstrates negligible deviation of total power consumption against their respective mean value, establishing insensitivity of the filter to the process and mismatch variations. Compared to previously reported filters, the proposed filter offers a low cut-off frequency, and low Input referred noise (IRN) while maintaining low power consumption and provide a basis for selecting a bias condition for low-frequency analog applications.