A 45nm CMOS OTA-Based Low-Pass Filter Designed in Cadence Virtuoso

Low-pass filters play an important role in biomedical applications because they suppress high-frequency noise and retain meaningful low-frequency signals. The filters enhance signal quality during electrocardiogram (ECG) processing, whose signals range from 0.05 to 100 Hz. Operational transconductance amplifiers (OTAs) are most suited for these kinds of applications based on their low power requirements, high efficiency, and variable transconductance. Apart from ECG, OTAs are also useful in electromyography (EMG) and electroencephalography (EEG) signal processing. Active-RC filters for high accuracy frequency responses such as Butterworth and Chebyshev or cascade OTA-C stages for filtering of higher order can be used to implement OTA-based low-pass filters. For battery-powered medical devices, choosing a proper cutoff frequency, having a large dynamic range, and low power consumption are the most important design constraints. In order to implement with high accuracy, efficiency, and effective noise rejection, this paper investigates the design and implementation of an OTA-based low-pass filter specially implemented for biomedical purposes.