Design of Low Power Notch Filter for Biomedical Applications

Abstract: The most important constraint in the design of Biomedical circuits is suppression of the power line frequency of 60 Hz which is a major interference in proper read out of low frequency ECG and EEG signals. This paper presents the design of low power Notch filter for biomedical applications using 180nm CMOS technology. The filter implementation is based on Tow-Thomas Topology. The filter design is based on highly linear fully differential Operational amplifier having a gain of 96.8dB. A filter design methodology wherein a second order continuous time (CT) filter is designed using a R – 2R ladder resistor is proposed in this paper which reduces the overall silicon area requirement for the resistor implementation. It is demonstrated that a notch depth of 84.79dB is achieved using CT filers. The CT filter consumes a very low power of less than 10.67 μW making it more suitable for bio-medical applications. The proof of concept is demonstrated by post layout simulations on Cadence analog design environment.

Keywords: Notch filter, Low frequency, Tow-Thomas Topology, Operational Amplifier, Resistor ladder, Low power.