Design and Simulation of an OTABased GmC Filter with an Instrumentation Amplifier in Cadence

This paper presents the design and simulation of a low-frequency biomedical signal conditioning block implemented in 180 nm CMOS technology. The proposed architecture comprises an instrumentation amplifier at the front end for precise amplification of microvolt-level signals, followed by an Operational Transconductance Amplifier (OTA) configured as a Gm–C low-pass filter for bandwidth limitation and noise suppression. The instrumentation amplifier offers a mid-band gain of approximately 40 dB with a bandwidth of 0.1–100 Hz, making it well-suited for ECG signal acquisition. The OTA-based Gm–C filter offers electronic tunability of cutoff frequency through bias current control. The complete system operates at a 1.8 V supply and consumes approximately 184.7 µW. Simulation results, including AC gain, CMRR, PSRR, phase margin, slew rate, and noise analysis, validate the suitability of the proposed design for low-power wearable biomedical applications.