Design and Optimization of Low-Power CMOS Operational Transconductance Amplifiers for Biomedical Implantable Devices

This works presents an in-depth study on the design, analysis, and optimization of low-power CMOS OTAs suitable for implantable medical electronics. A 90-nm CMOS OTA system has been implemented and extensively expanded from the original reference design. The proposed OTA operates from a single 1-V supply, achieving high gain, low noise, and ultra-low power consumption key requirements for long-term remote monitoring biomedical devices. This work provides a comprehensive review of OTA architectures, low-voltage CMOS operation, subthreshold transistor behavior, and noise optimization techniques. The proposed OTA adopts a two-stage differential architecture with PMOS input devices for enhanced noise performance and subthreshold operation to significantly reduce power. Simulation results demonstrate a gain of 56.6 dB, input-referred noise of 1.22 µVrms, and a total power consumption of only 11.9 µW confirming suitability for implantable ECG and cardiac systems. Extended discussions include design trade-offs, transistor-level optimization, biomedical constraints, and comparisons with other OTA implementations across different CMOS technologies.