Low-Power CMOS Operational Amplifier Design in 45nm Technology

Energy-efficient design is the backbone of modern electronics, crucial for portable devices and medical systems where every milliwatt counts. This paper presents the design and simulation of a low-power CMOS operational amplifier (OpAmp) implemented in a CMOS technology node, optimized for applications requiring ultra-low power consumption. Unlike conventional OpAmp designs that operate in strong inversion, this work leverages moderate inversion to achieve a trade-off between power efficiency and gain performance, making it highly suitable for sensor interfaces in wearable health monitoring devices, hearing aids, and telemetry systems. The proposed design features a cascade second stage for boosting the overall gain, a dynamically biased differential input stage for improved efficiency, and current mirrors to optimize tail current, ensuring stable operation at low power budgets. Simulated results in Cadence demonstrate an open-loop gain of 67 dB, a gain-bandwidth product of 2.31 MHz, and a power consumption of only 12.5 µW, showcasing its feasibility for power-sensitive applications. By offering an implementation-based validation of OpAmp performance in the 45 nm node, this work closes the gap between high-tech low-power electronics’ theoretical concepts and real-world applications.