A High-Performance Two-Stage OTA for Low Frequency Signal Amplification in Power Constrained Systems

This paper introduces a high-performance two-stage operational transconductance amplifier (OTA) designed to achieve superior stability and noise performance while operating under stringent power constraints. Existing OTA designs struggle with stability, power efficiency, and noise suppression trade-offs, making them less effective for precision analog applications. The proposed OTA addresses these limitations through an advanced transconductance-biasing approach and optimized compensation techniques to ensure a high phase margin, reduced distortion, and a robust gain-bandwidth product (GBW). Implemented in 90-nm CMOS technology with an 800mV supply voltage, the OTA is optimized for applications such as health monitoring, wearable devices, and low-power sensor networks, where energy efficiency and signal fidelity are critical. The design effectively tackles key challenges such as noise suppression, power efficiency, and precise low-frequency signal amplification. Simulation results obtained using Cadence Spectre demonstrate a common-mode gain of 89 dB, a GBW of 1.28 MHz, and a phase margin of 63°. Additionally, the OTA achieves a common-mode rejection ratio (CMRR) exceeding 100 dB and an input-referred noise of 17 pV/√Hz, with a power dissipation of just 1.9 μW and a Power Supply Rejection Ratio (PSRR) of 90 dB. These results underscore the OTA's ability to amplify very low-frequency signals with high precision, making it an ideal solution for power-constrained systems requiring reliable and accurate performance. Despite advancements in OTA architectures, prior research has highlighted significant challenges in achieving high gain and low noise while maintaining an optimal trade-off between bandwidth and stability. Here the proposed OTA presents a novel approach that balances stability, gain, bandwidth, and power efficiency.