Operational Amplifier Design for Low-Power IoT Sensor Nodes

With the proliferation of Internet of Things (IoT) devices, energy-efficient analog front-end circuits have become critical to ensure prolonged operation on constrained power budgets.Operational amplifiers (opamps) are core components in sensor signal conditioning circuits and significantly impact overall power consumption and performance.This paper presents a comprehensive design methodology for low-power operational amplifiers tailored for IoT sensor nodes.We explore key design trade-offs between power consumption, gain, bandwidth, and stability.A two-stage CMOS op-amp is designed using 180nm technology, optimized for sub-W operation, rail-to-rail input/output, and moderate gain-bandwidth product.Simulation results show that the proposed design achieves 60 dB gain, a phase margin of 65, 1.2 V supply operation, and consumes only 800 nW, making it ideal for ultra-low power sensor interfaces in IoT applications.