Area-Efficient Low-Power Self-Biased Three-Stage OTA Fabricated in 0.6- μ m IGZO-on-Plastic Technology

This work presents a high-efficiency three-stage operational transconductance amplifier (OTA) fabricated in a commercial 0.6-μm Indium Gallium Zinc Oxide (IGZO) thin-film transistor (TFT) technology on a flexible plastic substrate. The architecture leverages a fully self-biased differential input stage combined with a reverse nested Miller compensation with nulling resistor scheme to ensure robust stability under up to 40-pF loads. Operating from a 3-V supply, the OTA consumes only60~μW while driving a 40-pF load, achieving a measured DC gain of 41.2 dB, a unity-gain bandwidth of 200 kHz, and a phase margin of 60.7°. Time-domain measurements demonstrate a 1%-settling time of21~μs and a slew rate of 94 V/ms, with an output swing exceeding 83%. The self-biasing scheme and compensation strategy provide high resilience against process, voltage, and multi-die variations. This design occupies an active area of only 0.042 mm2, and achieves a power consumption of60~μW with a small-signal Figure of Merit of 133.3 kHz·pF/μW, establishing a new performance benchmark for plastic electronics.