CMOS-Compatible Oxide TFT-Based 2T-2C Near-Pixel Analog Compute Cell with ADC/DAC-Free Sensor Interface for Energy-Efficient Feature Extraction

Abstract

This work presents a CMOS-compatible 2T-2C near-pixel compute cell based on oxide TFTs with an ADC/DAC-free sensor interface, enabling energy-efficient analog-domain feature extraction for vision systems. The cell integrates IGZO TFTs and HfO2 capacitors to support signed-weight MAC operations without requiring ADC/DAC. A comparator circuit allows direct analog-to-pulse conversion from a photodiode, enabling one-to-one sensor-to-cell mapping. The fabricated device demonstrates linear weight updates, strong retention, and calibrated MAC accuracy (R2 = 0.992). Compared to 2T-0C, it achieves up to 93% lower power and up to 43% smaller footprint in peripheral circuits. CNN simulations using 2T-2C-based feature maps achieve 99.6% classification accuracy, highlighting its potential for low-power, high-accuracy near-sensor vision.