JSSC 2007第10期Data Converters0.5μm

CMOS Camera With In-Pixel Temporal Change Detection and ADC

提出一种90x90像素的CMOS相机，具备像素级时间变化检测和ADC功能。

0.5μm 3M2P CMOS, 4.2mW, 30fps, 2.1%变化灵敏度

CMOS相机像素级检测ADC时间变化检测数据压缩

▸创新点1：像素级嵌入式差分与比较技术，通过在像素内部集成差分电路和比较器，实现了实时变化检测，显著降低了数据传输量（典型压缩率达20倍），同时支持可调阈值以适应不同场景需求。

▸创新点2：nMOS-only 6T 2C像素设计，采用仅nMOS晶体管的6晶体管2电容结构，简化了像素布局（25μm×25μm），在0.5μm CMOS工艺下实现高集成度，同时提供模拟强度输出和数字变化标志的双模功能。

▸创新点3：像素级电容耦合比较器兼ADC的创新电路设计，将比较功能与模数转换融合，通过电容耦合实现阈值可编程的异步量化，在30fps帧率下仅消耗4.2mW功耗，灵敏度达2.1%（1.7μW/cm²光照条件）。

▸创新点4：系统级能效优化方案，通过变化检测触发选择性数据读出机制，结合光栅扫描输出门控，动态减少无效数据传输，在保持图像重建质量的同时实现低功耗（4.2mW）与高帧率（30fps）的平衡。

Abstract

An array of 90 90 active pixel sensors (APS) with pixel-level embedded differencing and comparison is presented. The nMOS-only 6T 2C 25 m 25 m pixel provides both analog readout of pixel intensity and a digital ﬂag indicating temporal change at variable thresholds. Computation is performed through a pixel-level capacitively coupled comparator which also func- tions as analog-to-digital converter. The chip, fabricated in a 0.5 m 3M2P CMOS, process consumes 4.2 mW of power while operating at 30 fps. Change sensitivity is 2.1% at an illumination of 1.7 W/cm /50. Gating of raster-scanned pixel output by change detection typically produces a 20-fold compression in the data stream, depending on image conditions and reconstruction quality set by the change detection threshold.