A 70- $\mu$ m Pitch 8- $\mu$ W Self-Biased Charge-Integration Active Pixel for Digital Mammography

This paper presents a new low-power compact CMOS active pixel circuit specifically optimized for full-field digital mammography. The proposed digital pixel sensor (DPS) architecture includes self-bias capability at ±10% accuracy, up to 15 nA of dark-current autocalibration, built-in test mechanisms, selectable e^-/h⁺ collection, 10-b lossless charge-integration analog-to-digital conversion, more than 1 decade of individual gain tuning for fixed pattern noise cancellation, and a 50-Mb/s digital-only input/output interface. Experimental results for a 70-μm pitch 8-μW DPS cell example are reported in 0.18-μm CMOS 1-polySi 6-metal technology.