A Delta-Readout Scheme for Low-Power CMOS Image Sensors With Multi-Column-Parallel SAR ADCs

作者：Kim Hyeon June^*; Hwang Sun Il; Kwon Ji Wook; Jin Dong Hwan; Choi Byoung Soo; Lee Sang Gwon; Park Jong Ho; Shin Jang Kyoo; Ryu Seung Tak

来源：IEEE Journal of Solid-State Circuits, 2016, 51(10): 2262-2273.

DOI：10.1109/JSSC.2016.2581819

• CMOS image sensor (CIS)
• image-dependent power savings
• delta-readout (Delta-readout) scheme
• multi-column-parallel (MCP)
• successive-approximation register analog-to-digital converter (SAR ADC)

This paper presents a power-saving readout scheme for CMOS image sensors (CISs) that utilizes the image properties. The proposed delta-readout (Delta-readout) scheme reads the signal difference between two pixels located next to each other (Delta(pixel)) by utilizing the most significant bits (MSBs) information of the previous pixel. By effectively reducing the dynamic range of the signal, compensated by the Delta-window checking, the proposed Delta-readout scheme can reduce the effective number of decision cycles in a successive-approximation register (SAR) analog-to-digital converter (ADC) and reduce the power consumption while preserving the ADC performance. A prototype QQVGA CIS with ten 10-bit SAR ADCs in a multi-column-parallel (MCP) configuration was fabricated in a 0.18 mu m 1P4M CIS process with a 4.4 mu m pixel pitch, where each single ADC occupies an area of 70 mu m x 500 mu m. The measurement results of the implemented prototype CIS showed a maximum power-saving of 26% with a figure-of-merit (FoM) for ADC of 15 fJ/conversion-step.

• 出版日期2016-10