Dynamic Range Extension of CMOS Image Sensor with Column Capacitor and Feedback Structure

Abstract

This paper presents a wide dynamic range complementary metal oxide semiconductor (CMOS) image sensor with column capacitor and feedback structure. The designed circuit has been fabricated by using 0.18ìm 1-poly 6-metal standard CMOS technology. This sensor has dual mode operation using combination of active pixel sensor (APS) and passive pixel sensor (PPS) structure. The proposed pixel operates in the APS mode for high-sensitivity in normal light intensity, while it operates in the PPS mode for low-sensitivity in high light intensity. The proposed PPS structure is consisted of a conventional PPS with column capacitor and feedback structure. The capacitance of column capacitor is changed by controlling the reference voltage using feedback structure. By using the proposed structure, it is possible to store more electric charge, which results in a wider dynamic range. The simulation and measurement results demonstrate wide dynamic range feature of the proposed PPS. Received : Mar. 16, 2015, Revised : Mar. 26, 2015, Apr. 01, 2015, Accepted : Apr. 06, 2015 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License(http://creativecommons.org/ licenses/bync/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Dual-Sensitivity Mode CMOS Image Sensor for Wide Dynamic Range Using Column Capacitors

“…Thus, the dynamic range (DR) of conventional CISs, which are used in mobile applications, has been gradually decreasing. To solve this problem, several techniques have been reported [4][5][6][7][8][9][10][11][12][13][14][15]. The logarithmic response image sensor achieved a very wide DR of 120 dB [4][5][6].…”