Sang-Ho SEO, Min-Woong SEO, Jae-Sung KONG, Jang-Kyoo SHIN^*, and Pyung CHOI

Department of Electronics, Kyungpook National University, 1370 Sankyuk-dong, Buk-ku, Deagu 702-701, Korea

(Received March 7, 2008; Accepted September 9, 2008)

In this paper, a pseudo 2-transistor active pixel sensor (APS) has been designed and fabricated by using an n-well/gate-tied p-channel metal oxide semiconductor field effect transistor (PMOSFET)-type photodetector with built-in transfer gate. The proposed sensor has been fabricated using a 0.35 μm 2-poly 4-metal standard complementary metal oxide semiconductor (CMOS) logic process. The pseudo 2-transistor APS consists of two NMOSFETs and one photodetector which can amplify the generated photocurrent. The area of the pseudo 2-transistor APS is 7.1 × 6.2 μm². The sensitivity of the proposed pixel is 49 lux/(V·s). By using this pixel, a smaller pixel area and a higher level of sensitivity can be realized when compared with a conventional 3-transistor APS which uses a pn junction photodiode.

Key words: CMOS image sensor, active pixel sensor, n-well/gate-tied PMOSFET-type photodetector with built-in transfer gate

^*E-mail address: jkshin@ee.knu.ac.kr