Title :
Time domain analogue to digital conversion in a digital pixel sensor array
Author :
Kitchen, Alistair ; Bouzerdoum, Abdesselam ; Bermak, Amine
Author_Institution :
Sch.of Eng. & Math., Edith Cowan Univ., Joondalup, WA, Australia
Abstract :
This paper presents a digital pixel sensor array, in which the photodiode sensor, the analogue to digital conversion circuitry, and an 8-bit memory are combined in the 45 /spl mu/m/spl times/45 /spl mu/m pixel, yielding a 12% fill factor. The conversion is performed by measuring the time taken for the photodiode, operating in direct integration mode, to discharge from its reset voltage to a reference voltage. An on chip control circuit is used to compensate for the non-linear relationship between the photocurrent and the integration time. The 64/spl times/64 pixel array is manufactured using a standard 0.35 /spl mu/m, five metal, digital CMOS process.
Keywords :
CMOS image sensors; analogue-digital conversion; array signal processing; discharges (electric); photodiodes; photoemission; system-on-chip; time-varying networks; 8 B; digital CMOS process; digital complementary metal-oxide-semiconductor process; digital pixel sensor array; direct integration mode operation; integration time; nonlinear relationship compensation; on-chip control circuit; photocurrent; photodiode sensor; time domain analogue-to-digital conversion; voltage discharges; CMOS process; Integrated circuit measurements; Manufacturing processes; Performance evaluation; Photoconductivity; Photodiodes; Semiconductor device measurement; Sensor arrays; Time measurement; Voltage;
Conference_Titel :
Electronic Design, Test and Applications, Proceedings. DELTA 2004. Second IEEE International Workshop on
Conference_Location :
Perth, WA, Australia
Print_ISBN :
0-7695-2081-2
DOI :
10.1109/DELTA.2004.10007
