Title :
A wide-dynamic-range, low-power photosensor array
Author_Institution :
Div. of Appl. Sci., Harvard Univ., Cambridge, MA, USA
Abstract :
A 32/spl times/32 array of photosensors with pulse frequency outputs uses standard 2 /spl mu/m CMOS technology. The photosensors use pulse-frequency encoding to achieve a linear dynamic range of 10/sup 6/ in optical energy. Power dissipation of the photosensor is proportional to the frequency of the pulse outputs, and under typical illumination and bias conditions, the entire 32/spl times/32 array dissipates <100 nW. A/D conversion of incident optical energy is directly by counting the number of pulses in a fixed time period or by measuring the time interval between successive pulses. Each photosensor element is implemented with a photodiode and low-power CMOS circuitry for pulse frequency encoding and readout. The resulting fill-factor of each 107/spl times/107 /spl mu/m/sup 2/ photosensor is approximately 12%.<>
Keywords :
CMOS integrated circuits; analogue-digital conversion; image coding; image sensors; photodiodes; 100 nW; 2 micron; 32/spl times/32 array; A/D conversion; CMOS technology; low-power CMOS circuitry; low-power photosensor array; photodiode; power dissipation; pulse frequency outputs; pulse-frequency encoding; wide-dynamic-range; CMOS technology; Dynamic range; Encoding; Energy measurement; Frequency; Lighting; Optical pulses; Power dissipation; Pulse measurements; Time measurement;
Conference_Titel :
Solid-State Circuits Conference, 1994. Digest of Technical Papers. 41st ISSCC., 1994 IEEE International
Conference_Location :
San Francisco, CA, USA
Print_ISBN :
0-7803-1844-7
DOI :
10.1109/ISSCC.1994.344657
