Title :
On-chip compensation of dark current in infrared focal plane arrays
Author :
Ng, M.W. ; Chee, Y.H. ; Xu, Y.P. ; Karunasiri, G.
Author_Institution :
Dept. of Electr. & Comput. Eng., Nat. Univ. of Singapore, Singapore
Abstract :
A readout technique for infrared (IR) focal plane arrays (FPAs), involving on-chip compensation of leakage current is presented. This technique employs a tuneable compensation circuit, controlled by a voltage-to-current converter to eliminate the bulk of the leakage current prior to the integration of the weak photo signal at pixel level. To further improve the performance, a correlated double sampling (CDS) circuit is incorporated at the column level to eliminate the fixed pattern noise (FPN) inherent in large sensor arrays with multiple readout lines. A 32×29-element FPA with CMOS sensors was fabricated using 0.8-μm CMOS technology for testing the concept. To mimic the large leakage associated with IR detectors, the testing was carried out under an external light illumination. The results show good compensation of the current caused by the external light and this indicates the effectiveness of the scheme
Keywords :
CMOS image sensors; circuit tuning; compensation; focal planes; infrared detectors; integrated circuit noise; leakage currents; readout electronics; 0.8 micron; 30 mW; 5 V; CMOS sensors; IR detectors; IR focal plane arrays; IR imagers; correlated double sampling circuit; dark current compensation; fixed pattern noise elimination; infrared FPA; infrared focal plane arrays; large sensor arrays; leakage current compensation; multiple readout lines; onchip compensation; readout technique; tuneable compensation circuit; voltage-to-current converter; CMOS technology; Circuit noise; Circuit testing; Dark current; Leakage current; Sampling methods; Sensor arrays; Tunable circuits and devices; Tuned circuits; Voltage control;
Conference_Titel :
Circuits and Systems, 2001. ISCAS 2001. The 2001 IEEE International Symposium on
Conference_Location :
Sydney, NSW
Print_ISBN :
0-7803-6685-9
DOI :
10.1109/ISCAS.2001.921359
