Title :
A Current-Mode Comparator for Digital Calibration of Amorphous Silicon AMOLED Displays
Author :
Chaji, G.Reza ; Nathan, Arokia
Author_Institution :
Electr. & Comput. Dept., Univ. of Waterloo, Waterloo, ON
fDate :
7/1/2008 12:00:00 AM
Abstract :
We present a digital calibration driving scheme for stabilizing the uniformity of large area amorphous silicon active-matrix organic light emitting diode displays. A current-mode analog-to-digital converter (ADC) is used to extract the differential aging of the individual pixels. For the ADC, a configurable current comparator is designed that employs the output buffer of the source driver to reduce the die area. The comparator and pixel circuit were fabricated in 0.8-mum high-voltage CMOS and amorphous silicon technologies, respectively. Analysis and measurement results show a calibration refresh time of 2 s for a high-definition display (1920 times RGB times 1080). Moreover, the pixel current is highly stable despite a 5-V shift in the threshold voltage of the thin-film transistor driver.
Keywords :
CMOS integrated circuits; LED displays; amorphous semiconductors; analogue-digital conversion; calibration; current comparators; driver circuits; elemental semiconductors; organic light emitting diodes; silicon; thin film transistors; 0.8-mum high-voltage CMOS; ADC; Si; amorphous silicon AMOLED display; analog-digital converter; calibration refresh time; current-mode comparator; die area; digital calibration; high-definition display; large area amorphous silicon active-matrix organic light emitting diode display; pixel circuit; pixel current; pixel differential aging; source driver output buffer; thin-film transistor driver; threshold voltage; Active-matrix organic light emitting diode (AMOLED); amorphous silicon (a-Si); current calibrator; current-mode circuit; digital calibration; thin-film transistor (TFT);
Journal_Title :
Circuits and Systems II: Express Briefs, IEEE Transactions on
DOI :
10.1109/TCSII.2008.921586
