Design of a 3um pixel linear CMOS sensor for earth observation


Morrissey, Q R, Waltham, N R, Turchetta, R, French, M J, Bagnall, D M and Al Hashimi, B M (2003) Design of a 3um pixel linear CMOS sensor for earth observation. Nuclear Instruments and Methods in Physics Research, A, (512), 350-357.

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Description/Abstract

A visible wavelength linear photosensor featuring a pixel size of 3um has been designed for fabrication using commercial 0.25um CMOS technology. For the photo-sensing element, the design uses a special "deep N-well" in P-epi diode offered by the foundry for imaging devices. Pixel reset is via an adjacent p-FET, thus allowing high reset voltages for a wide pixel voltage swing. The pixel voltage is buffered using a voltage-follower op-amp and a sampling scheme is used to allow correlated double sampling (CDS) for removal fo reset noise. Reset and signal levels are buffered through a 16:1 multiplexer to a switched capacitor amplifier which performs the CDS function. Incorporated in the CDS circuit is a programmable gain of 1-8 for increased signal-to-noise ratio at low signal levels. Data output is via 4 analogue output deivers for off-chip conversion. Each driver supplies a differential output voltage with a +/- IV swing for 6.25kHz. This gives a peak data rate at each output driver of 10M sample/s. The device will operate on a 3.3V supply and will dissipate approximately 950mW. Simulations indicate an equivalent noise charge at the pixel of 66.3e- for a full well capacity of 255,000e-, giving a dynamic range of 71.7dB

Item Type: Article
Keywords: Linear photosensor, CMOS, photodiode, Earth observation
Divisions: Faculty of Physical Sciences and Engineering > Electronics and Computer Science > Electronic & Software Systems
Faculty of Physical Sciences and Engineering > Electronics and Computer Science > NANO
ePrint ID: 258670
Date Deposited: 10 Dec 2003
Last Modified: 27 Mar 2014 20:01
Further Information:Google Scholar
URI: http://eprints.soton.ac.uk/id/eprint/258670

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