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

Design of a 3um pixel linear CMOS sensor for earth observation
Design of a 3um pixel linear CMOS sensor for earth observation
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
Linear photosensor, CMOS, photodiode, Earth observation
350-357
Morrissey, Q R
bbd4e8b3-b402-4f83-843a-3173d032625b
Waltham, N R
c9c3a4e2-63fa-49a1-a2ef-478fa70014a5
Turchetta, R
c9ab33e2-21a6-4360-83ff-409eb1fc8a60
French, M J
d7b2deb6-d21f-4a35-a73d-c757ac388444
Bagnall, D M
5d84abc8-77e5-43f7-97cb-e28533f25ef1
Al Hashimi, B M
0b29c671-a6d2-459c-af68-c4614dce3b5d
Morrissey, Q R
bbd4e8b3-b402-4f83-843a-3173d032625b
Waltham, N R
c9c3a4e2-63fa-49a1-a2ef-478fa70014a5
Turchetta, R
c9ab33e2-21a6-4360-83ff-409eb1fc8a60
French, M J
d7b2deb6-d21f-4a35-a73d-c757ac388444
Bagnall, D M
5d84abc8-77e5-43f7-97cb-e28533f25ef1
Al Hashimi, B M
0b29c671-a6d2-459c-af68-c4614dce3b5d

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), pp. 350-357.

Record type: Article

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

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More information

Published date: December 2003
Keywords: Linear photosensor, CMOS, photodiode, Earth observation
Organisations: Nanoelectronics and Nanotechnology, Electronic & Software Systems

Identifiers

Local EPrints ID: 258670
URI: http://eprints.soton.ac.uk/id/eprint/258670
PURE UUID: fc3ace88-b77a-471a-b022-d60fb7c22932

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Date deposited: 10 Dec 2003
Last modified: 18 Jul 2017 09:31

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Contributors

Author: Q R Morrissey
Author: N R Waltham
Author: R Turchetta
Author: M J French
Author: D M Bagnall
Author: B M Al Hashimi

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