3 Transistor Active Pixel Sensor - Ermal...

In CMOS using AMI-05 Process3 Transistor Active Pixel Sensor

Ermal Dreshaj, B.S. Computer EngineeringDaniel Saab, Ph.D. Computer Engineeringermal@case.eduCase Western Reserve University

CMOS Active Pixel Sensor Used in a variety of applicationsCommercial (Photography)Government/Defense (Nightvision)Research/Medical/Scientific (IR Analysis)

Main competitor: Charge Coupled DeviceCheaper to manufacture than CCD.Quality now approaching that of CCD.CMOS can integrate sensing with analog and

digital processing down to the pixel level.

CMOS Image Sensor Theory

Source: Wikimedia Commonshttp://commons.wikimedia.org/wiki/File:CMOS_Image_Sensor_Mechanism_Illustration.svg

Photodiode in CMOS

Photo-generated carriers in a semiconductor.

n-

P-sub.

hv = hc/λ

Photogate layout used for the 3T-APS design.

Holes

Electrons

3T-APS Design

Source: Wikimedia Commonshttp://en.wikipedia.org/wiki/File:Aps_pd_pixel_schematic.svg

n- well photogate

3T-APS Design

3T-APS Circuit Simulation

3T-APS Circuit Simulation

3T-APS Layout 1 Pixel

Photogate n- well

N-Well to Substrate Capacitance (AMI05): 92 aF/m2

λ = 0.35 µm, Aphotogate = 62.825 * 21.525 = 1352.31 µm2

Cphotogate = 124.41 fF

3T-APS Layout Simulation

3T-APS Layout Simulation

Bibliography

Ohta, Jun. Smart CMOS Image Sensors and Applications. CRC Press. 2008.

Fossum, Eric R. CMOS Image Sensors:Electronic Camera-On-A-Chip. IEEE Transactions on Electronic Devices, Vol. 44, No. 10, October 1997.

El Gamal, Abbas and Elthoukhy, Helmy. CMOS Image Sensors. IEEE Circuits and Devices Magazine. May/June 2005.

Special Thanks

• Steven Majerus, Ph.D. Student Electrical Engineering, Case Western Reserve University– LTSPICE and L-EDIT software training, and

assistance with design and layout.