Architectures for High Dynamic Range, High Speed Image Sensor Readout Circuits

Kunal Ghosh, Department of Electrical Engineering, Stanford University, Stanford, CA - USA

Abstract: Infrared imaging has recently been finding a growing range of applications in the tactical, industrial, scientific, medical, and automotive arenas. The stringent performance requirements of many of these applications warrant the development of precision high dynamic range, high speed focal plane arrays. The readout circuits for these image sensors must also achieve high linearity and SNR at low power consumption. In particular, certain applications require IR image sensors that can operate at 1000 frames/sec and achieve over 120dB dynamic range and 60dB SNR with low power consumption. These requirements are over four orders of magnitude higher than what can be achieved with existing sensors.

I will first present our group's work in quantitatively analyzing previous high dynamic range image sensor architectures, developed for visible range imaging, and discuss why these schemes cannot meet the performance demands of IR imaging. I will then present Folded Multiple Capture, a new architecture that our group developed which combines the high dynamic range and high speed of synchronous self-reset with the high SNR of multiple capture, and that can meet stringent IR performance requirements. Low power consumption is achieved while maintaining high SNR by using signal processing to relax the demands on the analog front-end. I will conclude by describing an FMC prototype, targeted for 3D-IC IR focal plane arrays, that demonstrates 138dB dynamic range and 60dB SNR at 1000 frames/sec with energy consumption of 25.5nJ per pixel readout.

About the speaker: Kunal Ghosh received the B.S.E in Electrical Engineering and the B.S in Management from the School of Engineering and Applied Sciences and the Wharton School, respectively, at the University of Pennsylvania, Philadelphia, PA, in 2004 (summa cum laude). He received the M.S in Electrical Engineering from Stanford University, Stanford, CA, in 2006, where he is currently working towards his Ph.D under the supervision of Prof. Abbas El Gamal. His current research interests include image sensor architectures, biomedical imaging, carbon nanotube sensors, and device scaling.

During the summer of 2001, Kunal Ghosh was a Visiting Research Associate with the VLSI Research Group at the University of Toronto, Toronto, Canada. During the summers of 2002 and 2004, he was with the Mass Storage Group at Agere Systems, Allentown, PA. He spent the summer in between with McKinsey & Co., Toronto, Canada. Since September 2004, he has been a Research Assistant in the Department of Electrical Engineering at Stanford University.

 

Download visuals (2.4 MB pdf)