Image Sensor with a Sigma-Delta ADC at Every Pixel

Brief Description
This is a high dynamic range CMOS image sensor with very low power usage, having a multiplexed-separated sigma-delta ADC at each pixel.

Applications:
This image sensor is applicable to cell phone cameras, digital still cameras, medical instruments, bar code readers, security and surveillance, video cameras, and HDTV cameras.  One niche market where this technology has particular advantage is in security cameras, which require large dynamic range to record images at widely varying light levels.  A wireless security camera would require low power usage.  Both of these requirements are met by this design. 

Advantages:
This image sensor with a pixel-level Sigma-Delta ADC embodies the advantages of both modern over-sampling sigma-delta ADC's and a low transistor count CMOS imager pixel readout circuits. Due to the over-sampling nature of the architecture, the transistors can be small to enable high resolution with a high fill-factor. This design can be implemented in modern 0.13-&mu; CMOS processing and below. Other digital pixel sensors are restricted to larger 0.25-&mu; processing. The design inherently has high linearity and low power consumption (< 1&nbsp;nW/pixel).  The dynamic range of the design is intrinsically greater than 78&nbsp;dB, or 13&nbsp;bits, and dynamic range up to 100&nbsp;dB (16&nbsp;bits) has been demonstrated.  
  
Patent Information:
Title Country Patent No. Issued Date
Multiplexed-Input-Separated Sigma-Delta Analog-to-Digital Converter Design for Pixel-Level Analog-to-Digital Conversion United States 7,023,369 4/4/2006
Category(s):
Imaging
For Information, Contact:
John FahnerVihtelic
Senior Licensing Manager
University of Rochester
585.276.6600
john.fahner-vihtelic@rochester.edu
Inventors:
Mark Bocko
Zeljko Ignjatovic
Keywords: