semiconductor curve tracer for image sensor research

点击翻译按钮获取中文摘要

The Imaging Science Lab at the University of Alberta is developing a "companding" architecture for image sensors and requires a semiconductor curve tracer to do so. In a companding image sensor, the response of a pixel to a light stimulus is not directly proportional to the incident illuminance but depends on the nonlinear characteristic of a load transistor, which compresses the signal in much the same way as the human eye. Once the signal is converted from the analog to the digital domain, it is expanded again so that colour information may be displayed properly. Advantages of the compressing-expanding, or companding, architecture are that it enables high contrast and high speed imaging by exploiting the large-signal or native properties of transistors. The Imaging Science Lab believes this approach will challenge conventional image sensors as technology scales. As microelectronic devices get smaller, it becomes more difficult to obtain linear responses in the analog domain anyway and the digital domain becomes more efficient for signal processing. The successful development of the companding architecture, especially an ability to self-calibrate, depends on a good understanding of current-voltage (I-V) relationships in the diodes and transistors that make up the image sensor. The variation in these I-V curves across an image sensor, and from one image sensor to another, are just as important as the average curve. A semiconductor curve tracer will help to study these relationships. Finally, the VLSI Lab, also at the University of Alberta, will make use of the curve tracer in its research on integrated electronics for microfluidic chips, which have applications in health care and diagnostics.