Application of dynamic counter circuits in programmable digital pixel sensor architectures

In this paper, a high dynamic range digital pixel sensor (DPS) is presented. Each pixel receives light illumination and converts the intensity level to a digital code. The analog-to-digital conversion is performed in-pixel. The pixel structure incorporates light to pulse signal converter and compact in-pixel dynamic counter to convert the pulse signal to binary coded data. Different variations of the custom design dynamic counters are analyzed in a 0.18 mu m technology, and their application in the DPS is investigated. It is shown that due to the limited clock frequency required in the sensor pixel, the dynamic counter can be incorporated as a pulse to binary code converter. Performance specifications such as power consumption, dynamic range and resolution of the presented structure are investigated using a 100 x 100 pixel sensor. The presented sensor is an effective solution for use in digital field programmable smart image sensors and vision chips since the pixel output is a regular binary code while no global digital counter bus is required. The fill factor of the presented design remains close to that of typical DPSs. Copyright (C) 2013 John Wiley & Sons, Ltd.