Title :
A logarithmic photoreceptor incorporating lateral bipolar transistors for improved matching and dynamic range
Author :
Rowley, Matthew D. ; Harris, John G. ; Lim, Shao-Jen
Author_Institution :
Florida Univ., USA
Abstract :
Offsets and limited dynamic range in the photo-conversion elements of silicon VLSI vision systems limit the overall system performance in low-contrast environments. This paper introduces a new continuous-time, logarithmic photoreceptor which exhibits an improvement in the signal-to-offset ratio at low and medium intensities of 31% and 137% respectively. In addition, the logarithmic receptor exhibits a larger dynamic range than previous continuous-time receptors. Measured performance characteristics will be shown which quantify these improvements. We further show both analytically and through measured results that the offsets decrease as current levels increase
Keywords :
VLSI; analogue processing circuits; computer vision; elemental semiconductors; image matching; photodetectors; phototransistors; real-time systems; silicon; Si; analogue VLSI vision systems; dynamic range; lateral bipolar transistors; logarithmic photoreceptor; low-contrast environments; performance characteristics; signal-to-offset ratio; system performance; Bipolar transistors; Circuits; Current measurement; Dynamic range; Photodiodes; Photoreceptors; Silicon; System performance; Very large scale integration; Voltage;
Conference_Titel :
Circuits and Systems, 1997. ISCAS '97., Proceedings of 1997 IEEE International Symposium on
Print_ISBN :
0-7803-3583-X
DOI :
10.1109/ISCAS.1997.621509
