Performance evaluation of an architecture for the characterisation of photo-devices: design, fabrication and test on a CMOS technology
In this report, the performance of a particular pixel's architecture is evaluated. It consists mainly of an optical sensor coupled to an amplifier. The circuit contains photoreceptors such as phototransistors and photodiodes. The circuit integrates two main blocks: (a) the pixel architecture, c...
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Published in | International journal of electronics Vol. 98; no. 3; pp. 322 - 337 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Abingdon
Taylor & Francis
01.03.2011
Taylor & Francis LLC |
Subjects | |
Online Access | Get full text |
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Summary: | In this report, the performance of a particular pixel's architecture is evaluated. It consists mainly of an optical sensor coupled to an amplifier. The circuit contains photoreceptors such as phototransistors and photodiodes. The circuit integrates two main blocks: (a) the pixel architecture, containing four p-channel transistors and a photoreceptor, and (b) a current source for biasing the signal conditioning amplifier. The generated photocurrent is integrated through the gate capacitance of the input p-channel MOS transistor, then converted to voltage and amplified. Both input transistor and current source are implemented as a voltage amplifier having variable gain (between 10dB and 32dB). Considering characterisation purposes, this last fact is relevant since it gives a degree of freedom to the measurement of different kinds of photo-devices and is not limited to either a single operating point of the circuit or one kind and size of photo-sensor. The gain of the amplifier can be adjusted with an external DC power supply that also sets the DC quiescent point of the circuit. Design of the row-select transistor's aspect ratio used in the matrix array is critical for the pixel's amplifier performance. Based on circuit design data such as capacitance magnitude, time and voltage integration, and amplifier gain, characterisation of all the architecture can be readily carried out and evaluated. For the specific technology used in this work, the spectral response of photo-sensors reveals performance differences between phototransistors and photodiodes. Good approximation between simulation and measurement was obtained. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0020-7217 1362-3060 |
DOI: | 10.1080/00207217.2010.538901 |