A CMOS image sensor using variable reference time domain encoding

M. K. Law; A. Bermak

doi:10.1109/iscas.2007.377943

A CMOS image sensor using variable reference time domain encoding

M. K. Law^*
, A. Bermak

^*Corresponding author for this work

Hong Kong University of Science and Technology

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › peer-review

4 Citations (Scopus)

Abstract

In this paper, a Variable Reference Time Domain Encoding CMOS image sensor is presented. The time domain encoding vision sensor is known to suffer from slow conversion time, especially at low level of illumination. This is due to limited photocurrent generated to discharge the photodiode junction voltage to the reference voltage. A variable referencing scheme is proposed so that the reference voltage will be modulated and bounded by a specified deadline. The pixel consists of a photodiode, an analogue comparator, an 8-bit SRAM, a SR latch, and occupies an area of 32μm × 35μm, with a fill-factor of 12.6% using a 0.35μm CMOS process. Simulation results show that signal conversion can be achieved by using pre-defined threshold voltages. By using four levels of reference voltage and 1/10 of the original conversion time required by the original time domain encoding, over 70% reduction in total integration time can be achieved.

Original language	English
Title of host publication	2007 IEEE International Symposium on Circuits and Systems, ISCAS 2007
Publisher	Institute of Electrical and Electronics Engineers Inc.
Pages	2399-2402
Number of pages	4
ISBN (Print)	1424409209
DOIs	https://doi.org/10.1109/iscas.2007.377943
Publication status	Published - 2007
Externally published	Yes
Event	2007 IEEE International Symposium on Circuits and Systems, ISCAS 2007 - New Orleans, LA, United States Duration: 27 May 2007 → 30 May 2007

Publication series

Name	Proceedings - IEEE International Symposium on Circuits and Systems
ISSN (Print)	0271-4310

Conference

Conference	2007 IEEE International Symposium on Circuits and Systems, ISCAS 2007
Country/Territory	United States
City	New Orleans, LA
Period	27/05/07 → 30/05/07

Access to Document

10.1109/iscas.2007.377943

Cite this

Law, M. K., & Bermak, A. (2007). A CMOS image sensor using variable reference time domain encoding. In 2007 IEEE International Symposium on Circuits and Systems, ISCAS 2007 (pp. 2399-2402). Article 4253159 (Proceedings - IEEE International Symposium on Circuits and Systems). Institute of Electrical and Electronics Engineers Inc.. https://doi.org/10.1109/iscas.2007.377943

@inproceedings{3b76e3b5aaee40d98fd7cfa6e96389cb,

title = "A CMOS image sensor using variable reference time domain encoding",

abstract = "In this paper, a Variable Reference Time Domain Encoding CMOS image sensor is presented. The time domain encoding vision sensor is known to suffer from slow conversion time, especially at low level of illumination. This is due to limited photocurrent generated to discharge the photodiode junction voltage to the reference voltage. A variable referencing scheme is proposed so that the reference voltage will be modulated and bounded by a specified deadline. The pixel consists of a photodiode, an analogue comparator, an 8-bit SRAM, a SR latch, and occupies an area of 32μm {\texttimes} 35μm, with a fill-factor of 12.6\% using a 0.35μm CMOS process. Simulation results show that signal conversion can be achieved by using pre-defined threshold voltages. By using four levels of reference voltage and 1/10 of the original conversion time required by the original time domain encoding, over 70\% reduction in total integration time can be achieved.",

author = "Law, \{M. K.\} and A. Bermak",

year = "2007",

doi = "10.1109/iscas.2007.377943",

language = "English",

isbn = "1424409209",

series = "Proceedings - IEEE International Symposium on Circuits and Systems",

publisher = "Institute of Electrical and Electronics Engineers Inc.",

pages = "2399--2402",

booktitle = "2007 IEEE International Symposium on Circuits and Systems, ISCAS 2007",

address = "United States",

note = "2007 IEEE International Symposium on Circuits and Systems, ISCAS 2007 ; Conference date: 27-05-2007 Through 30-05-2007",

}

Law, MK & Bermak, A 2007, A CMOS image sensor using variable reference time domain encoding. in 2007 IEEE International Symposium on Circuits and Systems, ISCAS 2007., 4253159, Proceedings - IEEE International Symposium on Circuits and Systems, Institute of Electrical and Electronics Engineers Inc., pp. 2399-2402, 2007 IEEE International Symposium on Circuits and Systems, ISCAS 2007, New Orleans, LA, United States, 27/05/07. https://doi.org/10.1109/iscas.2007.377943

A CMOS image sensor using variable reference time domain encoding. / Law, M. K.; Bermak, A.
2007 IEEE International Symposium on Circuits and Systems, ISCAS 2007. Institute of Electrical and Electronics Engineers Inc., 2007. p. 2399-2402 4253159 (Proceedings - IEEE International Symposium on Circuits and Systems).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › peer-review

TY - GEN

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AU - Law, M. K.

AU - Bermak, A.

PY - 2007

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N2 - In this paper, a Variable Reference Time Domain Encoding CMOS image sensor is presented. The time domain encoding vision sensor is known to suffer from slow conversion time, especially at low level of illumination. This is due to limited photocurrent generated to discharge the photodiode junction voltage to the reference voltage. A variable referencing scheme is proposed so that the reference voltage will be modulated and bounded by a specified deadline. The pixel consists of a photodiode, an analogue comparator, an 8-bit SRAM, a SR latch, and occupies an area of 32μm × 35μm, with a fill-factor of 12.6% using a 0.35μm CMOS process. Simulation results show that signal conversion can be achieved by using pre-defined threshold voltages. By using four levels of reference voltage and 1/10 of the original conversion time required by the original time domain encoding, over 70% reduction in total integration time can be achieved.

AB - In this paper, a Variable Reference Time Domain Encoding CMOS image sensor is presented. The time domain encoding vision sensor is known to suffer from slow conversion time, especially at low level of illumination. This is due to limited photocurrent generated to discharge the photodiode junction voltage to the reference voltage. A variable referencing scheme is proposed so that the reference voltage will be modulated and bounded by a specified deadline. The pixel consists of a photodiode, an analogue comparator, an 8-bit SRAM, a SR latch, and occupies an area of 32μm × 35μm, with a fill-factor of 12.6% using a 0.35μm CMOS process. Simulation results show that signal conversion can be achieved by using pre-defined threshold voltages. By using four levels of reference voltage and 1/10 of the original conversion time required by the original time domain encoding, over 70% reduction in total integration time can be achieved.

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M3 - Conference contribution

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SN - 1424409209

T3 - Proceedings - IEEE International Symposium on Circuits and Systems

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BT - 2007 IEEE International Symposium on Circuits and Systems, ISCAS 2007

PB - Institute of Electrical and Electronics Engineers Inc.

T2 - 2007 IEEE International Symposium on Circuits and Systems, ISCAS 2007

Y2 - 27 May 2007 through 30 May 2007

ER -

A CMOS image sensor using variable reference time domain encoding

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