A Dynamic Range Enhanced Readout Technique with a Two-Step TDC for High Speed Linear CMOS Image Sensors
This paper presents a dynamic range (DR) enhanced readout technique with a two-step time-to-digital converter (TDC) for high speed linear CMOS image sensors. A multi-capacitor and self-regulated capacitive trans-impedance amplifier (CTIA) structure is employed to extend the dynamic range. The gain...
Main Authors: | , , , |
---|---|
Format: | Article |
Language: | English |
Published: |
MDPI AG
2015-11-01
|
Series: | Sensors |
Subjects: | |
Online Access: | http://www.mdpi.com/1424-8220/15/11/28224 |
id |
doaj-53a54282eae9471cbbe9cb849d93ec35 |
---|---|
record_format |
Article |
spelling |
doaj-53a54282eae9471cbbe9cb849d93ec352020-11-25T00:51:37ZengMDPI AGSensors1424-82202015-11-011511282242824310.3390/s151128224s151128224A Dynamic Range Enhanced Readout Technique with a Two-Step TDC for High Speed Linear CMOS Image SensorsZhiyuan Gao0Congjie Yang1Jiangtao Xu2Kaiming Nie3School of Electronic Information Engineering, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072, ChinaSchool of Electronic Information Engineering, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072, ChinaSchool of Electronic Information Engineering, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072, ChinaSchool of Electronic Information Engineering, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072, ChinaThis paper presents a dynamic range (DR) enhanced readout technique with a two-step time-to-digital converter (TDC) for high speed linear CMOS image sensors. A multi-capacitor and self-regulated capacitive trans-impedance amplifier (CTIA) structure is employed to extend the dynamic range. The gain of the CTIA is auto adjusted by switching different capacitors to the integration node asynchronously according to the output voltage. A column-parallel ADC based on a two-step TDC is utilized to improve the conversion rate. The conversion is divided into coarse phase and fine phase. An error calibration scheme is also proposed to correct quantization errors caused by propagation delay skew within −Tclk~+Tclk. A linear CMOS image sensor pixel array is designed in the 0.13 μm CMOS process to verify this DR-enhanced high speed readout technique. The post simulation results indicate that the dynamic range of readout circuit is 99.02 dB and the ADC achieves 60.22 dB SNDR and 9.71 bit ENOB at a conversion rate of 2 MS/s after calibration, with 14.04 dB and 2.4 bit improvement, compared with SNDR and ENOB of that without calibration.http://www.mdpi.com/1424-8220/15/11/28224CMOS image sensorCTIAwide dynamic rangetwo-step TDCerror calibration |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Zhiyuan Gao Congjie Yang Jiangtao Xu Kaiming Nie |
spellingShingle |
Zhiyuan Gao Congjie Yang Jiangtao Xu Kaiming Nie A Dynamic Range Enhanced Readout Technique with a Two-Step TDC for High Speed Linear CMOS Image Sensors Sensors CMOS image sensor CTIA wide dynamic range two-step TDC error calibration |
author_facet |
Zhiyuan Gao Congjie Yang Jiangtao Xu Kaiming Nie |
author_sort |
Zhiyuan Gao |
title |
A Dynamic Range Enhanced Readout Technique with a Two-Step TDC for High Speed Linear CMOS Image Sensors |
title_short |
A Dynamic Range Enhanced Readout Technique with a Two-Step TDC for High Speed Linear CMOS Image Sensors |
title_full |
A Dynamic Range Enhanced Readout Technique with a Two-Step TDC for High Speed Linear CMOS Image Sensors |
title_fullStr |
A Dynamic Range Enhanced Readout Technique with a Two-Step TDC for High Speed Linear CMOS Image Sensors |
title_full_unstemmed |
A Dynamic Range Enhanced Readout Technique with a Two-Step TDC for High Speed Linear CMOS Image Sensors |
title_sort |
dynamic range enhanced readout technique with a two-step tdc for high speed linear cmos image sensors |
publisher |
MDPI AG |
series |
Sensors |
issn |
1424-8220 |
publishDate |
2015-11-01 |
description |
This paper presents a dynamic range (DR) enhanced readout technique with a two-step time-to-digital converter (TDC) for high speed linear CMOS image sensors. A multi-capacitor and self-regulated capacitive trans-impedance amplifier (CTIA) structure is employed to extend the dynamic range. The gain of the CTIA is auto adjusted by switching different capacitors to the integration node asynchronously according to the output voltage. A column-parallel ADC based on a two-step TDC is utilized to improve the conversion rate. The conversion is divided into coarse phase and fine phase. An error calibration scheme is also proposed to correct quantization errors caused by propagation delay skew within −Tclk~+Tclk. A linear CMOS image sensor pixel array is designed in the 0.13 μm CMOS process to verify this DR-enhanced high speed readout technique. The post simulation results indicate that the dynamic range of readout circuit is 99.02 dB and the ADC achieves 60.22 dB SNDR and 9.71 bit ENOB at a conversion rate of 2 MS/s after calibration, with 14.04 dB and 2.4 bit improvement, compared with SNDR and ENOB of that without calibration. |
topic |
CMOS image sensor CTIA wide dynamic range two-step TDC error calibration |
url |
http://www.mdpi.com/1424-8220/15/11/28224 |
work_keys_str_mv |
AT zhiyuangao adynamicrangeenhancedreadouttechniquewithatwosteptdcforhighspeedlinearcmosimagesensors AT congjieyang adynamicrangeenhancedreadouttechniquewithatwosteptdcforhighspeedlinearcmosimagesensors AT jiangtaoxu adynamicrangeenhancedreadouttechniquewithatwosteptdcforhighspeedlinearcmosimagesensors AT kaimingnie adynamicrangeenhancedreadouttechniquewithatwosteptdcforhighspeedlinearcmosimagesensors AT zhiyuangao dynamicrangeenhancedreadouttechniquewithatwosteptdcforhighspeedlinearcmosimagesensors AT congjieyang dynamicrangeenhancedreadouttechniquewithatwosteptdcforhighspeedlinearcmosimagesensors AT jiangtaoxu dynamicrangeenhancedreadouttechniquewithatwosteptdcforhighspeedlinearcmosimagesensors AT kaimingnie dynamicrangeenhancedreadouttechniquewithatwosteptdcforhighspeedlinearcmosimagesensors |
_version_ |
1725244716423839744 |