A Multimodal CMOS Readout IC for SWIR Image Sensors with Dual-Mode BDI/DI Pixels and Column-Parallel Two-Step Single-Slope ADC
This paper proposes a dual-mode CMOS analog front-end (AFE) circuit for short-wave infrared (SWIR) image sensors, which integrates a hybrid readout circuit (ROIC) and a 12-bit two-step single-slope analog-to-digital converter (TS-SS ADC). The ROIC dynamically switches between buffered-direct-injecti...
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MDPI AG
2025-06-01
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| author | Yuyan Zhang Zhifeng Chen Yaguang Yang Huangwei Chen Jie Gao Zhichao Zhang Chengying Chen |
| author_facet | Yuyan Zhang Zhifeng Chen Yaguang Yang Huangwei Chen Jie Gao Zhichao Zhang Chengying Chen |
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| description | This paper proposes a dual-mode CMOS analog front-end (AFE) circuit for short-wave infrared (SWIR) image sensors, which integrates a hybrid readout circuit (ROIC) and a 12-bit two-step single-slope analog-to-digital converter (TS-SS ADC). The ROIC dynamically switches between buffered-direct-injection (BDI) and direct-injection (DI) modes, thus balancing injection efficiency against power consumption. While the DI structure offers simplicity and low power, it suffers from unstable biasing and reduced injection efficiency under high background currents. Conversely, the BDI structure enhances injection efficiency and bias stability via an input buffer but incurs higher power consumption. To address this trade-off, a dual-mode injection architecture with mode-switching transistors is implemented. Mode selection is executed in-pixel via a low-leakage transmission gate and coordinated by the column timing controller, enabling low-current pixels to operate in low-noise BDI mode, whereas high-current pixels revert to the low-power DI mode. The TS-SS ADC employs a four-terminal comparator and dynamic reference voltage compensation to mitigate charge leakage and offset, which improves signal-to-noise ratio (SNR) and linearity. The prototype occupies 2.1 mm × 2.88 mm in a 0.18 µm CMOS process and serves a 64 × 64 array. The AFE achieves a dynamic range of 75.58 dB, noise of 249.42 μV, and 81.04 mW power consumption. |
| format | Article |
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| institution | Kabale University |
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| language | English |
| publishDate | 2025-06-01 |
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| spelling | doaj-art-ff50ead4f3a14d2ab7b11b66eb77fbf52025-08-20T03:58:26ZengMDPI AGMicromachines2072-666X2025-06-0116777310.3390/mi16070773A Multimodal CMOS Readout IC for SWIR Image Sensors with Dual-Mode BDI/DI Pixels and Column-Parallel Two-Step Single-Slope ADCYuyan Zhang0Zhifeng Chen1Yaguang Yang2Huangwei Chen3Jie Gao4Zhichao Zhang5Chengying Chen6School of Opto-Electronic and Communication Engineering, Xiamen University of Technology, Xiamen 361024, ChinaSchool of Opto-Electronic and Communication Engineering, Xiamen University of Technology, Xiamen 361024, ChinaHealth Electronics Center, Institute of Microelectronics (IME) of the Chinese Academy of Sciences, Beijing 100871, ChinaSchool of Opto-Electronic and Communication Engineering, Xiamen University of Technology, Xiamen 361024, ChinaSchool of Opto-Electronic and Communication Engineering, Xiamen University of Technology, Xiamen 361024, ChinaSchool of Opto-Electronic and Communication Engineering, Xiamen University of Technology, Xiamen 361024, ChinaSchool of Opto-Electronic and Communication Engineering, Xiamen University of Technology, Xiamen 361024, ChinaThis paper proposes a dual-mode CMOS analog front-end (AFE) circuit for short-wave infrared (SWIR) image sensors, which integrates a hybrid readout circuit (ROIC) and a 12-bit two-step single-slope analog-to-digital converter (TS-SS ADC). The ROIC dynamically switches between buffered-direct-injection (BDI) and direct-injection (DI) modes, thus balancing injection efficiency against power consumption. While the DI structure offers simplicity and low power, it suffers from unstable biasing and reduced injection efficiency under high background currents. Conversely, the BDI structure enhances injection efficiency and bias stability via an input buffer but incurs higher power consumption. To address this trade-off, a dual-mode injection architecture with mode-switching transistors is implemented. Mode selection is executed in-pixel via a low-leakage transmission gate and coordinated by the column timing controller, enabling low-current pixels to operate in low-noise BDI mode, whereas high-current pixels revert to the low-power DI mode. The TS-SS ADC employs a four-terminal comparator and dynamic reference voltage compensation to mitigate charge leakage and offset, which improves signal-to-noise ratio (SNR) and linearity. The prototype occupies 2.1 mm × 2.88 mm in a 0.18 µm CMOS process and serves a 64 × 64 array. The AFE achieves a dynamic range of 75.58 dB, noise of 249.42 μV, and 81.04 mW power consumption.https://www.mdpi.com/2072-666X/16/7/773CMOS readout integrated circuit (ROIC)buffered direct injection (BDI)direct injection (DI)short-wave infrared (SWIR)two-step single-slope ADC (TS-SS ADC) |
| spellingShingle | Yuyan Zhang Zhifeng Chen Yaguang Yang Huangwei Chen Jie Gao Zhichao Zhang Chengying Chen A Multimodal CMOS Readout IC for SWIR Image Sensors with Dual-Mode BDI/DI Pixels and Column-Parallel Two-Step Single-Slope ADC Micromachines CMOS readout integrated circuit (ROIC) buffered direct injection (BDI) direct injection (DI) short-wave infrared (SWIR) two-step single-slope ADC (TS-SS ADC) |
| title | A Multimodal CMOS Readout IC for SWIR Image Sensors with Dual-Mode BDI/DI Pixels and Column-Parallel Two-Step Single-Slope ADC |
| title_full | A Multimodal CMOS Readout IC for SWIR Image Sensors with Dual-Mode BDI/DI Pixels and Column-Parallel Two-Step Single-Slope ADC |
| title_fullStr | A Multimodal CMOS Readout IC for SWIR Image Sensors with Dual-Mode BDI/DI Pixels and Column-Parallel Two-Step Single-Slope ADC |
| title_full_unstemmed | A Multimodal CMOS Readout IC for SWIR Image Sensors with Dual-Mode BDI/DI Pixels and Column-Parallel Two-Step Single-Slope ADC |
| title_short | A Multimodal CMOS Readout IC for SWIR Image Sensors with Dual-Mode BDI/DI Pixels and Column-Parallel Two-Step Single-Slope ADC |
| title_sort | multimodal cmos readout ic for swir image sensors with dual mode bdi di pixels and column parallel two step single slope adc |
| topic | CMOS readout integrated circuit (ROIC) buffered direct injection (BDI) direct injection (DI) short-wave infrared (SWIR) two-step single-slope ADC (TS-SS ADC) |
| url | https://www.mdpi.com/2072-666X/16/7/773 |
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