• Journal of Semiconductors
  • Vol. 42, Issue 5, 052402 (2021)
Zhiqiang Ma1, Zhong Wu1, and Yue Xu1、2
Author Affiliations
  • 1College of Electronic and Optical Engineering & College of Microelectronics, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
  • 2National and Local Joint Engineering Laboratory of RF integration & Micro-Assembly Technology, Nanjing 210023, China
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    DOI: 10.1088/1674-4926/42/5/052402 Cite this Article
    Zhiqiang Ma, Zhong Wu, Yue Xu. Compact SPAD pixels with fast and accurate photon counting in the analog domain[J]. Journal of Semiconductors, 2021, 42(5): 052402 Copy Citation Text show less

    Abstract

    A compact pixel for single-photon detection in the analog domain is presented. The pixel integrates a single-photon avalanche diode (SPAD), a passive quenching & active recharging circuit (PQARC), and an analog counter for fast and accurate sensing and counting of photons. Fabricated in a standard 0.18 µm CMOS technology, the simulated and experimental results reveal that the dead time of the PQARC is about 8 ns and the maximum photon-counting rate can reach 125 Mcps (counting per second). The analog counter can achieve an 8-bit counting range with a voltage step of 6.9 mV. The differential nonlinearity (DNL) and integral nonlinearity (INL) of the analog counter are within the ± 0.6 and ± 1.2 LSB, respectively, indicating high linearity of photon counting. Due to its simple circuit structure and compact layout configuration, the total area occupation of the presented pixel is about 1500 μm2, leading to a high fill factor of 9.2%. The presented in-pixel front-end circuit is very suitable for the high-density array integration of SPAD sensors.
    $ \Delta{{Q }} = { (V_{\rm{dd}} }- {{V_{\rm{c}}}} - {{\rm{V}}_{{\rm{TH,MN4}}}}{\rm{)}} {C_{\rm p}}, $ (1)

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    $ \Delta {{{V}}_{{\rm{Out}}}} = \frac{{\Delta {{Q}}}}{{{C}}} = \frac{{\left( {{{V}}_{\rm{dd}} - {{V}}_{\rm{c}} - {{{V}}_{{\rm{TH}},{\rm{MN4}}}}} \right) {C_{\rm{p}}}}}{{{C}}}. $ (2)

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    ${\rm{DNL}} = \frac{{{{{V}}_{{i}}}-{{{V}}_{{{i}} - 1}}-{{{V}}_{{\rm{LSB}}}}}}{{{{{V}}_{{\rm{LSB}}}}}},$(3)

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    ${\rm{INL}} = \frac{{{{{V}}_{{i}}} - {{{V}}_{\rm{0}}} - {{i}}{{{V}}_{{\rm{LSB}}}}}}{{{{{V}}_{{\rm{LSB}}}}}},$(4)

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    Zhiqiang Ma, Zhong Wu, Yue Xu. Compact SPAD pixels with fast and accurate photon counting in the analog domain[J]. Journal of Semiconductors, 2021, 42(5): 052402
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