Highly-sensitive SPAD and APD devices for extremely low light conditions and augmented sensitivity

27-06-2019 | X-FAB | Test & Measurement

X-FAB Silicon Foundries has APD and SPAD products for usage in scenarios where there are remarkably low light conditions to battle with and augmented sensitivity is required, as well as tight timing resolutions required.


Based on the company’s 180nm high-voltage XH018 process, these function block devices provide a mix of elevated performance parameters and straightforward integration. The APD has a strong linear gain figure, and is fully scalable – going from just ten to several hundred micrometre dimensions. The proprietary quenching circuit used in the SPAD results in a dead time of less than 15ns - whereby it supports high bandwidth. Also, its low dark count rate (<100 counts/s/µm<sup>2</sup>) means that it is far less sensitive to thermal noise. The high PDP of the SPAD assures that a far higher proportion of incident photons trigger an avalanche, and this is sustained across a comprehensive range of wavelengths (e.g. 40% at 400nm).


The APD and SPAD can be employed in a wide spectrum of different applications including proximity sensing, LiDAR, ToF, medical imaging and scientific research. Satisfying AEC-Q100 compliant, they are ideal for usage within automotive systems. Moreover, the low breakdown voltage (<20V) that has been accomplished aids their inclusion onto customer dies. As integral parts of the company's design kit, they are fully characterised, and can easily be joined with other modules highlighted in the XH018 process. Models for optical and electrical simulation, along with a specific application note, will assist designers to combine these devices into their circuitry within a short period. As well as being offered in a function block format, a quenching reference circuit that thoroughly demonstrates the abilities of the SPAD is also available.

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