Nowadays, there is a steadily growing interest in single photon detectors driven by the need for ultimate sensitivity in various scientific and industrial applications. In particular, the use of fluorescence lifetime spectroscopy increased markedly in recent years and the Time Correlated Single Photon Counting (TCSPC) technique is currently used for directly measuring fluorescence decays. The evolution of TCSPC applications caused a growing demand for TCSPC multichannel systems able to achieve very high performance (both for the electronics and the detector) with even thousands of channels in parallel. However, to comply both specifications at the same time is still an open challenge. Custom-technology Single Photon Avalanche Diodes (SPADs) allow to reach the best performance for the detector but the designer is not allowed to integrated the electronics with the sensor and he/she is, therefore, forced to employ two different chips. Moreover, in order to exploit custom SPADs in a TCSPC system, two front-end circuits are required: the quenching circuit that makes the device sensitive again after the collection of each single photon and the pick-up circuit that extracts the information about the photon arrival time with a picoseconds precision. In this scenario, each SPAD requires two connections towards the front-end electronics thus leading to interconnection issues as the number of channel increases. The aim of this work is to design a fully-integrated front-end circuit able to provide both quenching/reset and timing capabilities. This so-called Time-Resolving Active Quenching Circuit (TR-AQC) should provide the same performance achieved with two separate circuits but requiring a single connection toward the SPAD in order to minimize the interconnection issue. To this aim, the designed TR-AQC is composed of two main parts: a highprecision Trans-impedance amplifier, featuring an input impedance as low as 40 and a bandwidth as large as 360MHz to promptly collect the avalanche current thus minimizing the timing jitter, and a fast active quenching circuit with a completely revised quenching logic aiming at the minimization of the quenching delay, an aspect that is crucial to minimize the afterpulsing probability.
Negli ultimi anni, un forte interesse verso i rivelatori a singolo fotone è stato guidato dalla necessità di altissime prestazioni in molteplici applicazioni scientifiche ed industriali. Nello specifico, la misura dei tempi di vita di fluorescenza si è diffusa in modo significativo e la tecnica Time Correlated Single Photon Counting (TCSPC) è oggigiorno usata per la misura dei decadimenti di fluorescenza. L’evoluzione delle applicazioni TCSPC ha portato una continua richiesta di sistemi multicanale in grado di ottenere altissime prestazioni (sia per il dispositivo sia per l’elettronica) con migliaia di canali in parallelo. Tuttavia, soddisfare entrambe le specifiche contemporaneamente è ancora oggi una sfida aperta. I Single Photon Avalanche Diodes (SPADs) in tecnologia custom permettono di ottenere le migliori performance per il rivelatore ma il processo di fabbricazione non consente al designer di integrare l’elettronica con il sensore ed egli è dunque costretto ad utilizzare due chip differenti. Per di più, per utilizzare uno SPAD custom in un sistema TCSPC, due circuiti di front-end sono necessari: il circuito di quenching che rende il dispositivo nuovamente sensibile dopo ogni rivelazione di singoli fotoni e il circuito di prelievo che estrae l’informazione sul tempo di arrivo del fotone con una precisione delle decine di picosecondi . In questo scenario, ogni SPAD richiede due collegamenti con l’elettronica di frontend e ciò porta a problemi di interconnessioni all’aumentare del numero di canali. L’obiettivo di questo lavoro è progettare un circuito integrato di front-end in grado di fornire sia la funzionalità di quenching/reset sia di timing. Il Time-Resolving Active Quenching Circuit (TR-AQC) dovrebbe garantire le stesse performance raggiunte dai due circuiti separati ma richiedendo una singola connessione verso lo SPAD al fine di minimizzare il problema delle interconnessioni. A questo proposito, il TR-AQC progettato è composto da due parti principali: un amplificatore a trans-impedenza ad alta precisione, caratterizzato da una bassa impedenza di ingresso (40 ) ed un’ampia banda (360MHz) per prelevare rapidamente la corrente di valanga minimizzando così il jitter, e un veloce circuito di quenching attivo (AQC) con una logica di quenching completamente rivisitata al fine di minimizzare il ritardo di quenching, un parametro cruciale per minimizzare la probabilità di afterpulsing.
Design of a time-resolving active quenching circuit in 150nm CMOS technology for custom single photon avalanche diodes
PINSERO, MARCO
2018/2019
Abstract
Nowadays, there is a steadily growing interest in single photon detectors driven by the need for ultimate sensitivity in various scientific and industrial applications. In particular, the use of fluorescence lifetime spectroscopy increased markedly in recent years and the Time Correlated Single Photon Counting (TCSPC) technique is currently used for directly measuring fluorescence decays. The evolution of TCSPC applications caused a growing demand for TCSPC multichannel systems able to achieve very high performance (both for the electronics and the detector) with even thousands of channels in parallel. However, to comply both specifications at the same time is still an open challenge. Custom-technology Single Photon Avalanche Diodes (SPADs) allow to reach the best performance for the detector but the designer is not allowed to integrated the electronics with the sensor and he/she is, therefore, forced to employ two different chips. Moreover, in order to exploit custom SPADs in a TCSPC system, two front-end circuits are required: the quenching circuit that makes the device sensitive again after the collection of each single photon and the pick-up circuit that extracts the information about the photon arrival time with a picoseconds precision. In this scenario, each SPAD requires two connections towards the front-end electronics thus leading to interconnection issues as the number of channel increases. The aim of this work is to design a fully-integrated front-end circuit able to provide both quenching/reset and timing capabilities. This so-called Time-Resolving Active Quenching Circuit (TR-AQC) should provide the same performance achieved with two separate circuits but requiring a single connection toward the SPAD in order to minimize the interconnection issue. To this aim, the designed TR-AQC is composed of two main parts: a highprecision Trans-impedance amplifier, featuring an input impedance as low as 40 and a bandwidth as large as 360MHz to promptly collect the avalanche current thus minimizing the timing jitter, and a fast active quenching circuit with a completely revised quenching logic aiming at the minimization of the quenching delay, an aspect that is crucial to minimize the afterpulsing probability.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/154383