# A Novel Electronic Interface for Micromachined Si-Based Photomultipliers

^{*}

## Abstract

**:**

## 1. Introduction

## 2. CMOS Integrable Solution

^{+}(if both the currents are pointing inwards or outwards) or a VCII

^{−}(if currents are pointing in opposite directions). The parameters r

_{y}, L

_{y}, r

_{x}, C

_{x}, r

_{z}and L

_{z}are the parasitic impedances related to each terminal. They should ideally be equal to zero except for r

_{x}, which should be equal to infinity. Given these considerations, we can simplify Equation (1) to Equation (2):

^{+}building block used in the SiPM interface is shown in Figure 2. The transistor dimensions are reported in the same schematic. Its design was created using a standard Austria micro systems (AMS) 350 nm CMOS technology with a supply voltage of ±1.65 V. As highlighted, it consists of a current buffer and a voltage buffer. In particular, M

_{c}

_{4}, M

_{in}

_{1,2}, and M

_{c}

_{1,2}employ a gain boosted common gate amplifier, which together with the current mirror M

_{c}

_{3,4}, conveys the Y input current to the X node, implementing the I

_{x}= βI

_{y}relationship. On the other hand, M

_{v}

_{2,3}forms a flipped-voltage-follower buffer, mirroring the X input voltage (suitably shifted by M

_{v1}) to the Z node (V

_{z}= αV

_{x}).

_{p_N}was placed to account for the total single-core parasitics. The SiPM was then obtained as an array of N repetitions of this basic structure. A switch (see Figure 5b) was also added in series with the SiPM in order to be able to decide the exact time of an occurrence. The actual interface is shown in Figure 5b. It consists of a single VCII performing as a transimpedance amplifier (TIA). The photomultiplier (or array of photomultipliers) output is connected to the Y terminal. By analyzing the X terminal and using the first relationship of Equation (1), we can write:

_{z}= αV

_{x}= V

_{out}we can conclude that:

## 3. Hybrid Solution, Simulations and Test

## 4. Conclusions

## Author Contributions

## Funding

## Acknowledgments

## Conflicts of Interest

## References

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**Figure 1.**Second-generation voltage conveyor (VCII) equivalent representation. Dashed boxes highlight the parasitic components at each terminal.

**Figure 5.**(

**a**) Silicon photomultipliers (SiPM) equivalent model; (

**b**) the proposed VCII-based SiPM array interface where C

_{par_i}= Σ C

_{p_N}.

**Figure 6.**(

**a**) Transimpedance amplifier (TIA) transfer function at different gain levels; (

**b**) TIA output equivalent noise at different noise levels.

**Figure 7.**Time domain response of the interface to a train of SiPM current pulses at different amplitude levels.

**Figure 8.**(

**a**) Time domain output voltage for different parasitic capacitances, simulating the interface to be used with an array of SiPMs; (

**b**) interface output voltage variations at different temperatures; (

**c**) interface output voltage for three different capacitive loads connected to the VCII Z node; (

**d**) interface output voltage for ±5% supply voltage variations.

**Figure 10.**Simulation results on the prototype board: input current and output voltage of the discrete interface.

**Figure 11.**(

**a**) Final prototype board; test benches: (

**b**) for time domain measurements; (

**c**) for frequency domain measurements.

**Figure 12.**Multi-pulse input signal (continuous line) and measured output response (dotted line) of the discrete interface.

**Figure 13.**Multi-pulse variable input signal (continuous line) and measured output response (dotted line) of the discrete interface.

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**MDPI and ACS Style**

Pantoli, L.; Barile, G.; Leoni, A.; Muttillo, M.; Stornelli, V.
A Novel Electronic Interface for Micromachined Si-Based Photomultipliers. *Micromachines* **2018**, *9*, 507.
https://doi.org/10.3390/mi9100507

**AMA Style**

Pantoli L, Barile G, Leoni A, Muttillo M, Stornelli V.
A Novel Electronic Interface for Micromachined Si-Based Photomultipliers. *Micromachines*. 2018; 9(10):507.
https://doi.org/10.3390/mi9100507

**Chicago/Turabian Style**

Pantoli, Leonardo, Gianluca Barile, Alfiero Leoni, Mirco Muttillo, and Vincenzo Stornelli.
2018. "A Novel Electronic Interface for Micromachined Si-Based Photomultipliers" *Micromachines* 9, no. 10: 507.
https://doi.org/10.3390/mi9100507