A low noise and low power cryogenic amplifier for single photoelectron sensitivity with large arrays of SiPMs

Abstract

A: This paper presents a low noise amplifier for large arrays of silicon photomultipliers (SiPMs) operated in cryogenic environments, especially liquid argon (87 K) and liquid nitrogen (77 K). The goal is for one amplifier to read out a total photosensitive surface of tens of cm 2 while retaining the capability to resolve single photoelectron signals. Due to the large capacitance of SiPMs, typically a few nF per cm 2 , the main contributor to noise is the series (voltage) component. A silicon-germanium heterojunction bipolar transistor (HBT) was selected as the input device of the cryogenic amplifier, followed by a fully differential operational amplifier, operated in an unconventional feedback configuration. The input referred voltage noise of the circuit at 77 K is just below 0.4 nV/ √ Hz white (above 100 kHz) and 1 nV/ √ Hz at 10 kHz. The value of the base spreading resistance of the HBT at 77 K was determined from noise measurements at different bias currents. Power consumption of the full circuit is about 2.5 mW. The design gives the flexibility to optimally compensate the feedback loop for different values of the input capacitance, and obtain a gain-bandwidth product in the GHz range. The signal-to-noise ratio obtained in reading out SiPMs is discussed for the case of a 300 kHz low pass filter and compared with the upper limit that would derive from applying optimum filtering algorithms. K: Front-end electronics for detector readout, analogue electronic circuits, Photon detectors for UV, visible and IR photons (solid-state), Noble liquid detectors (scintillation, ionization, double-phase).

Performance of Hamamatsu VUV4 SiPMs for detecting liquid argon scintillation

“…Compensating for this by operating the SiPMs at high overvoltages to achieve high gains may degrade the single photoelectron charge resolution through increased afterpulsing and crosstalk. Optimal performance can be obtained by pairing SiPMs with low-noise amplifiers to achieve O (1 × 10 7 ) gain at relatively low overvoltages that do not lead to excessive crosstalk and afterpulsing [20][21][22], yet enable efficient detection of SPE pulses at the mV-scale.…”

Cryogenic characterization of Hamamatsu HWB MPPCs for the DUNE photon detection system

“…The box helps in shielding the electromagnetic noise picked up by the amplifier and also the Cherenkov light produced by cosmic rays inside the volume of the dewar that would spoil the intrinsic Dark Count Rate (DCR) measurement. The amplifier used was the one developed at the Milano-Bicocca University [6]. Few setups used a similar amplifier with analogous characteristics.…”

“…An undershoot is seen in the average signals due to the AC coupling at the outputs of the cold amplifier. The design of the cold amplifier is described in deeper detail in [6] and [12]. The same amplifier is used to test, in LN2, the ganging of 48 SiPMs of the four candidate Hamamatsu.…”

Cryogenic front-end amplifier design for large SiPM arrays in the DUNE FD1-HD photon detection system

“…Figure 4 shows the schematic of the cold amplifier. The design is the evolution of an already published work [9]. It operates with a single power supply 𝑉 𝐶𝐶 = 3.3 V. The supply current returns on 𝑉 𝐸 𝐸 = 0 V. Both supplies are filtered to ground with 100 nF caramic capacitors, not shown in the schematic.…”