SIPHRA 16-Channel Silicon Photomultiplier Readout ASIC

SIPHRA is an integrated circuit (IC) for the readout of photon detectors, such as photomultiplier tubes (PMTs), silicon photomultipliers (SiPMs), and multi-pixel photon counters (MPPCs). The IC has 16 input channels and one summing channel. Each channel can be used for pulse height spectroscopy and timing. The summing channel is important for the readout of detector arrays with monolithic scintillators. The programmable shaping time of 200 ns, 400 ns, 800 ns, or 1600 ns allows for pulse-height spectroscopy using scintillators with different light emission properties. The current mode input stage (CMIS) is designed for large negative charge (-16 nC, -8 nC, -4 nC, and -0.4 nC), depending on the programmable attenuation, and it accommodates large capacitive load (several nF) and large leakage current (up to -100 μA from dark counts). Alternatively, the CMIS can be by-passed to allow for positive charge depending on programmable gain (+40 pC, +4 pC, +0.4 pC). The IC contains one 12-bit analog-to-digital converter (ADC) that allows for digitization of the pulseheights from all channels, including the summing channel at a sampling rate of 50 ksps. Every channel output is available for external use and provides either the analog or a digital trigger/timing pulse with fixed width or time-over-threshold. The programmable channel output facilitates many applications, such as external waveform sampling and digitization, pulse height and time spectroscopy, pulse counting, and triggering. The IC operates at 3.3-V supply voltage and dissipates about 15 mW without CMIS and 30 mW with CMIS active. To save power, any channel or function can be powered down. The ASIC has a serial peripheral interface (SPI) for programming its register settings and for slow ADC data readout; faster readout with up to 1 Mbit/s is possible via a serial data transmission line.