GRAPH -- An readout ASIC for large MCP based detectors

TL;DR

The paper introduces GRAPH, a programmable 16-channel ASIC designed for large MCP-based photon detectors, featuring novel hybrid sampling architecture and efficient event processing for high-speed waveform recording.

Contribution

It presents a new mixed-signal ASIC with hybrid sampling architecture and advanced event readout capabilities for large MCP detectors.

Findings

Achieves adjustable sampling frequency up to 125 MHz.

Records 2048 samples per channel with 12-bit digital resolution.

Reduces dead time with optimized region of interest sampling.

Abstract

We present a programmable 16 channel, mixed signal, low power readout ASIC, having the project historically named Gigasample Recorder of Analog waveforms from a PHotodetector (GRAPH). It is designed to read large aperture single photon imaging detectors using micro channel plates for charge multiplication, and measuring the detector's response on crossed strips anodes to extrapolate the incoming photon position. Each channel consists of a fast, low power and low noise charge sensitive amplifier, which provides a myriad of coarse and fine programmable options for gain and shaping settings. Further, the amplified signal is recorded using, to our knowledge novel, the Hybrid Universal sampLing Architecture (HULA), a mixed signal double buffer memory, that enables concurrent waveform recording, and selected event digitized data extraction. The sampling frequency is freely adjustable between few~kHz up to 125~MHz, while the chip's internal digital memory holds a history 2048 samples for each channel, with a digital headroom of 12 bits. An optimized region of interest sample-read algorithm allows to extract the information just around the event pulse peak, while selecting the next event, thus substantially reducing the operational dead time. The chip is designed in 130~$n$m TSMC CMOS technology, and its power consumption is around 47~$m$W per channel.