Digital calorimetry relies on a highly granular detector where the cell size is sufficiently small so that only a single particle in a shower enters each cell within a single readout cycle. The DECAL sensor, a depleted monolithic active pixel sensor (DMAPS), has been proposed as a possible technology for future digital calorimeters. A DECAL sensor prototype has been designed and fabricated in the TowerJazz 180 nm CMOS imaging process, using high resistivity 18 μm epitaxial layer. The prototype has a pixel matrix of 64x64 pixels with a pitch of 55x55 μm, and reads out using fast logic at 40 MHz. Each pixel contains four collection electrodes, trimming logic, pre-amplifier, shaper and discriminator with digital output. The pixel configuration logic provides a 5 bit calibration DAC and a mask flag. It can be reconfigured to function as either a strip sensor, for particle tracking, or a pad sensor, counting the number of pixels above threshold for digital calorimetry. The sensor is mounted on a custom designed PCB and read out using an Ethernet based readout system.
The talk will present results of chip characterisation, including digital summing logic, analogue pixel performance and threshold scans under laser illumination. Measurements will be compared to expected results from simulation.