Radiation hard active pixel sensor with 25μm × 50μm pixel size designed for capacitive readout with RD53 ASIC

A new concept for a capacitively coupled particle detector (CCPD) is described. Sensor and readout chips are attached using a small number of large bumps. A sensor chip for such a CCPD has been designed and tested. The sensor chip is based on the HVCMOS structure. Deep n-well is used as the charge collecting electrode. To allow strong amplification, which is necessary for chip to chip signal transmission, a novel CMOS based comparator with rail to rail output swing has been implemented in each pixel. The pixel outputs are connected to transmitting electrodes implemented in the top metal layer of the sensor chip. Using special address encoding a group of 16 pixels is connected to 8 transmitting electrodes. The pixel size is 25μm × 50μm and the transmitting electrode pitch is 50μm × 50μm. Therefore a standard HL-LHC readout chip developed by RD53 collaboration can be used for readout of the sensor.