CASA: a Readout ASIC for Gas Detectors with Self-Amplification

A readout ASIC has been designed for gas detectors with self-amplification such as GEM and RPC. It provides amplification and CR-(RC)(4) shaping of the detector signals and buffers them to the free running ADCs at similar to 10MSPS. The charge gain can be adjusted from 1mV/fC to 28mV/fC and the shaping time can be adjusted from 25ns to 100ns. The programmability of the gain in such wide range and the shaping time is very convenient for studying detector performance and also expands the application range of the chip. The ENC increases as charge gain decreases below 10mV/fC because the noise from the shaper becomes significant. The chip is designed in Chartered 0.35 mu m 2P4M CMOS process. Detailed circuit description and preliminary test results will be shown below.