A waveform sampling front-end ASIC for readout of GSO/APD with DOI information

A new 9-channel Waveform Sampling Front-End (WSFE) Application Specific Integrated Circuit (ASIC) for readout of avalanche photodiodes (APD) has been developed based on two prototypes. Each channel of the chip consists of a preamplifier, a variable gain amplifier (VGA) and a fast analog to digital converter (ADC) to digitize signals from the APD. Such a scheme allows individual readouts of small pixellated APD for better spatial resolution and counting rate over conventional light sharing or charge division types while enabling depth-of-interaction (DOI) decoding. Each component has shown satisfactory performance and this chip has been used to readout GSO-APD detector to study its DOI capabilities.