Large-Area Picosecond Photo-Detectors
We have proposed using micro-channel plates (MCP-PMTs) with a novel equal-time anode and with capacitive-return-path coupling to measure the time-of-flight of relativistic particles with 1 psec resolution. The proposed readout electronics for each MCP-PMT unit consists of 4 identical front-end ASICs and one DAQ ASIC that digitizes the front-end outputs, distributes the system clock, and handles all digital traffic. The front-end ASIC chip is a `time stretcher', converting the difference in times between start and stop pulses into a digital pulse with width proportional to the input time interval but stretched by a factor of 200. We are designing in the IBM 0.13um SiGe BiCMOS 8HP process, The circuitry includes a limiting amplifier and a constant-fraction discriminator. The DAQ chip then digitizes the stretched time interval. The preliminary design and detailed simulations of the front-end ASIC chip will be presented.
UChicago LAPPD Site
Faculty: Henry Frisch