VXS switch card for high speed high density data acquisition system

Detectors for particle physics research incorporate thousands of electrical sensors that are sensitive to charged particles and generate signals with fast risetimes and at high rates. Data processing requires detecting the time when signals from charged particle sensors cross thresholds with picosecond accuracy. The high speed high density data acquisition system that processes the data from the detector sensors is built around the VITA-41 VME64 switched serial (VXS) standard. The VITA-41 standard defines payload and switch slot module functions, and VITA-41 card enclosures can support up to 18 payload modules and 2 switch modules. The payload card (FADC) collects and processes data from 16 charged particle sensors with 10 or 12 bits resolutions at 250 MSPS sample rate and sends the results to the switch module for further processing. The system design targets a VITA-41 backplane that contains 2 switch slots. One switch slot receives data serially at an aggregate rate of up to 6 gigabits per second from up to 18 payload cards. The second switch slot will be used to distribute timing and synchronization signals to the payload modules. This paper describes the design and implementation of the VXS switch card.