Design and test of prototype boards for the L1 calorimeter trigger upgrade at the D0 experiment

This paper presents the development and test of some of the electronic boards that have been designed for the upgrade of the L1 calorimeter trigger at the D0 experiment. The analog to digital converter and filter board (ADF) digitizes 32 calorimeter channels, applies digital filtering, and sends data to the next processing stage via 2 Gbit/s links. The board is designed for sustained operation at 7.57 MHz with an end-to-end latency of less than ~1 mus. In order to test the high-speed output links of the ADF board, we made a tester that comprises a custom made channel link receiver card. To connect a prototype ADF board to the D0 detector without disturbing the existing trigger system, we designed a splitter board that duplicates the analog signals from 8 calorimeter channels. The serial command link distribution card (SCLD) is designed to accurately distribute synchronization signals to the 80 ADF boards of the final system. We made single channel versions of the ADF and SCLD boards. These cards run in a simple desktop PC environment and are helpful for tests and collaborative work. We describe the hardware, firmware and software aspects of the various developments and show the operation of the different boards. We present performance measurements made on the prototype ADF board, and explain how we defined the production model of this board.