Sep 25 – 29, 2006
Valencia, Spain
Europe/Zurich timezone

Signal Integrity Studies at Optical Multiplexer Board for TileCal System

Sep 27, 2006, 4:20 PM
1h 40m
Valencia, Spain

Valencia, Spain

IFIC – Instituto de Fisica Corpuscular Edificio Institutos de Investgación Apartado de Correos 22085 E-46071 València SPAIN


Jose Torres Pais (Dept. Ingenieria Electronica-Universidad de Valencia)


The Optical Multiplexer Board is a card included in the TileCal Data Acquisition System; it is designed to receive two optical fibers with same data from front-end boards and decided which has correct data. Inside this card we have different transmission lines that need to be studied; signal integrity problems such as signal delay, reflection, distortion and coupling should be analyzed. This paper presents the results of the signal integrity studies at the Optical Multiplexer Board for TileCal System.


TileCal is the hadronic calorimeter of the ATLAS experiments. It consists,
electronically speaking, of 10000 channels to be read each 25 ns. Data gathered
from these channels are digitized and transmitted to the data acquisition system
(DAQ) following the assertions of a three level trigger system.
In the acquisition chain, place is left for a system which has to perform pre-
processing and gathering on data coming out after a good first level trigger before
sending them to the second level. This system is called the Read Out Module (ROD).
Before the ROD we have a pre-ROD card, called Optical Multiplexed Board (OMB), able
to analyze two fibbers, both of then carrying the same data, to provide the correct
one to the ROD input.
The interest of this project was justified in February 2003, when a preliminary
study appeared. This proposal shown a solution for OMB based on exhaustive on-line
analysis of the data carried by both of the fibbers, using FPGAs for
Universidad de Valencia – IFIC (Spain) team showed the greater interest to deal
with this project, to make a first prototype to study technical viability. In
particular, the main goals are:
• Fibber optic switching to take advantage of redundancy
• Obtain real (production) costs
• Have a development platform (hw - sw)
• Try different alternatives for data error analysis (CRC, etc.)
In this paper we want to show the Signal Integrity Studies made to this card; OMB
is a high-speed digital design and Signal Integrity has become a critical issue.
The term Signal Integrity addresses two concerns in the electrical design aspects,
the timing and the quality of the signal. The goal of this Signal Integrity
analysis is to ensure reliable high-speed data transmission.
We can divide the studies in two parts, the pre-layout (without which prototypes
may never leave the bench) and the post-layout (without which products may fail in
the field).
In the pre-layout stage, Signal Integrity analysis they were used to select
technology for I/Os, clock distributions, chip package types, component types,
board stackups, pin assignments, net topologies, and termination strategies.
With an initial physical layout, post-layout Signal Integrity analysis verified
reflection noise, ringing, crosstalk and ground bounce.
The results were correct and allowed the accomplishment of the card that at the
present time is in operation at CERN.

Primary author

Jose Torres Pais (Dept. Ingenieria Electronica-Universidad de Valencia)


Mr Alberto Valero Biot (IFIC-Valencia) Dr Antonio Ferrer Soria (IFIC-Valencia) Dr Antonio Munar (IFIC-Valencia) Ms Arantxa Ruiz Martinez (IFIC-Valencia) Ms Belen Salvachua Ferrando (IFIC-Valencia) Mr Carlos Solans Sanchez (IFIC-Valencia) Mr Cristobal Cuenca Almenar (IFIC-Valencia) Dr Emilio Higon Rodriguez (IFIC-Valencia) Dr Enrique Sanchis Peris (Dept. Ingenieria Electronica-Universidad de Valencia) Mr Esteban Fullana Torregrosa (IFIC-Valencia) Dr Jesus Soret Medel (Dept. Ingenieria Electronica-Universidad de Valencia) Mr Joaquin Poveda Torres (IFIC-Valencia) Mr Jose Castelo Curras (IFIC-Valencia) Dr Juan Antonio Valls Ferrer (IFIC-Valencia) Dr Vicente Gonzalez Millan (Dept. Ingenieria Electronica-Universidad de Valencia) Dr Victoria Castillo Gimenez (IFIC-Valencia)

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