Virtex-4 RocketIO MGT User Guide www.xilinx.com 235UG076 (v4.1) November 2, 2008RChapter 9Methodology OverviewIntroductionXilinx, in partnership with Dr. Howard Johnson, has developed a two-part DVD tutorialon signal integrity techniques and loss budgeting for RocketIO transceivers. [Ref 2] TheseDVDs cover in more detail much of the material in Chapter 9 through Chapter 12 of thisUser Guide.Figure 9-1 shows a typical physical interconnect topology between two RocketIO multi-gigabit transceivers (MGTs). Any physical link connecting two point-to-point high-speedserial transceivers is defined as a channel. A channel begins at the die solder bumps of thetransmitter and ends at the die solder bumps of the receiver.In Figure 9-1, the channel consists of the FPGA package, transmission lines, connectors andtransitions.Transitions are defined as any section along a multi-gigabit channel where the signal mustgo from a transmission line to a three-dimensional structure or vice-versa. Vias,connectors, and coupling capacitors are examples of these structures.While a more comprehensive list of transitions is discussed in Chapter 11, “Design ofTransitions,” some common transitions are:• Ball grid array (BGA) to PCB microstrip• Microstrip to stripline vias• DC blocking capacitors• Connectors• Bends and turns in a traceFor optimal performance, the following must be minimized in a given channel:• Signal attenuation due to losses in the transmission mediumFigure 9-1: Two RocketIO MGTs InterconnectedTXPackageBGA Break-OutStriplines or MicrostripsTransition ConnectorConnector pinsDaughter Card Backplane Other halfmirrored to RXTXPTXNug072_c3_01_030106
