Datasheet

UG-076 Evaluation Board User Guide
Rev. 0 | Page 12 of 16
OUTPUT DRIVER WINDOW
OUT 0 through OUT8 are ac-coupled with 200  pull-down
resistors on each output. This termination scheme is ideal for
LVPECL drivers. However, this scheme degrades the CMOS
driver performance. Improved CMOS driver performance is
achieved by removing the 200  pull-down resistors.
The output driver window shown in Figure 22 is accessed by
clicking any of the numbered triangular output driver symbols
on the right side of the main window (see Figure 21).
08746-026
OUT9 though OUT11 have no termination resistors, and are
ideally configured for CMOS operation. If you want to use these
drivers in LVPECL mode, pull-down resistors must be added to
the board. If you want to put 50  termination at the SMA
connectors of OUT9 through OUT11, add series decoupling
capacitors so that the termination on OUT9 through OUT11 is
identical to OUT0 through OUT8.
Figure 21. Driver Symbol
08746-017
DEBUG WINDOW
The Debug window shown in Figure 23 is accessed by clicking
the Debug option from the View menu.
The Serial I/O section of this window is a convenient way to
read and write registers directly.
08746-018
Figure 22. Output Driver Window
It is important to power down unused outputs on the evaluation
board because they can be a major source of unwanted spurs.
LVPECL and CMOS outputs have different termination require-
ments, and OUT9 through OUT11 have been terminated
differently from OUT0 through OUT8.
Figure 23. Debug Window