EK1HMC7044LP10B User Guide

UG-826

Rev. 0 | Page 9 of 10

The output termination selection shown in Figure 21 is accessed

by clicking any of the drop-down lists under DRIVER in the

OUTPUTS

tab (see Figure 19). It is important to power down

unused outputs on the evaluation board because they can be a

major source of unwanted spurs.

Even numbered outputs (CLKOUTx/CLKOUTx pins) are ac-

coupled with 150 Ω to ground for each leg on the board by

default. Odd numbered outputs (SCLKOUTx/SCLKOUTx pins)

are ac-coupled with 100 Ω to VCC internally; no termination

resistors are on the board by default. This termination scheme is

ideal for CML drivers. However, this scheme degrades the CMOS

driver performance. Improved CMOS driver performance is

achieved by removing the termination resistors. For LVDS drivers,

differential 100 Ω resistor must be populated on the board.

Figure 21. Output Termination Selection