
IDT / ICS 2.5V LVPECL FREQUENCY SYNTHESIZER
11
ICS843001AK-40 REV. A OCTOBER 10, 2007
ICS843001-40
FEMTOCLOCKS CRYSTAL-TO-2.5V LVPECL FREQUENCY SYNTHESIZER
TERMINATION FOR 2.5V LVPECL OUTPUT
Figure 5A and Figure 5B show examples of termination for 2.5V
LVPECL driver. These terminations are equivalent to terminating
50
Ω to V
CC
– 2V. For V
CCO
= 2.5V, the V
CCO
– 2V is very close to
ground level. The R3 in Figure 5B can be eliminated and the
termination is shown in Figure 5C.
FIGURE 5C. 2.5V LVPECL TERMINATION EXAMPLE
R2
50
Zo = 50 Ohm
VCCO=2.5V
R1
50
Zo = 50 Ohm
+
-
2.5V
2,5V LVPECL
Driv er
FIGURE 5B. 2.5V LVPECL DRIVER TERMINATION EXAMPLE
VCCO=2.5V
R1
50
R2
50
Zo = 50 Ohm
R3
18
2,5V LVPECL
Driv er
Zo = 50 Ohm
+
-
2.5V
FIGURE 5A. 2.5V LVPECL DRIVER TERMINATION EXAMPLE
R2
62.5
2.5V
2,5V LVPECL
Driv er
R3
250
Zo = 50 Ohm
R4
62.5
2.5V
+
-
R1
250
VCCO=2.5V