ICS843034-01 Datasheet, PDF (17/22 Pages) Integrated Circuit Systems – FEMTOCLOCKS™ MULTI-RATE LVPECL FREQUENCY SYNTHESIZER

Integrated
Circuit
Systems, Inc.
PRELIMINARY
ICS843034-01
FEMTOCLOCKS™
MULTI-RATE LVPECL FREQUENCY SYNTHESIZER
TERMINATION FOR 2.5V LVPECL OUTPUT
Figure 7A and Figure 7B show examples of termination for
2.5V LVPECL driver. These terminations are equivalent to ter-
minating 50Ω to V_CC - 2V. For V_CC = 2.5V, the V_CC - 2V is very
close to ground level. The R3 in Figure 7B can be eliminated
and the termination is shown in Figure 7C.
VC C O=2. 5V
Zo = 50 Ohm
Zo = 50 Ohm
2,5V LVPECL
Driv er
2.5V
R1
R3
250
250
2.5V
+
-
R2
62.5
R4
62.5
VCCO=2.5V
Zo = 50 Ohm
Zo = 50 Ohm
2,5V LVPECL
Driv er
2.5V
+
-
R1
R2
50
50
R3
18
FIGURE 7A. 2.5V LVPECL DRIVER TERMINATION EXAMPLE
FIGURE 7B. 2.5V LVPECL DRIVER TERMINATION EXAMPLE
VCCO=2.5V
Zo = 50 Ohm
Zo = 50 Ohm
2,5V LVPECL
Driv er
2.5V
+
-
R1
R2
50
50
FIGURE 7C. 2.5V LVPECL TERMINATION EXAMPLE
843034AY-01
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REV. C NOVEMBER 28, 2005