ICS84314-02 Datasheet, PDF (11/17 Pages) Integrated Circuit Systems – 700MHZ, CRYSTAL-TO-3.3V/2.5V LVPECL FREQUENCY SYNTHESIZER W/FANOUT BUFFER

Integrated
Circuit
Systems, Inc.
PRELIMINARY
ICS84314-02
700MHZ, CRYSTAL-TO-3.3V/2.5V LVPECL
FREQUENCY SYNTHESIZER W/FANOUT BUFFER
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 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 5A can be eliminated
and the termination is shown in Figure 5C.
VCCO=2.5V
Zo = 50 Ohm
Zo = 50 Ohm
2,5V LVPECL
Driv er
2.5V
+
-
R1
R2
50
50
R3
18
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
FIGURE 5A. 2.5V LVPECL DRIVER TERMINATION EXAMPLE
FIGURE 5B. 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 5C. 2.5V LVPECL TERMINATION EXAMPLE
84314AY-02
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11
REV. B NOVEMBER 17, 2005