ICS843002I-41 Datasheet, PDF (13/21 Pages) Integrated Circuit Systems – 700MHz, FEMTOCLOCKS-TM VCXO BASED SONET/SDH JITTER ATTENUATOR

Integrated
Circuit
Systems, Inc.
PRELIMINARY
ICS843002I-41
700MHZ, FEMTOCLOCKS™ VCXO BASED
SONET/SDH JITTER ATTENUATOR
POWER SUPPLY FILTERING TECHNIQUES
As in any high speed analog circuitry, the power supply pins
are vulnerable to random noise. The ICS843002I-41 provides
separate power supplies to isolate any high switching
noise from the outputs to the internal PLL. V_CC, V_CCA, and V_{CCO_X}
should be individually connected to the power supply
plane through vias, and bypass capacitors should be
used for each pin. To achieve optimum jitter performance,
power supply isolation is required. Figure 2 illustrates how
a 10Ω resistor along with a 10μF and a .01μF bypass
capacitor should be connected to each V_CCA pin.
V_CC
V
CCA
3.3V
.01μF 10 Ω
.01μF
10μF
FIGURE 2. POWER SUPPLY FILTERING
TERMINATION FOR 2.5V LVPECL OUTPUT
Figure 3A and Figure 3B show examples of termination for 2.5V
LVPECL driver. These terminations are equivalent to terminat-
ing
50Ω
to
V
CC
-
2V.
For
V
CC
=
2.5V,
the
V
CC
-
2V
is
very
close
to
ground level. The R3 in Figure 3B can be eliminated and the
termination is shown in Figure 3C.
VC C=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
VC C=2. 5V
Zo = 50 Ohm
Zo = 50 Ohm
2,5V LVPECL
Driv er
2.5V
+
-
R1
R2
50
50
R3
18
FIGURE 3A. 2.5V LVPECL DRIVER TERMINATION EXAMPLE
FIGURE 3B. 2.5V LVPECL DRIVER TERMINATION EXAMPLE
VC C=2. 5V
Zo = 50 Ohm
Zo = 50 Ohm
2,5V LVPECL
Driv er
2.5V
+
-
R1
R2
50
50
FIGURE 3C. 2.5V LVPECL TERMINATION EXAMPLE
843002AKI-41
www.icst.com/products/hiperclocks.html
13
REV. A JUNE 1, 2005