ICS843207-350 Datasheet, PDF (8/16 Pages) Integrated Device Technology – FEMTOCLOCKS™ CRYSTAL-TO-LVPECL 350MHZ FREQUENCY MARGINING SYNTHESIZER

ICS843207-350
FEMTOCLOCKS™ CRYSTAL-TO-LVPECL 350MHZ FREQUENCY MARGINING SYNTHESIZER
APPLICATION INFORMATION
PRELIMINARY
POWER SUPPLY FILTERING TECHNIQUES
As in any high speed analog circuitry, the power supply pins are
vulnerable to random noise. To achieve optimum jitter perfor-
mance, power supply isolation is required. The ICS843207-350
provides separate power supplies to isolate any high switching
noise from the outputs to the internal PLL. V_CC, V_CCA and V_CCO
should be individually connected to the power supply plane
through vias, and 0.01µF bypass capacitors should be used
for each pin. Figure 1 illustrates this for a generic V_CC pin and
also shows that V_CCA requires that an additional 10Ω resistor
along with a 10µF bypass capacitor be connected to the V_CCA
pin.
3.3V
V_CC
.01μF 10Ω
V_CCA
.01μF
10μF
FIGURE 1. POWER SUPPLY FILTERING
CRYSTAL INPUT INTERFACE
The ICS843207-350 has been characterized with 18pF
parallel resonant crystals. The capacitor values shown in
Figure 2 below were determined using a 14MHz, 18pF parallel
resonant crystal and were chosen to minimize the ppm error.
X1
18pF Parallel Crystal
XTAL_OUT
C1
27p
XTAL_IN
C2
27p
FIGURE 2. CRYSTAL INPUt INTERFACE
IDT^™ / ICS^™ LVPECL FREQUENCY MARGINING SYNTHESIZER
8
ICS843207CY-350 REV. A DECEMBER 3, 2007