V
*
CC
Transceiver Power Supply Bypass
and Loop Filter Capacitors
V
CC
If desired, bypass capacitors may
be used on the power supply pins
of the HDMP-1638G. All bypass
chip capacitors are 0.1 μF. The
C
PLLR
V
_RXA and V _TXA pins are
CC
CC
RXCAP0
GND_TXHS
the analog power supply pins for
the PLL sections. The supply into
these pins should be clean with
minimum noise. Use of capacitors
as shown in Figure 12 is
mandatory for these pins. The PLL
loop filter capacitors and their pin
locations are also shown on Figure
12. Notice that only two capacitors
GND_RXTTL
V
V
_RXTTL
_RXTTL
V
CC
CC
HDMP-1638G
TOP VIEW
CC
are required; C
for the trans-
PLLT
mitter and C
for the receiver.
PLLR
GND_TXTTL
GND_TXA
Nominal capacitance is 0.1 μF. The
maximum voltage across the
capacitors is on the order of 1 volt,
so the capacitor can be a low
voltage type and physically small.
The PLL capacitors are to be
placed physically close to the
appropriate pins on the HDMP-
1638G. Keeping the lines short will
prevent them from picking up any
stray noise from surrounding lines
or components.
TXCAP1
GND_RXTTL
C
V
PLL
CC
V
*
CC
* SUPPLY VOLTAGE INTO V _RXA AND V _TXA SHOULD BE FROM A LOW NOISE
CC CC
SOURCE. ALL BYPASS CAPACITORS AND PLL FILTER CAPACITORS ARE 0.1 µF.
Figure 12. Power supply bypass.
Start Up Procedure:
The transceiver startup procedure(s) and the following conditions:
V
= +3.3 V 5% and REFCLK = 125 MHz 100 ppm.
CC
After the above conditions have been met, apply valid data using a
balanced code such as 8B/Figure 13: Mechanical Dimensions of
HDMP-1638G.
15
PMC-Sierra, Inc. - Not Recommended for New Designs
PMC [ PMC-SIERRA, INC ]
