V
CC
*
V
CC
C
PLLR
GND_TXTTL
RXCAP0
GND_RXTTL
V
CC
_TXTTL
V
CC
_RXTTL
V
CC
TOP VIEW
V
CC
_TXTTL
GND_TXTTL
GND_TXA
TXCAP0
V
CC
_TXA
V
CC
_RX
V
CC
_TX
GND
V
CC
_RXTTL
GND_RXTTL
V
CC
_RX
V
CC
_RXTTL
TXCAP1
C
PLLT
GND_RXTTL
power supply pins of the
HDMP-1636/46 as shown on the
schematic of Figure 12. All
bypass chip capacitors are
0.1
µF.
The V
CC
_RXA and
V
CC
_TXA pins are the analog
power supply pins for the PLL
sections. The voltage into these
pins should be clean with
minimum noise. The PLL loop
filter capacitors and their pin
locations are also shown on
Figure 12. Notice that only two
capacitors are required: C
PLLT
for
the transmitter and C
PLLR
for the
receiver. Nominal capacitance is
0.1
µF.
The 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
placed physically close to the
appropriate pins on the HDMP-
1636/46. Keeping the lines short
will prevent them from picking
up stray noise from surrounding
lines or components.
GND_TXHS
V
CC
_TXHS
V
CC
_TXECL
V
CC
_TX
GND
V
CC
_RX
GND_RXHS
V
CC
_RXHS
V
CC
*
* SUPPLY VOLTAGE INTO V
CC
_RXA AND V
CC
_TXA SHOULD
BE FROM A LOW NOISE SOURCE. ALL BYPASS CAPACITORS
AND PLL FILTER CAPACITORS ARE 0.1 µF.
GND
V
CC
_RXHS
GND_RXA
V
CC
_RXA
RXCAP1
Figure 12. Power Supply Bypass.
Start-up Procedure:
The transceiver start-up
procedure(s) use the following
conditions: V
CC
= +3.3 V
±
5%
and REFCLK = 125 MHz
±
100
ppm.
After the above conditions have
been met, apply valid data using a
balanced code such as 8B/10B.
Frequency lock occurs within
500
µs.
After frequency lock,
phase lock occurs within 2500 bit
times.
Transceiver Power
Supply Bypass and Loop
Filter Capacitors
Bypass capacitors should be
liberally used and placed as close
as possible to the appropriate
PRE-RELEASE PRODUCT
DISCLAIMER:
This product is in development at
the Hewlett-Packard CSSD in San
Jose, California. Until Hewlett-
Packard releases this product for
general sales, HP reserves the right to
alter specifications, features,
capabilities, functions, manufacturing
release dates, and even general
availability of the product at any time.
724
AGILENT [ AGILENT TECHNOLOGIES, LTD. ]
