1
Rev. 0
DESCRIPTION
LTC6955/LTC6955-1
Ultralow Jitter 11 Output
Fanout Buffer
Demonstration Circuit 2611A features the
, Ultralow Jitter 11 Output Fanout Buffers.
By default, the DC2611A is powered from a single 3.3V
supply. An option is provided to power to the DC2611A
from dual supplies, allowing for the LTC6955’s output
supply pins to connect to an LTC Silent Switcher
®
and the
LTC6955 input supply pin to connect to a low noise LDO.
The differential inputs and six of the differential outputs
are populated with 0.5" spaced SMA connectors. These
outputs are AC-coupled with 50Ω transmission lines
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making them suitable to drive 50Ω impedance instru-
ments. The remaining four differential outputs are termi-
nated with 100Ω.
A calibration path is provided to aid in accurate LTC6955
propagation delay measurements. The calibration path
can be also reconfigured as a DC path, which allows for
a convenient method of locking the LTC6955 outputs to
an external PLL/VCO, as shown in Figure 2.
Design files for this circuit board are available
Figure 1. DC2611A Connections
CAL_IN,
SMA
Single Supply 3.3V Input,
banana jacks J27 & J28
OUT1, CML
AC-coupled
Outputs, SMA
OUT0, CML
AC-coupled
Outputs, SMA
CAL_OUT,
SMA
OUT8, CML
AC-coupled
Outputs, SMA
OUT10, CML
AC-coupled
Outputs, SMA
IN Input, SMA
VIN33 Option,
Refer to
DC2611 Reconfiguration
OUT6, CML
AC-coupled
Outputs, SMA
OUT4, CML
AC-coupled
Outputs, SMA
TEMP, turret
OUTPUT SEL,
Switches
FILT, Header
