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dc1884af
DEMO MANUAL DC1884A
QUICK START PROCEDURE
Setup
If a DC1371 data acquisition and collection system was
supplied with the DC1884, follow the DC1371 Quick Start
Guide to install the required software and to connect the
DC1371 to the DC1884 and to a PC.
DC1884 Board Jumpers
The DC1884 board should have the following jumper set-
tings as default positions (as per Figure 1):
JP14: PAR/SER:
Selects Parallel or Serial Programming
Mode. (Default: Serial)
Optional Jumpers AJ3 and J6: Term:
Enables/Disable
Optional Output Termination. (Default: Removed)
JP5: I
LVDS
:
Selects Either 1.75mA or 3.5mA of Output
Current for the LVDS Drivers. (Default: Removed)
JP1 and JP2: Lane:
Selects Either 1-Lane or 2-Lane Output
Modes (Default: Removed)
Note: The DC1371 does not support 1-Lane operation.
JP9: SHDN:
Enables and Disables the LTM9011.
(Default: Removed)
JP8: WP:
Enable/Disables Write Protect for the EEPROM.
(Default: Removed)
Note: Optional jumper should be left open to ensure proper
serial confi guration.
Applying Power and Signals to the DC1884
The DC1371 is used to acquire data from the DC1884. The
DC1371 must fi rst be connected to a powered USB port
and have 5V applied power before applying 3.5V across
the pins marked V
+
and “GND” on the DC1884. DC1884
requires 3.5V for proper operation.
The DC1884 demonstration circuit requires up to 700mA
depending on the sampling rate and the A/D converter
supplied.
The DC1884 should not be removed or connected to the
DC1371 while power is applied.
Analog Input Network
For optimal distortion and noise performance, the RC
network on the analog inputs may need to be optimized
for different analog input frequencies. For input frequen-
cies above 70MHz, refer to the LTM9011 data sheet for a
proper input network.
In almost all cases, fi lters will be required on both analog
input and encode clock to provide data sheet SNR.
The fi lters should be located close to the inputs to avoid
refl ections from impedance discontinuities at the driven
end of a long transmission line. Most fi lters do not present
50Ω outside the passband. In some cases, 3dB to 10dB
pads may be required to obtain low distortion.
If your generator cannot deliver full-scale signals without
distortion, you may benefi t from a medium power amplifi er
based on a gallium arsenide gain block prior to the fi nal
fi lter. This is particularly true at higher frequencies where
IC based operational amplifi ers may be unable to deliver
the combination of low noise fi gure and high IP3 point
required. A high order fi lter can be used prior to this fi nal
amplifi er, and a relatively lower Q fi lter used between the
amplifi er and the demonstration circuit.