Datasheet

Evaluation Board User Guide UG-294
Rev. B | Page 5 of 48
DEFAULT OPERATION AND JUMPER SELECTION
SETTINGS
This section explains the default and optional settings and modes
available on the AD9644 and AD9641 Rev. A evaluation boards.
Power Circuitry
Connect the switching power supply that is included in the
evaluation kit between an ac wall outlet of 100 V to 240 V at
47 Hz to 63 Hz and the P201 jack.
Analog Input
The Channel A and Channel B inputs on the evaluation board
are set up for a double balun-coupled analog input with a 50 Ω
impedance. This input network is optimized to support a wide
frequency band. See the AD9644 data sheet for additional infor-
mation about the recommended networks for various input
frequency ranges. The nominal input drive level is 10 dBm to
achieve 2 V p-p full scale into 50 Ω. At higher input frequencies,
slightly higher input drive levels are required due to losses in
the front-end network.
Optionally, on the AD9644 evaluation board, Channel A and
Channel B inputs on the board can be configured to use the
AD8376 digitally controlled variable gain amplifier (VGA). The
AD8376 is included on the AD9644 evaluation board at U401.
However, the path into and out of the AD8376 can be configured
in many different ways depending on the application; therefore,
the parts in the input and output paths are left unpopulated. Users
should see the AD8376 data sheet for additional information
about this part and for configuring the inputs and outputs. The
AD8376 by default is held in power-down mode but can be enabled
by adding a jumper on P401 (Channel A) or P402 (Channel B).
Optionally, on the AD9641 evaluation board, the Channel A input
on the board can be configured to use the ADL5562 ultralow
distortion RF/IF differential amplifier. The ADL5562 is included
on the AD9641 evaluation board at U401. However, the path
into and out of the ADL5562 can be configured in many ways
depending on the application; therefore, the parts in the input and
output paths are left unpopulated. Users should see the ADL5562
data sheet for additional information on this part and for config-
uring the inputs and outputs. The ADL5562 by default is held in
power-down mode but can be enabled by adding a jumper on
P401. The ADL5562 can also be substituted with the ADA4937-1
or the ADA4938-1 to allow evaluation of these parts with the
analog-to-digital converter (ADC).
AD9644/AD9641
33Ω
0.1µF
2
V p-
p
VIN+
VIN–
VCM
8.2pF
8.2pF
33Ω
0.1µF
S
0.1µF
8.2pF
36Ω
36Ω
SP
A
P
49.9Ω
49.9Ω
09941-003
Figure 3. Default Analog Input Configuration of the AD9644/AD9641