Analog Devices AD604 - Manual (Page 24)

AD604
EVALUATION BOARD
Figure 55 is a photograph of the AD604 evaluation board assembly.
Multiple input connections, test points, jumper selectable options,
and on-board trims offer convenience when configuring the
AD604 in various operating modes.
The evaluation board requires only a dual 5 V supply capable of
200 mA or higher to operate both channels. Prior to shipment,
the evaluation board is fully tested. Users need only attach
power supply leads and the appropriate test equipment to
the board.
Because of this flexibility, not all component positions on the
board are populated when the board is shipped. Installing or
changing additional parts is optional.
The AD604-EVALZ is fabricated on a 4-layer board with inner
power and ground layers. The AD604 is a stable, trouble-free
device; however, as with all high-frequency integrated circuits,
power and ground planes help to ensure consistency in
performance.
Figure 55. AD604 Evaluation Board Assembly
USING THE PREAMPLIFIER
To use the preamplifiers, simply connect a signal source to CH1
PREAMP IN and/or CH2 PREAMP IN via the SMA connectors.
Referring to the schematic in Figure 61, the input lines are
terminated with 50 U resistors at locations R7 and R8.
To enable the preamplifiers, insert jumpers in the JP8 and JP9
rightmost positions; this connects COM1 and COM2 to ground.
Power down the preamplifiers by inserting jumpers in the JP8
and JP9 leftmost positions.
Figure 56. AD604 Evaluation Board—Component Side Silk Screen
SX INPUT CONNECTIOr
The DS^inputf can be lonnected iA^slngle-ended|3r differential
coRfigurations. sM^-lonnfejtors are provided for-lach of the
inputs and are labeled CHx VGA IN (+) and CHx VGA IN (-).
JP6 and JP15 select between the preamplifier outputs and the
DSX inputs.
For direct drive of the Channel 1 VGA, insert a jumper in the
top position of JP6. For direct drive of the Channel 2 VGA,
insert a jumper in JP14 and verify that there are no jumpers in
JP12 and JP13. Refer to the schematic shown in Figure 61 for
circuit details.
Differential DSX Inputs
Differential inputs are possible using both polarities of the
VGA SMA connectors and appropriate jumpers. Inserting a
jumper in the lower position of JP5 selects the negative input
of Channel 1. A jumper in the top position of JP6 selects the
positive input of Channel 1. A jumper in the JP16 rightmost
position selects the negative input of Channel 2, and a jumper
in JP14 selects the positive input. Verify that there are no jumpers
in JP15 or JP13.
Because the VGA section of the AD604 uses a single 5 V supply,
the DSX inputs are ac-coupled. Decoupling capacitors are provided
on the evaluation board.
The DSX input impedance is approximately 200 U. Optional
66.5 U resistors can be installed across the inputs at positions
R5, R6, R9, and R10 to establish a 50 U terminating load.
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