Evaluation Board User Guide
UG-559
Rev. B | Page 3 of 8
EVALUATION BOARD QUICK START PROCEDURES
INITIAL SETUP
The
AD8338
evaluation board needs only a few external
connections. Setting up this board for the first time requires
the following:
•
A dc supply to power the evaluation board from 6 V to
20 V (6 V is preferred)
•
Cables to connect the board to the signal source
•
Cables to connect the board to the oscilloscope
INITIAL CONNECTIONS
First, connect two SMA to BNC cables from the output SMA
connectors (OUTP, OUTM) to the oscilloscope. Set the
oscilloscope to 1 MΩ input impedance. The
AD8338
is not
specified to drive 50 Ω impedances; therefore, it must drive a
high impedance load.
When using the
AD8338
in standalone mode, which is fully
differential in and out, set up the signal source as a differential
output using two channels. Set the phase of the first channel to
be in phase and set the second channel to be out of phase (180°).
-
Figure 2. Basic Connections for the
AD8338
Evaluation Module,
Differential Mode
POWERING UP THE
AD8338
Take the following steps to power up the
AD8338
evaluation
board:
1. Before applying any signals or supplies, set the jumpers to
their default settings, as indicated on the printed circuit
board (PCB).
2. Set the power supply to 6 V.
3. Enable the output.
4. Set the output amplitude on the signal generator to 0.1 V
on each channel (200 mV difference amplitude). Note
that
the
AD8338-EVALZ
board includes on-board 50 Ω
terminators.
5. Adjust the potentiometer (labeled GAIN ADJ) counter-
clockwise until stopped.
6. Enable the outputs.
Upon correct configuration, the output signal appears on the
oscilloscope. Manually adjust gain by adjusting the GAIN ADJ
potentiometer. If these work, then basic operation of the
AD8338-EVALZ
is verified.
CONFIGURING FOR SINGLE-ENDED INPUT,
DIFFERENTIAL OUTPUT
The
AD8338-EVALZ
is equipped with the
ADA4940-1
differential driver amplifier. Bring this amplifier into the signal
chain through the setting of the J5, J6, J7, and J8 jumpers as
highlighted in Figure 3.
When these jumpers (J5 to J7 and J8) are set, the input
connectors (J3 and J4) are disconnected from the
AD8338
, and
fed into the
ADA4940-1
. Input Connector J4 becomes inert and
is no longer necessary and Input Connector J3 becomes the
single-ended input source. The
ADA4940-1
operates in unity-
gain difference.
Figure 3.
AD8338-EVALZ
Board with Jumpers Set for
Single-Ended Input Mode
OSCILLOSCOPE
AD8338
EVALUATION BOARD
DIFFERENTIAL
OUTPUT
SIGNAL
SOURCE
1
1510-
002
1
1510-
003
Downloaded from
Downloaded from
Downloaded from
