Rev 13 Nov 2013 00:23 | Page 4
The evaluation board provides the support circuitry required to operate the
in
their various modes and configurations. Figure 1 shows the typical bench characterization setup used
to evaluate AC performance. It is critical that the signal sources used for the analog input and clock
have very low phase noise (ideally ~100 fs rms jitter) to realize the optimum performance of the
signal chain. Proper filtering of the analog input signal to remove harmonics and lower the integrated
or broadband noise at the input is necessary to achieve the specified noise performance.
AD9257/9637 Design Support <Coming Soon>
for the complete schematics and layout diagrams.
These diagrams demonstrate the routing and grounding techniques that should be applied at the
system level when designing application boards using these converters.
Power Supplies
This evaluation board comes with a wall-mountable switching power supply that provides a 6V, 2A
maximum output. Connect the supply to a 100V ac to 240V ac, 47Hz to 63Hz wall outlet. The output
from the supply is provided through a 2.1mm inner diameter jack that connects to the printed circuit
board (PCB) at P101. The 6V supply is fused and conditioned on the PCB before connecting to the low
dropout linear regulators that supply the proper bias to each of the various sections on the board.
The evaluation board can be powered in a nondefault condition using external bench power supplies.
To do this, remove the E101, E102, E104, E105, E111, E112, E113, E114, E115 and E116 ferrite beads
to disconnect the bench supply traces from the on-board LDOs. Note that in some board
configurations some of these might already be uninstalled. P102 and P103 need to be installed to
connect external bench supplies to the board. E106, E107, E108 and E109 need to be populated to
connect P102 and P103 to the board power domains. A 1.8V , 0.5A supply is needed for
1.8V_DUT_AVDD and 1.8V_DRVDD. Although the voltage requirements are the same for
1.8V_DUT_AVDD and 1.8V_DRVDD, it is recommended that separate supplies be used for each of
these.
Two additional supplies, 5.0V_AVDD and 3.3V_AVDD, are used to bias the optional input path
amplifiers and optional
clock chip. If used, these supplies should each have at least 0.5A
current capability.
Input Signals
When connecting the ADC clock and analog source, use clean signal generators with low phase noise,
such as the Rohde & Schwarz SMA, or an equivalent. Use a shielded, RG-58, 50Ω coaxial cable
(optimally 1 m or shorter) for connecting to the evaluation board. Enter the desired frequency and
amplitude (see the Specifications section in the data sheet of the respective part). When connecting
the analog input source, use of a multipole, narrow-band band-pass filter with 50Ω terminations is
recommended. Analog Devices uses band-pass filters from TTE and K&L Microwave, Inc. Connect the
filters directly to the evaluation board.
If an external clock source is used, it should also be supplied with a clean signal generator as
previously specified for the analog input signals. Analog Devices evaluation boards typically can
