Datasheet

REV. B
AD9764
–17–
of the DAC can be evaluated. Nonlinearities associated with the
DAC will create spurious tones of which some may fall back into
the “empty” channel thus limiting a channel’s carrier-to-noise
ratio. Other spurious components falling outside the band of
interest may also be important, depending on the system’s spectral
mask and filtering requirements.
This particular test vector was centered around one-half the
Nyquist bandwidth (i.e., f
CLOCK
/4) with a passband of f
CLOCK
/16.
Centering the tones at a much lower region (i.e., f
CLOCK
/10)
would lead to an improvement in performance while centering
the tones at a higher region (i.e., f
CLOCK
/2.5) would result in a
degradation in performance. Figure 40a shows the SFDR vs.
amplitude at different sample rates up to the Nyquist frequency
while Figure 40b shows the SFDR vs. amplitude within the
passband of the test vector. In assessing a DAC’s multitone
performance, it is also recommended that several units be tested
under exactly the same conditions to determine any performance
variability.
A
OUT
– dBFS
SFDR – dBc
80
50
–20 –15 0
–10 –5
70
60
10 MSPS
100 MSPS
20 MSPS
50 MSPS
40
30
75
65
55
45
35
Figure 40a. Multitone SFDR vs. A
OUT
(Up to Nyquist)
SFDR – dBc
50
70
60
40
75
65
55
45
80
10 MSPS
20 MSPS
50 MSPS
100 MSPS
A
OUT
– dBFS
–20 –15 0–10 –5
Figure 40b. Multitone SFDR vs. A
OUT
(Within Multitone
Passband)
AD9764 EVALUATION BOARD
General Description
The AD9764-EB is an evaluation board for the AD9764 14-bit
DAC converter. Careful attention to layout and circuit design,
combined with a prototyping area, allows the user to easily and
effectively evaluate the AD9764 in any application where high
resolution, high speed conversion is required.
This board allows the user the flexibility to operate the AD9764
in various configurations. Possible output configurations include
transformer coupled, resistor terminated, inverting/noninverting
and differential amplifier outputs. The digital inputs are designed
to be driven directly from various word generators with the
onboard option to add a resistor network for proper load termi-
nation. Provisions are also made to operate the AD9764 with
either the internal or external reference or to exercise the power-
down feature.
Refer to the application note AN-420, Using the AD9760/AD9764/
AD9764-EB Evaluation Board for a thorough description and
operating instructions for the AD9764 evaluation board.