Secondary Panel Description
IMPORTANT: Since the ADC signal and clock inputs are not provided with additional protection
circuitry on this board, the burden is on the user to not overdrive the inputs to the extent of
damaging them. An "Over-range" LED is provided for each channel to indicate that the signal
amplitude is beyond the ADC full-scale range. Keep the signal amplitude within the operating
ratings as specified in the datasheet. Thus, the safe method of setting the signal amplitude to full-
scale level is to utilize the LED as described in the previous paragraph to roughly obtain the full-
scale amplitude and then inspect the captured data in the software's time-domain plot to fine tune
the amplitude to the desired level.
2.6.3
Acquire and Display Data
Perform a data acquisition by clicking the Acquire Data button (Item #5 in
). The acquired data will
now appear in the (default) time domain plot window. Switch to the frequency-domain window (FFT) using
the WaveVision 5 controls. Type Ctrl-r to obtain the summary of the acquisition. Place the software in
continuous mode (Item #6 of
) and then acquire again. This is to confirm that the Over-range LED
method used earlier indeed gave a signal to the ADC that is within –0.5 to –1.0 dB of the full-scale range.
If not, adjust the input signal generator's signal power to approximately –0.5dB of full scale.
At this point, dynamic performance metrics similar to those shown on the reference data shipped with the
board may be obtained. One of the basic variables that you may experiment with at this point is to change
the input signal strength and frequency. Please note that to achieve the reference performance, band-
pass filters similar to the items referenced in Section 2.2 should be used. The absence of these filters on
the input signal or external clock will usually result in sub-standard performance.
The displayed units should be in dBFS as selected earlier. You may switch the units to dBc and back to
dBFS as desired.
2.6.4
It is also possible to apply a high-quality external signal source to the clock input rather than using the
on-board LMX2541 clock synthesizer. This will help quantify the LMX2541's performance in an ultra-
high-speed signal-path such as this one. When connecting an external clock source, the generator
amplitude should be set to 0dBm. Experiment with the clock signal strength to determine what effect
this has on the channel performance. Care should be taken to not 4 dBm at the clock input, to
avoid damage to the ADC.
The external clock source is enabled through the register control panel in the software after applying the
signal generator to the Clock input SMA.
The external clock source should be disconnected or turned off when the on-board clock source is
selected. Failure to do so will result in poor performance due to the mixing of the on-board clock
and the small amount of external clock signal leaking through the clock selection relay.
It is important to keep in mind that if the ADC's operating conditions are changed in any significant way,
especially temperature, the ADC should be calibrated again before proceeding.
Please refer to the WaveVision 5 Users' Guide and integral Help feature for more information concerning
the software.
3
Secondary Panel Description
Please refer to the WaveVision 5 Users Guide for detailed descriptions of the remaining Left and Right
panels, and additional Main Panel features.
24
ADC1xDxxxx(RF)RB Reference Board
SNAU146 – September 2013
Copyright © 2013, Texas Instruments Incorporated