Hi all,
we are using the ADC12J4000 on one of our board (4 ADCs). It behaves globally as expected, except in a small part of the spectrum where the SFDR loose about 10dB.
Did anybody see such behaviours?
I did test with the following sampling frequencies : 3.0, 3.2, 3.4, 3.6, 3.8 and 4.0GHz.
Depending on the sampling frequency, SFDR degradations happens when the carrier is between 80MHZ an 100MHz from Fsampling/2. There are 2 spurious on each side of the carrier which appear when the carrier is in this part of the spectrum.
If I lower the carrier power, then these spurious disappear suddenly when the level goes below between -3.5dBFs and -4dBFs (depending on the ADC).
Moreover, the zone location seems to be proportional to the sampling frequency.
To do the SFDR measurements I removed from the spectrum the signal's harmonics and the interleaving offset spur at Fs/4.
The ADC configuration is as follow:
- enable large signal
- foreground calibration
- disabled background calibration
- enable timing calibration
- carrier level about -1dBFs
regards,
Manuel