Hello
I have a question about the AD9375 when operating the RX near full scale.
Our configuration is as follows:
ZCU102 carrier board running the ADI 2022.2 HDL reference project.
ZCU102 is running Petalinux with the 2022.2 meta ADI layer.
ADRV9374 evaluation board on ZCU102.
AD9375 LO set to 4800MHz. Providing an input signal to RX1 from a signal generator at 4801MHz. The level of the signal generator is increased slowly to approach full scale input on the AD9375.
We used the AD9371 Filter Wizard to generate the profile information and this was loaded into the Petalinux device tree.
We are seeing the following:
As the input signal approaches full scale, we start to see high frequency oscillations in the RX output sample data. The oscillations reduce and then the original signal returns. Below a certain level, no oscillations occur.
This is a screen capture of IIO Oscilloscope showing the oscillations.
If you zoom in, you can see the oscillation that starts to occur:
You can also see that the oscillation starts to happen at around 26000 with still some headroom to the 32767 limit.
I have tried disabling the QEC tracking correction and it made no difference.
Is it possible that a FIR filter inside the digital processing chain of the AD9375 is becoming unstable or is receiving an impulse response from the ADC stage that is making it unstable?
Is this expected behaviour for this type of ADC? Or is there something I need to do to change the behaviour?
Thank you
Gavin
