I am trying to test a masked design on CW305 (NAE-CW305-04-7A100-0.10-X) with Picoscope 5000 series. The design is relatively big and consumes 50% of the LUTs in CW305. I basically run some experiments, collect the measurements and then plot the t-test figure for the implementation.
I was observing wave-like structures in my t-test, which I could not explain and I decided to plot the raw measurement data. Then I observed that the wave-like pattern also appears in the measurement data after an operation causing high vol/power consumption.
In the attached plot, you will see the output of +20dB amplified SMA connector for a series of operations involving polynomial arithmetic.
In the beginning, the measured data seems ok for a short time. Then, I start an operation showing high vol/power consumption and creating a lot of spikes. After that operation, this wave-like pattern appears and it resides during the whole measurement. If I keep the circuit in idle long enough after that operation, the wave gradually diminishes.
Did anyone face this behavior before? Do you have any suggestions to remove this wave-like pattern immediately after the operation?