Analog Discovery 2 - Noise & Voltage regulation

[DroneGuru]

Hello,

I'm trying to measure the internal noise of the AD2, to get an idea of the "real" effective number of bits.
When I put the CH1 to ground, I got something like this :

I have 2 questions :

- What is the light orange shape around the signal, and how can I delete it ?

- When powering the AD2 with External Power Supply, when dropping the voltage, the current consumption increase. That's typically a DC/DC switching power supply behavior. So is there by any chance a DC/DC switching power supply inside the AD2 to regulate the External power source ?

 

Thanks by advance for your support.

Best regards,

Hugo

[attila]

Hi @DroneGuru

That is the noise band, see the following post:

You may want to set the sampling rate to maximum or to the frequency you want to use it.
At lower rates by default the samples are averaged. It can be changed under channels gear-dropdown.
To see internal noise short the scope P/N inputs.

 

Yes, there are various internal rails and buck-boost for user supplies, see:
https://digilent.com/reference/test-and-measurement/analog-discovery-2/hardware-design-guide

[DroneGuru]

On 5/13/2022 at 4:41 PM, attila said:

Hi @DroneGuru

That is the noise band, see the following post:

You may want to set the sampling rate to maximum or to the frequency you want to use it.
At lower rates by default the samples are averaged. It can be changed under channels gear-dropdown.
To see internal noise short the scope P/N inputs.

 

Yes, there are various internal rails and buck-boost for user supplies, see:
https://digilent.com/reference/test-and-measurement/analog-discovery-2/hardware-design-guide

 

Hello,

Thanks a lot for your reply !

The noise you have is pretty much what we measured, but we need to have a 20 Mhz sampling rate for our project.

Concerning the internal Buck-boost converter etc, is it possible to have a global Schematic of the AD2 & the AD Pro ? We purchased both of them and we're trying to know where the noise come from and having multiple parts of an unknown schematic isn't quite practical.

This will help us a lot for our university project !

Thanks by advance,

Hugo

[attila]

Hi @DroneGuru

The schematics are not public but here you can find a detailed description of AD2:
https://digilent.com/reference/test-and-measurement/analog-discovery-2/hardware-design-guide