Hi everyone
I would need to get the ENOB for an ADC I am testing.
I know I would need to measure a constant voltage many times to get an histogram for ADC output and get ENOB with the following expression:



The ADC is a Delta Sigma and I need to use the input range Vref/2= 512 mv. The Verf is internal to the ADC = 1.024 mv
The ADC have other Input ranges and they goes from +/- 2.048 mv, +/- 1.024 mv, .........up to Vref/16.
The point of my question is about what how can I get a stable level of voltage to get that Histogram keeping in mind that the noise level of that voltage which drive the ADC should be low enough.
Sorry if it is a silly question, I am learning about mixed signals.
Thank you very much for your time.

 

Help us to help you: what is the part number of the ADC you are using?

 

I would assume this is for a Delta-Sigma ADC

https://www.maximintegrated.com/en/app-notes/index.mvp/id/5384

ENOB measurement setup:
https://cdn.rohde-schwarz.com/pws/d...notes/1er03/ENOB_Technical_Paper_1ER03_1e.pdf

 

Help us to help you: what is the part number of the ADC you are using?[/QUOTE


Hi OBW0549

I'm currently using the Cypress PSoC 5LP which is a Cortex M. It is system on chip with many analog and digital resources that you can enable according to the necessity.

I have attached for you guys the component 20 bits ADC Delta Sigma data sheet.

 

The point of my question is about what how can I get a stable level of voltage to get that Histogram keeping in mind that the noise level of that voltage which drive the ADC should be low enough.

I think if you're trying to measure the ADC code distribution to get the RMS noise, you don't need an external stable, low-noise voltage source; you can do that with zero volts differential input. Just connect the +Input and -Input pins together and connect them to the nVref pin, bypassed with a 10μF or larger capacitor as described on page 14 of the datasheet document you posted. I don't see any need to test with a non-zero differential voltage input.

 

Hi OBW0549

Thank you very much, I'm working on that.
Regards,