ADS42JB46: Dither Disable

Hi RJH,

Thank you for the quick response on this. The customer is asking because they are seeing non-monotonic behavior on IMD3 data as shown in the figure below. With dither, it should be better than this, more linearity.

Can you provide some feedback on the data they are getting below from the ADS42JB46 EVM (Using the J56 JESD capture card)?

Regards,

~John

The customer has also provided this more granular graph:

Regards,

~John

Hi John,

How does the ADC input drive circuit compare with that used on the ADS42JB46 EVM which is shown in Figure 79 of datasheet? I want to be sure the degradation in IM performance does not occur before the ADC.

Thanks,

Eben

Hi Eben,

This data is taken on the EVM, with a direct input from a R&S SMW200A.

Regards,

~John

John,

Let me investigate more and get back to you on this next week.

Thanks,
Eben.

Hi John,

I assume they are using a power combiner to combine the outputs of the two RF sources from the SMW200A? Can you have them double check that the IMD is not limited by the RF source or the power combiner?

Thanks,
Eben.

Hi Eben,

The customer has tested out the combiner and it isn't affecting the performance:

 I put filters after the combiner and used spectrum analyzer to measure the IMD products of the two-tone to make sure it’s decent as shown in the figure below.

 

 

Regards,

~John