high noise when using DCDC in TX mode

[victor passe]

Hi, This is what constant carrier looks like at 2450MHz on my custom board using DCDC disabled

This is with DCDC enabled:

It can also look much worse with no real peak and just a wide band of energy,

I have followed the reference schematic in the product spedification. What could be the problem?

[Andreas]

Hi,

 

Your span is a little narrow, what's inside will drown in the carrier. How does what's outside compare, and how does the spectrum look when the carrier is modulated?

Your C6 is larger than we recomend (1nF), though I do not expect any large effects from changing this you might want to try it.

 

Best regards,

Andreas