LMX2820: VCO doubler enabled attenuates power output

Oliver McConnell

Part Number: LMX2820

Tool/software:

I have been working with the LMX2820 on custom hardware and found that I can program the device successfully at all frequencies at or below 11.2GHz, but anything above that which requires the VCO doubler shows an attenuated output around -70dBm. The device reports that it is locked and my spectrum analyzer shows that the attenuated signal looks to be at the correct frequency, but the output power is much too low to do anything with. Is there a different sequence or some requirements when using the VCO doubler that I may be missing?

11 months ago

0 Noel Fung 11 months ago

TI__Guru** 108130 points

Hi Oliver,

Whenever the VCO doubler is engaged, DBLR_CAL_EN should be set to =1 so that when a VCO calibration is triggered, both VCO and the doubler will be calibrated.

0 Oliver McConnell 11 months ago in reply to Noel Fung

Prodigy 80 points

I tried that and it increased the amplitude only slightly. I now see the signal around -43dBm so there must still be something else that is keeping the signal in an attenuated state.