LMX2595: Spur issue at the frequency ramp output

Sudheer Kumar K

Part Number: LMX2595

We are using LMX2595 PLL in one of our design. We want use Ramp function in that with frequency ranging from 5.71 GHz to 5.9 GHz. we are observing more spurs in 1GHz span. Attached is the settings we followed, loop filter value used and Spectrum we are getting.

Kindly suggest me how can I reduce the spurs in the band?

over 1 year ago

0 Noel Fung over 1 year ago

TI__Guru* 81550 points

Hi Sudheer,

Basically spurs are expected during ramping as the PLL will be running into fractional channels. Secondly, multiple VCO calibrations are performed during ramping, so the VCO frequency may swing way beyond your ramping frequency range. I can run a test to see how we can improve spurs with the configuration, stay tuned.