I'm using the ADF4351 configured to generate two fixed frequencies simultaneously, 3000 MHz on the Aux output and 375 MHz (divided by 8) on the Main output.
When the divide-by-8 is enabled, the 3000 MHz signal has 375 MHz sidebands present. Their amplitude is around -40 dBc. Their relative amplitude will often jump, sometimes as much as 10 dB, when subsequent writes are made to R0. Changing the output power settings in R4 does not affect their relative amplitude.
My register settings are:
This design uses a 10 MHz reference.
Any suggestions for reducing the level of these sidebands?