Use ADF4158 with frequency below 0.5 GHz

Question

I want to use the ADF4158 with a 100 MHz to 500 MHz RF input frequency (RFin). 
 In accordance with the ADF4158 specification (please see page 3 of data sheet) a condition of the PLL at frequencies below 500 MHz is 
 RFin slew rate > 400V/us. 
 Is there an example of a simple solution to this problem - Such as the comparator or LVPECL driver ? 
 Vlad

ADIApproved · Answer

Hi Vlad, 
 RFin is slew rate limited. For frequencies below 500MHz slew rate > 400V/us. High speed comparator is a solution in here. ADCMP553 should work. The output is PECL or LVPECL. It has to be slightly attenuated (to 600mV differential), since there are protecting diodes on RFin. There should be a CFTL on that available soon. 
 Regards, 
 Dawid