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ADF4351: output matching for 800 and 2100MHz output

Question asked by luca.banchi on Oct 26, 2016
Latest reply on Jan 9, 2017 by icollins

Dear support,


in my deign I involve couple of ADF4351 Synth working on different frequency ranges: 800MHz and 2100MHz.

The point is how to exactly match the output.

1) Pag. 27 of the ADF4351 datasheet shows two output stage option (fig. 38 and fig. 39) and the relative values for components for different frequency ranges.

Focusing on the single-ended solution reported in fig. 38 on pag. 27: on the ADF4351 eval-board pag.12 I found a different choice of component for a configuration similar on that reported in figure 38 of the ADF4351 datasheet: the value of the RF choke is 7.5nH on the eval-board and 3.9nH on the datasheet.

Could you please clarify what are the best values for matching components on the two different frequencies (800MHz and 2100MHz)?


2) In case of single ended operation, which is correct scheme to terminate the unused output?


3) Moreover, regarding the LC Balun matching option reported in fig. 39 on pag. 27: on Table 8 the values for the LC components are reported, but the model and the manufacturer for those LC components are not specified . Does the matching require a particular choice of those components, or generic L and C with the specified values are ok for the design on both frequency (800MHz and 2100MHz)?

I attached a sketch of my LC Balun matching network, is it correct for the 800MHz application?


4) Finally, what is the difference in term of output power for the two output matching configuration on both frequency?


Thank you for your help