we are currently using the ADL5565 as a balun alternative from DC to 3GHz and would like to exand it to 6GHz or higher. Unfortunately, the provided S-Parameters file ends at 3GHz and looks somehow weird:
Thus, either the stated input resistance of 100 Ohm and 0.5 pF capacitance from the datasheet is completely wrong, or the S-Parameters are wrong. If you look at the datasheet of the ADL5569, the input should look more like what you expect of R || C:
Is there any chance to get S-Parameters of the ADL5565 higher than 3GHz?
The S-parameters are limited to 3 Ghz, and are taken with 50 ohm loading by definition. As you see in our datasheet, the spec is written with a 200 ohm differential load on the output port. This output loading will effect the input impedance, as shown in the attachment. Let me know if you have further questions.
thanks for the explanation. The output impedance is clear to me, but not the stated 100 Ohm input (3.3V, 12dB). This seems to be only valid for f < 1GHz. However, I am interested in the input impedance up to 10 GHz for matching our active balun. So it seems that Analog has never characterized the ADL5565 higher than 3 GHz. Bad luck for me - measuring and deembedding always introduces the risk of uncertainty if not done properly...
Moved to its proper community RF and Microwave.