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ADF4351+ADL5801

Question asked by xubing on Nov 22, 2013
Latest reply on Dec 7, 2013 by xubing

Hi,

 

I'm working with the ADF4351+ADL5801 project, in which the ADF4351 provides a 1.7 GHz LO for the mixer ADL5801. I referred to the Circuit Note CN-0239 which is attached with the message. In this circuit note, the two bias inductors L2 and L3 on the evaluation board are replaced with two-50 Ohm pull-up resistors. So, it presents a nominal differential impedance of 100 Ohm, but the differential input impedance of the LO port  of the ADL5801 is 50 Ohm. Why not use two-25 Ohm resistors to replace L2 and L3 to get a 50 Ohm differential impedance?

 

Besides, in Table. 2 of this circute note, T2/T4/T7 on the ADL5801-EVALZ is repalced with two-0 Ohm resistors, so what's the impedance of the LO port of ADL5801?

 

Regards!

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