The MAX2659 requires an off-chip input matching. Only a 6.8nH inductor in series with a DC-blocking capacitor(470pF) is needed to form the input matching circuit.
Why recommend 470pF + 6.8nH??
this LC resonant frequency is 0.09GHz, not 1.5742GHz.
is it to block all bands and then amplify only the corresponding frequency range?
Hi latte,
The recommendation according to this FAQ is for the DC blocking due to the DC bias inside the RF IN of MAX2659, and provide/form an input matching circuit.
Use this table from the datasheet to know the LC combination for the desired Band/frequency of operation.
The frequency computation might be a combination of the external LC + what's inside the RFN and looking at some of the TPCs in the datasheet, the configuration definitely shows 1.575Ghz frequency of operation. Like the return loss graph:
And you're right it's used to amplify specific frequency range.
-Dann
