The output impedance of AD8347

Document created by analog-archivist Employee on Feb 23, 2016
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I want to know the baseband output impedance of AD8347 which can help design
the filter considering the impedance matching. And is it necessary to add an
amplifier driver between the AD8347 and the AD9216? Could you please help us
and give some comments on it?


The output impedance of AD8347 will depend on the application. If you use the
output of mixer( without IF amplifier), the output impedance is only 3 Ohm, it
is current output.
If you use the output from the IF amplifier, the output impedance is 1M//3pF.
I don’t know if you have blocking requirement in their system, if yes, please
consider ADL5387 or ADL5382 for much better performance for receiver. The IIP3
of AD8347 is a bit poor. And the output capability is also small. The big
advantage is high gain, but it really depends on the input signal, if the input
signal is big, then the gain is useless, the chip will get saturated. If they
choose ADL5387 or ADL5382, the baseband DGA can be AD8366. This part was
designed just for zero IF application.