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bias tee advice for GPS LNA

bias tee advice for GPS LNA

bias tee advice for GPS LNA

I'm prototyping a GPS LNA circuit and am trying to figure out a good design (that wont cause a great mismatch) that will allow me to strip off the DC and couple the RF to the LNA circuit. The RF and DC come from to coax to the antenna puck (with LNA underneath).

 I know a bias tee configuration should do the trick, but any suggestions on values cap and inductor to use at the point where the center conductor (carrying both) hits the PCB? Is there a general design rule in the L-band?

Looking ideally at chip stuff (0402) package?

RE: bias tee advice for GPS LNA

Shoot for an inductor impedance that is at least 10x the circuit impedance at the frequency of interest.  Your circuit is 50 ohms, so inductor impedance should be >500 ohms at GPS frequency.  

Inductor impedance = 2*pi*f*L

This equation is only valid below the self resonant frequency (SRF) of the inductor, so verify that the inductor you choose has an SRF > GPS frequency.


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