Wednesday, November 11, 2015

TinyLNA part selection

After checking the datasheets, offsetting the board from the center will allow for roughly a 11.9mm x 8.4mm PCB assuming the standard 1.6mm thickness.  I'd like the standard thickness because it's cheaper.

Next it's choosing components.  Using guidance from the LNA4ALL design, I'd like to choose an MMIC which is cheaper and available at Digikey but also has the same package.  I settled on the SPF5043Z from RFMD.

I think it's possible to feed the DC voltage from the USB power right into the output of the MMIC, but I'm not sure how stable that voltage is.  So I'm going to add a provision for a voltage regulator.  It needs to be small, quiet, but able to deliver about 100mA and not generate much heat (since it's small it can't dissipate much).  Which means a linear regulator which is just below the expected input voltage.  I chose the LDK220C40R from ST Micro which outputs 4V.  There's a wide range of other voltages available in the same package/pinout so I can tweak it later if needed.

No comments:

Post a Comment