50 ohm feedlines for SOC's
 

hello,

50 ohm is the standard port impedance.for 2.4GHz and an Fr4 substrate
of say 4.2 dielectric constant and 1.6mm height, the computed/simulated
Zo from ADS2004a line calc, is equivalent to about 3.12mm. also, for
traces less than 1/20 of the guided wavelength, matching is not
necessary.

the question is this, most of the RFIC's or SOC's usually employ RF
feedlines at 2.4GHz lower than the 3.12 mm computed. for one, a Sige
2.4GHz amplifier RFin and RFout port is about .62 mm and the fact that
the trace extends greater than 1/20 or 1/10 of the guided
wavelength...or is it because they used a different substrate of higher
dielectric???

thanks