guys, bear in mind that the intercept point is primarily a function of
the operating quiescent poit. you cam make it high, really high and get
superlative mixers, even single ended. i designed one aroun the now
defunct VMP4 from Siliconix with an Id of 500mA!!! the damned thing had
nearly +50dB IP#. About the same went with the LNA. All in all 24W
power dissipated in the front end. How many of us can afford that or
need that for the matter?
drop it! what the guy needs is some reasonable value of dynamic range
and around 10-12 dB for IP3. he isn't going to build a radio telescope
receiver on his first attempt. Be reasonable!
with FET's the thing to ensure is that the operating point is
setablished with Vgs set at about half of the pinchoff voltage to
ensure maximum dynamic range. a noise figure under 10dB is adequate for
HF. it's not the galactic noise that limits your reception!
Saandy 4Z5KS