kelly
|
Hi RFICDUDE and Aaron,
Thanks for replying. Sorry , I didn't make it clear, in oder to have LO of 17dBm, I do need to use the thick oxide devices that can tolerate a voltage up 2.5V across the oxide.
When I use the qpss and qpac to get my IIP3 plot, I have the same problem as Aaron posted before, i.e., the 3order slope looks weired at low input level. Since my IIP3 is around 20dBm, my slope starts to act funny below 0 dBm. I did use the conservative setting for running qpss, but it didn't seem to change my results that much. In general, the slope seem to look ok for the top 20 dB input range. In another word, if the IIP3 is 25dBm, then the 3 order slope starts to behave funny below 5 dBm. So if you try to extrapolate the IIP3 at Pin < 5dBm, you get pretty lousy number, not to mention the slope looks all wrong.
Do you guys think this is a simulation/modeling problem? Or in reality, the IIP3 is that bad at the low input level?
Thanks much. Kelly
|