I have designed a colpitt's oscillator using a bjt npn transistor at 866.5MHz fundamental frequency.When I used a generic transistor model on CircuitMaker 2000,it simulated perfectly with the right frequency,866.5MHz,and self starting...I didnt want to use FETs.My problem is that when I replace the generic model of the transistor to a practical model,example MMBR901 which is supposed to be silicon,Vmax 15 v,Imax 30mA,2.5 Ghz hifreq...it simulates but with a lower frequency!
I googled and did some searching for atleast 2 days before now and am thinking it has something to do with the James Earl effect but not sure.
Anyways,I'd appreciate if someone could tell me whats wrong and why the change as well help me with how to correct it via mathematics and not just trial and error tuning.I have to solder this circuit in the end,so it has to be right.
Thanks
I googled and did some searching for atleast 2 days before now and am thinking it has something to do with the James Earl effect but not sure.
Anyways,I'd appreciate if someone could tell me whats wrong and why the change as well help me with how to correct it via mathematics and not just trial and error tuning.I have to solder this circuit in the end,so it has to be right.
Thanks