agilenthbt

there are many transistor models,but not all can predict intermodulation(such as IMD3) accurately.which model is capable of predicting IMD3 accurately?could anyone please give me suggestion?

most of the new nonlinear models like BSIM3 , or BSIM 4 can predict these effects

but how accurate , this will depend on the accuracy of extraction

khouly

sorry,what I use is GaAs HBT.Bsim is not suitable for this device.

yeah sure , i think the nonlinear models of the BJT can be applied to this , liek MEXTREM , or even the VBIC

khouly

Generally,foundry provides G-P or VBIC model for GaAs HBT. But the measured results show both models can not predict IMD performance accurately. So the design can not be guaranteed especially in designing high linearity amplifier with HBT process. Most of such amplifiers employ predistortion technique, so the model should have the capability of predicting nonlinear performance.G-P or VBIC usually can not model properly the variation of the delay time with current increasing. Agilent HBT model seems to do it,but I'm not sure. Would anyone like to share his/her experience?

i think in big PA comapnies they use thier own technology so they have thier own models which are acuratly model these effects , RFMD and triquent and anadigics all have thier process

khouly

You are right. but in my opinion, without feedback, predistortion has not advantage.
Plz don't complain about the process and the model, just use your idea to control the unknown potential error......

i want to design an hbt amplifier and improve it's prformence by changing device parameter like az doping and width.i will be so approciate if u can give some advice for me.i dont know how i model it.exisitence paper dont have all of parameter information.
regards