questions about model files and simulator

[trashbox]

Hi..How are you? I want to design a 2.4G LC-VCO based PLL as an interest (no tape out).So I have several questions about model files and simulator.
1) There are inductor,varator and resistance in my circuit. If I want to simulate this circuit, Must the model file include inductor,varator and resistance parameters besides PMOS NMOS parameters?
2) If I use mixed-mode files(not RF process model and there are only PMOS and NMOS parameters in my model) to simulate my circuit, what will the simulator do? The simulator will act the inductors,varators as ideal component?
3) How to get free RF model files as practice?

4) What is the difference between HSPICE and SpectreRF(or @DS)? In my company,HSPICE the main simulator.but I know SpectreRF(or @DS) is the dominant simulator in RFIC. At a word, HSPICE is not suitable for what frequency range?

Thank you very much.

 

[radiohead]

1+2. About the passive components: you can be sure that if no particular model is specified, the simulator will treat them as ideal. But for more complicated devices (diodes, varactors, ...) there is no such thing as an ideal model. Only a good, quick and simple model and a better model that need more simulation time. The simple model will need less parameters to be filled in. But these need to be specified. How else do you define the capacitance-voltage relationship for different varactors?
4.HSpice is a time domain simulator, but a very efficient one. SpectreRF/ADS can more simulation types than HSpice. For RF designers, it is a common practice to design in the frequency domain instead of time domain. SPectreRF/ADS offer such extensions. So, it's not about the operating frequency. It's about the simulation type.

 

[goodboy_pl]

for such RFIC blocks, u must have onchip capacitors (MIM for example), Inductors and resistors (specially if they are non linear like NWELL), and varactors.
if u have not them, then the simulation results with ideal models or predicted ones can understimate tuning range and phase noise.
HSPICE can not simulate phase noise, for this reason most of the designers work with specttre or @DS which can do that by Harmonic Balance simulation.
since the device dimentions for oscillators are very small (respect to other blocks like LNA and PA) it is possible to use mixed mode model; also the models for RF transistors in design kits are only for large transistors maybe due to difficalty in accurate measurment!

BEST!

 

[raymond_luo2003]

Hi, rightnow the HSPICE offer new feature so call" HspiceRF" which has the hamornic balance engine same as @ds. The HSPICE RF is not commercially ready now, but you can contact your local synopsys FAE to get the latest information incase your company do only ahve the HSPICE.

Raymond

 

[mit80]

For the model of the passive element, it depends on specific technology. For the resistor, such as poly resistor , most of the CMOS process have its own model. ( Of course you can still use the ideal one) for inductor, only some technology with sth like RF option cantain model in it. and they have some limitation suchas inductance value or Q value.