Circuit Envelope Simulation in @DS???

[cqmyg5]

:?:
I could't understand the Circuit Envelope Simulation in @DS:

1. Is it equal "transient simulation" plus "frequency analyse"?

2. when i should carry out an Circuit Envelope Simulation?

3. Circuit Envelope Simulation is often used in PA, PLL, GSM System simulation, Why???

 

[toonafishy]

Envelope simulation is used when you want to look at a low frequency signal that is modulated on a high frequency signal. If you use transient simulation on a 1GHz RF signal with 1kHz modulation, you would need very many small time steps to recover the low frequency modulation and it would take a long time. In envelope simulation, you don't sample the RF carrier signal directly but the envelope of the RF carrier to recover the modulation. Its almost like running a transient simulation on the 1kHz directly, which is much faster.

 

[flyhigh]

Yeah, if you are familiar with harmonic balance theory, envelope simulation principles are the analogous - like having harmonic balance with time varying coefitients - this time variations corresponds to the LF modulation of a HF carrier. It is a kind of generalization of HB simulations. I tried to run one in ADS, it was an awfull experience. If you don't know exactly what you are doing do'nt do it! There are a number of options that can influence your results significantly, you have to have theoretical background on this and this is quite a long story.

FlyHigh