Envelope Simulation of a FM VCO.

Ali,

Fast envelope cannot be used for oscillators. It's for PAs and transmitters. Standard envelope is the only option, and as you say it isn't always going to be quicker. Are you using harmonic balance mode?

Regards,

Andrew.

Andrew,

Thanks for your response. Yes, I'm using HB mode. My settings are: (Sorry, I couldn't upload a picture of my setup)

Envelop Following Analysis: Classic

Engine: Harmonic Balance (I have nport (s-parameter) in my schematic so shooting mode doesn't work.)

Stop time: 20u. (Is set equal to period of the signal which is modulation the control voltage of the VCO, I set it to 20u to at least capture one period.)

Tones: Frequencies

Oscillator option is checked marked and the related parameters are assigned.

Fast envlp mode: Off

In the user's guide envelop analysis of 2007, I read about "envelope ana for FM signal using speed up method ", but I couldn't find this option.

If you have any other suggestion for the settings or another solution to make this simulation faster please let me know. 

PS. My structure is a VCO with a periodic ramp voltage connected to the control voltage. 

Thanks,

Ali

Not sure why you're reading a 9 year old manual when there are perfectly good current documentation versions which probably reflect the version you're actually using.

There is coverage of FM modulation including the fmspeedup parameter, but I don't believe it is applicable in your case. It's not really for that class of circuit.

If you need more help, please contact customer support because we probably need to see exactly what you're doing - however, I don't think there's anything in envelope analysis which will particularly help in this scenario.

Regards,

Andrew.

Andrew,

Thanks for your help. It seems that I only can use the the fast envelop mode:off or just the transient.

I'm contacted from university, Is there any customer support for the students?

Best,

Ali

Hi Ali,

What University and where are you located?  (Things are handled differently in the EU compared to the US).

In the US, it's typically the department chairperson who is either the liason or knows who the liason is.   The university-Cadence liason can file a Case in Customer Support for you.  The university liason can also get you access to Cadence Online support so you can search relevant Articles, AppNotes, and documentation.

Re:  Shooting Newton envlp

You can use shooting Newton with the nport, provided you set the interpolation method=bbspice on the nport.   You need to be using a recent version of IC (approx 6.1.6 or later) and MMSIM (approx 13.1 or later) tools to have that option.   

 If simulating an oscillator, your only option is "classic" envlp with fast envlp=off

Note that as Andrew mentioned, we would need to see your testcase to determine if envlp is even an option for your circuit.  

best regards,

Tawna

See also 

Andrew

Tawna,

Yes, It's located in US. I would contact the liaison of our department. 

Thanks for the hint for using shooting Newton.

Best,

Ali