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#### Livpsy

##### Newbie
Hello. I am simulating a vco in cadence and i have simulated the inductor in ads momentum. I dot not which setting's from nport i have to select as when i choose linear hb and hbnoise gives warnings. Also the inductor was simulated from 0 to 120 GHZ with a step of 0.1 GHz

#### BigBoss

##### Advanced Member level 5
Why you have simulated your coil up to 120GHz ? Will the VCO work up to that frequency ??
HB,PSS or Transient simulators don't like Discontinuities therefore they give frequently errors.
Simulate your coil around operating frequency of the VCO and a bit beyond with smaller steps then try again.

#### Livpsy

##### Newbie
How smaller steps.?. And the reason i simulated untill 120 GHz is that when the operational frequency is 40 GHz i want also to see at least 3 harmonics. My step is 100 MHz . Should i set it to 1 MHZ?

#### Livpsy

##### Newbie
Moreover what about the options in nport ?. I choose linear at first and i had many issues. After that i choose rational Which worked but not in all cases.

#### BigBoss

##### Advanced Member level 5
How smaller steps.?. And the reason i simulated untill 120 GHz is that when the operational frequency is 40 GHz i want also to see at least 3 harmonics. My step is 100 MHz . Should i set it to 1 MHZ?
Inductors have Self Resonance Frequencies and beyond this Resonance Frequency , an Inductor behaves like a Capacitor. This is first constraint. So, 3 time of Operating Frequency is-probably- far beyond of its Resonance Frequency.
You shouldn't simulate a Coil beyond this Resonance Frequency because it will create trouble. If a VCO sees a Capacitor instead of an Inductor, it will stop to oscillate. Nonlinear simulators don't have a brain, they are just special purpose calculators.
Simulate 40 GHz around plus-minus-let's say- 2GHz ( I presume VCO Bandwidth has around ) with smaller steps like 1MHz. ( AFS: Adaptive Frequency Sweep, NOT Linear step) . If you attempt to see Nth harmonics, the nonlinearity will supply this information. There is no relationship between EM frequency band and nonlinearity. n-Port should be configured as you said " Linear", other option might be used for different purpose.
Try it and let me know.

#### Livpsy

##### Newbie
What is the difference between adaptive and linear? Secondly, cadence recommends bbspice as interpolation method dor s parameters and not linear

#### BigBoss

##### Advanced Member level 5
What is the difference between adaptive and linear? Secondly, cadence recommends bbspice as interpolation method dor s parameters and not linear
Interpolated method is good if simulated data has sufficiently enough information otherwise interpolation may be
troublesome. All I can say that simulate your coil within a frequency band as narrow as possible to get more data then use those data in Spectre Simulation.