AC simulation of spiral inductor with schematic

First I made a layout of single ended spiral inductor and ran simulation, from which I got .s2p and .ds s-parameter files. Now I have to make schematic of it for AC simulation to get inductance and Q factor. Can you help me with the schematic? OR if it will be ok if I insert equations of L and Q in layout simulation window rather than doing AC simulation with schematic?

Do you want to calculate the L and Q values from S-parameters, or create a complete equivalent circuit model?

Calculate L and Q:

Open a new data display and add the template shown below:

Equivalent circuit model:

If you need accurate results over a narrow bandwidth only, you can use the equivalent series L and R at the operating frequency.

If you need a wideband model, and this is an RFIC inductor on silicon substrate, you can try my automated modelling tool:

http://muehlhaus.com/products/equivalent-circuit-model-fit-for-rfic-inductors:Dr. Mühlhaus Consulting & Software GmbH » Automated Circuit Model Fit for RFIC inductors

This reads the *.s2p file and creates a wideband inductor circuit model almost automatically. Limitation: The model is valid for silicon substrates onbly (SiGe, CMOS) and doesn't work for GaAs or PCB.

Thank you so much.

Actually I am using ADS 2015.01. In that automated circuit model fit for RFIC inductor is not available. I have tried the template. I have made series R L circuit using s parameter file and using equations I got some results. Can you tell me whether my way is correct or wrong?ignore the frequency range here.

I have attached my schematic and results. Also the results I got from template is different than this.

Hello again,

correct, my RFIC inductor model fit tool requires ADS 2016 or later.

Your setup with AC source and 5 Ohm resistor is unexpected. The usual way to extract L and Q is from S/Y/Z-parameter simulation.

You need to decide if you want the inductor parameters for single ended or differential operation, as I described in this appnote:

http://muehlhaus.com/support/ads-application-notes/inductor-em-ports:Dr. Mühlhaus Consulting & Software GmbH » Inductor EM simulation: 1-port or 2-port?

You mentioned single ended, so we can use Z parameters for evaluation. You can create Z-parameters from Momentum results by using a schematic simulation and choosing Z parameters output in the simulation controller, but there is an easier way: in the data display, add equation Z=stoz(S). This will calculate Z parameters from S parameters of your dataset. Then, add equations Q1port = imag(Z)/real(Z) and R1port=real(Z) and L1port = imag(Z)/(2*pi*indep(S))

Good luck!

Volker

Thank you so much!!

Thank you for your help till now!

I have tried to extract L and Q from s parameter equations. But I am getting negative values. I have results of 14 inductor simulations....all results are negative. I used these equations:

Z=stoz(S)

L=imag(z(1,2))/(2*pi*freq)

R= real(z(1,2))

Q=imag(z(1,2))/real(z(1,2))

I have attached my schematic here.

Your equation with Z21 is wrong.

To get familiar with model extraction, and test your equations, use a known inductor model circuit with known series and shunt values.

Hello!
Thank you but can you tell me how these equations with z(1,2) are wrong? Because in some of the documents I found the same equations. If these are wrong then what are the correct equations? And I don't have known inductor model circuit.

Just remember what Z21 is: Z21 = V2/I1 with I2=0 (port 2 open). So your equation is valid for shunt inductor to ground, not for series inductor.

If you want to extract the series path, excluding shunt parasitics like pad capacitance to ground, use Lser = -1/imag(Y21), Rser = -1/real(Y21)

Also have a look at the documents I linked above.

Inductor model: depends on your inductor technology, so please decide yourself. If you need full service, my company provides that as a service. Here in the forum, I can only give some directions, but not solve everything for you.

Good luck!

Volker

OK.

Thank you!

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