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A few questions about inductors simulation with HFSS (Read 8727 times)
Yutao Liu
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A few questions about inductors simulation with HFSS
Feb 26th, 2009, 7:36pm
 
hello everybody,

I want to model and to analyze inductors with HFSS. I found that the poly layer was not added when I read some examples. Why? Is the simulation more accurate after adding the poly layer?

And is it appropriate to only add those shield metal layers under the inductor,when I want to simulate the floating shield inductor which is some metal layers are added underneath the inductor? Is there anything else I should set up due to the shield metal layers?

thanks!
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pancho_hideboo
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Re: A few questions about inductors simulation with HFSS
Reply #1 - Feb 27th, 2009, 7:31pm
 
Yutao Liu wrote on Feb 26th, 2009, 7:36pm:
I want to model and to analyze inductors with HFSS.
I found that the poly layer was not added when I read some examples. Why?
Is the simulation more accurate after adding the poly layer?
I can't understand a meaning of your question.

Is Poly Layer used in your inductor structure ?
Just Poly Layer isn't used in inductors of examples you saw, is it ?

Yutao Liu wrote on Feb 26th, 2009, 7:36pm:
And is it appropriate to only add those shield metal layers under the inductor,when I want to simulate the floating shield inductor which is some metal layers are added underneath the inductor?
I can't understand a meaning of your question.

What do you refer as "those" ?
Is there any relation with Poly Layer ?
If your process have only two metal and one poly, you have to use poly layer as shield layer.

Yutao Liu wrote on Feb 26th, 2009, 7:36pm:
Is there anything else I should set up due to the shield metal layers?
No one except for you knows process profile(layer profile) you use.

This is also true for your another question. No one except for you knows your specific situations.
http://www.designers-guide.org/Forum/YaBB.pl?num=1231747377/0#0

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Yutao Liu
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Re: A few questions about inductors simulation with HFSS
Reply #2 - Mar 1st, 2009, 7:04pm
 
Thanks for pancho_hideboo's replying!

I am new with HFSS, so i don't quite understand the settings such as boundarier and terminals in HFSS.

pancho_hideboo wrote on Feb 27th, 2009, 7:31pm:
Is Poly Layer used in your inductor structure ?
Just Poly Layer isn't used in inductors of examples you saw, is it ?

Yes, poly layer was not used in inductors of the example I mentioned.  So, the poly layer should be omitted in the model due to its absence in the inductor structure?

pancho_hideboo wrote on Feb 27th, 2009, 7:31pm:
What do you refer as "those" ?
Is there any relation with Poly Layer ?
If your process have only two metal and one poly, you have to use poly layer as shield layer.

There are 1 poly layer and 6 metal layers in the process i use, and i use the metals as floating shield layers rather than the poly.

I actually want to know whether HFSS would take the shield layers into account when analyzing when these shield layers is "floating", that is, they aren't connected to any terminals or "ground" and they are not connected to the spiral inductor.

Furthermore, the floating shield layers are used to limit the effect from eddy current formed in the substrate. Can HFSS take the eddy current into account during calculation by default? If it can't, how should i do?
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pancho_hideboo
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Re: A few questions about inductors simulation with HFSS
Reply #3 - Mar 2nd, 2009, 5:42am
 
Yutao Liu wrote on Mar 1st, 2009, 7:04pm:
I am new with HFSS, so i don't quite understand the settings such as boundarier and terminals in HFSS.
If you want someone to understand your questions, you have to describe your questions regarding situation and condition in detail using industrial standard terminologies.

Yutao Liu wrote on Mar 1st, 2009, 7:04pm:
Yes, poly layer was not used in inductors of the example I mentioned.  
So, the poly layer should be omitted in the model due to its absence in the inductor structure?
If you don't include objects made by poly layer inside your analysis area, poly layer is naturally unused.

Yutao Liu wrote on Mar 1st, 2009, 7:04pm:
I actually want to know whether HFSS would take the shield layers into account when analyzing when these shield layers is "floating", that is, they aren't connected to any terminals or "ground" and they are not connected to the spiral inductor.
Of course, Ansoft HFSS can taka such effects into account since it is Full-Wave Analysis by FEM.

Yutao Liu wrote on Mar 1st, 2009, 7:04pm:
Can HFSS take the eddy current into account during calculation by default?
Of course, Ansoft HFSS can taka such effects into account since it is Full-Wave Analysis by FEM.

I can't understand why you are confusing.
There is no special problem at all in your situation.
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« Last Edit: Mar 2nd, 2009, 6:44am by pancho_hideboo »  
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Yutao Liu
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Re: A few questions about inductors simulation with HFSS
Reply #4 - Mar 4th, 2009, 4:40am
 
pancho_hideboo wrote on Mar 2nd, 2009, 5:42am:
Yutao Liu wrote on Mar 1st, 2009, 7:04pm:
Can HFSS take the eddy current into account during calculation by default?
Of course, Ansoft HFSS can taka such effects into account since it is Full-Wave Analysis by FEM.

I can't understand why you are confusing.
There is no special problem at all in your situation.

I am confusing because I am not sure which types of boundaries I should assign.
Should I draw a new rectangle covering the bottom face of substrate and assign it as "Perfect E" boundary?
I doubt about this assignment because I want to model a lossy substrate.
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pancho_hideboo
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Re: A few questions about inductors simulation with HFSS
Reply #5 - Mar 4th, 2009, 4:53am
 
Yutao Liu wrote on Mar 4th, 2009, 4:40am:
Should I draw a new rectangle covering the bottom face of substrate and assign it as "Perfect E" boundary?
No. If you use perfect electrical wall boundary, it must be far from substrate, here an area between substrate and perfect electrical wall is air.
You can also use perfect magnetic wall.
If your substrate thickness is enough large, you might be able to omit air.

Also you can set radiation, absorption, periodically boundary conditions.

Mathematically these boundary conditions are well-known
Dirichlet boundary condition, Neumann boundary condition, Mixed boundary condition, Sommerfeld radiation condition, etc...

You should read text book about electric magnetic theory and then manuals of Ansoft HFSS.
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« Last Edit: Mar 4th, 2009, 7:39am by pancho_hideboo »  
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Yutao Liu
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Re: A few questions about inductors simulation with HFSS
Reply #6 - Mar 5th, 2009, 4:17am
 
pancho_hideboo wrote on Mar 4th, 2009, 4:53am:
You should read text book about electric magnetic theory and then manuals of Ansoft HFSS.

I'm a student for analog/RF circuit design, so I am not quite familiar with microwave design, especially modeling passive component in HFSS.
I just want the equivalent circuit of a floating shielded inductor to do my circuit design.
Is there any other better ways to achieve my goal?
Or, which text books about electric magnetic theory is suitable to me?
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