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balajisu Post subject: lumped filter design on ADS Posted: Mon Jul
17, 2006 4:24 pm Captain Joined: Wed Jul 06, 2005
5:54 pm Posts: 24 Location: Germantown,MD Hi group,
Designed a lumped element filter using the Filter design guide in
ADS. I would like to replace the ideal components with the vendor library
components. What are the important parameters/issues that I need to
take care of while selecting the replacement components. Any suggestions
will be really appreciated. regards Balaji Top
IR Post subject: Posted: Wed Jul 19, 2006 11:11 am
Site Admin Joined: Mon Jun 27, 2005 2:02 pm Posts:
373 Location: Germany Hello, The most important parameter
that you should consider is the Q. For inductors it is more critical
since their Q is smaller and when they are connected in parallel with
capacitors their lower Q prevails (Exactly the same as connecting 2
resistors in parallel). There are models available for inductors and
capacitors which include Q data for capacitors (Murata) and inductors
(You can find good models in Coilcraft website). _________________
Best regards, - IR Top languer Post subject:
Posted: Wed Jul 19, 2006 4:36 pm Captain Joined:
Sun May 14, 2006 8:53 pm Posts: 17 Location: Earth After Q,
as IR metioned, I would also add resonant frequency. This one will normally
affect more the bigger component values and will de-tune your circuit.
Resonant frequency will tell you when a capacitor stops behaving as
a capacitor and looks more like and inductor (or the opposite in the
case of inductors). As a rule-of-thumb, Q will make the filter
more lossy and SRF (series resonant frequency - note there is also parallel
resonant frequency) will limit the usable frequency range of the components.
Top IR Post subject: Posted: Thu Jul 20, 2006 1:29
pm Site Admin Joined: Mon Jun 27, 2005 2:02 pm
Posts: 373 Location: Germany Languer is right, as long as the
ADS allows you to enter the SRF as a parameter. I don't remember if
this is possible. _________________ Best regards, -
IR Top balajisu Post subject: Posted: Tue Jul
25, 2006 11:27 am Captain Joined: Wed Jul 06, 2005
5:54 pm Posts: 24 Location: Germantown,MD thanks for your
valuable comments. Can I consider SRF to be the self resonant frequency
of inductor or capacitor or Is this term different from series resonant
(or parallel resonance) I have made the response look more like
what I intended to do except for the loss part. I guess I need to get
better Q inductors and try retuning the circuit for required performance.
Top IR Post subject: Posted: Tue Jul 25, 2006 11:52
am Site Admin Joined: Mon Jun 27, 2005 2:02 pm
Posts: 373 Location: Germany The inductor model includes SRF
which is a parallel resonance frequency - this is the capacitance of
the inductor winds. The capacitor model includes SRF which is serial.
So if you have the information per the device you are using just add
it for the ADS simulation. As you mentioned, Q will affect the insertion
loss of the filter. More information: Inductor Model:
https://www.intusoft.com/articles/inductor.pdf Capacitor
model: https://www.ecircuitcenter.com/Circuits/ ... model1.htm
Good luck! _________________ Best regards, - IR
Top balajisu Post subject: Posted: Wed Jul 26, 2006
8:54 am Captain Joined: Wed Jul 06, 2005 5:54 pm
Posts: 24 Location: Germantown,MD Hi Thanks for the links.
If i'm using Vendor models(coilcraft, vishay or AVX) in ADS
do I still need to add the SRF component to get the right results.
Balaji Top IR Post subject: Posted: Wed
Jul 26, 2006 9:16 am Site Admin Joined: Mon Jun 27,
2005 2:02 pm Posts: 373 Location: Germany Hello, You
are welcome! If the models contain the SRF value, and the ADS
allows you to enter this value then you should use it. Good luck!
_________________ Best regards, - IR Top
balajisu Post subject: Posted: Wed Jul 26, 2006 11:53 am
Captain Joined: Wed Jul 06, 2005 5:54 pm Posts:
24 Location: Germantown,MD Hi I do have a datasheet that
provides SRF value for the models but looks like ADS doesn't let me
add the SRF value to the component. I guess I just need to assume that
the model uses the SRF value. Is there anyway around this? Thanks
for your time Balaji Top IR Post subject:
Posted: Wed Jul 26, 2006 3:46 pm Site Admin Joined:
Mon Jun 27, 2005 2:02 pm Posts: 373 Location: Germany The
ADS will use the parasitic capacitance value to calculate the SRF for
an inductor and the parasitic inductance for capacitor to calculate
the same. These calculations are formulas built in the model.
_________________ Best regards, - IR
Posted 11/12/2012
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