## [SI-LIST] Re: Resonant Modes

• From: xuzhengrong <xuzhengrong@xxxxxxxxxx>
• To: weirsi@xxxxxxxxxx
• Date: Wed, 29 Aug 2007 16:26:36 +0800

``` Steve,
papers
issued on DesignCon.
I know  increasing ESR and decreasing inductance can lower  Qs  which
decreases the resonance and makes the impedance  smooth.
What I meant is that, for the same plane pair structure with the same
capacitors,  when I set the number of modes and simulate,  I will get =
datas
of  different mode such as Mode 1, Mode2 and so on.
According to the figure of the result, it seems that Mode 1 shows the
resonance from  horizontal angle,  Mode 2 from vertical angle, Mode 3 =
from
diagonal angle, etc. Different mode analyzes the resonance from =
different
angle.
As my last mail  said,  every mode has a certain frequency and Q =
increases
with the number of modes and corresponding frequency in term of the =
result.
Mode 1 is the lowest frequency among all.  Therefore,  with the =
increasement
of the number of modes,  more resonant frequency will appear.
You mean,  I only pay attention to the bandwidth of significant signal =
which
may excite the resonance. Ok, I see.

My following question is, why do Qs increase with the number of modes =
and
frequency  for the same cavity and PDN?
Which imformation will I obtain  from Qs?=20
For Q indicates the ratio of  storage and loss,  does it mean larger =
number
of Mode with higher resonant frequency will let more energy pass?

Best  Regards
Zhengrong Xu

=B7=A2=BC=FE=C8=CB: si-list-bounce@xxxxxxxxxxxxx =
[mailto:si-list-bounce@xxxxxxxxxxxxx]
=B4=FA=B1=ED steve weir
=B7=A2=CB=CD=CA=B1=BC=E4: 2007=C4=EA8=D4=C229=C8=D5 14:02
=CA=D5=BC=FE=C8=CB: xuzhengrong@xxxxxxxxxx
=D6=F7=CC=E2: [SI-LIST] Re: Resonant Modes

Zhengrong,

Pay attention to the resonances that are within the bandwidth of =
significant

Q depends on the capacitors and materials you use for your PCB. Low =
mounted
inductance capacitors such as X2Ys exhibit lower Qs than capacitors with
higher mounted inductances and similar ESRs.

Cavities that are thinner and/or have higher tangent losses exhibit =
lower Qs
than do thicker cavities and/or cavities with lower tangent loss.

At the end of the day you are always fighting inductance in your =
capacitors
and interconnect. You can manipulate modes and Q by manipulating your
capacitors and cavity geometries.

Steve.

xuzhengrong wrote:
> Oh, I am so sorry for that.=3D20
> I have sent another email in text format,  but i don't know why it =3D =

> hasn't been sent to all yet.
> When I sent to  si-list@xxxxxxxxxxxxx,  i received several autoreplies =

> =3D for their out of office.=3D20 So I sent  both to =
si-list@xxxxxxxxxxxxx=20
> and =3D si-list-bounce@xxxxxxxxxxxxx this time.
> I'm new here and very glad to join in.=3D20 Could you tell me the=20
> relationship between si-list@xxxxxxxxxxxxx and=20
> si-list-bounce@xxxxxxxxxxxxx? When i want to join the discussion,=20
> which =3D mail address will i send to?
>
> Thank you for your reminder with  best regards.=3D20 My question is=20
> listed as follows.
>
>
> Hi all,
> I am new in using EM tools to analyze the plane pairs' resonance.
> After inputing the number of modes and computing, the results have =3D =

> several values including freqency and Q. Every mode has a certain=20
> frequency and =3D Q increases with the number of modes.=3D20 =3D20 =
Which=20
> mode should i pay most attention to?
> Why does Q value increase with the number of modes and frequency?
> How to analysze with these data and which information can i obtain=20
> from =3D it?
> =3D20
> Appreciate any idea about that.
> =3D20
> Best Regards
> Zhengrong Xu
>
>
>
> =3DB7=3DA2=3DBC=3DFE=3DC8=3DCB: olaney@xxxxxxxx =
[mailto:olaney@xxxxxxxx]=3D20
> =3DB7=3DA2=3DCB=3DCD=3DCA=3DB1=3DBC=3DE4: =
2007=3DC4=3DEA8=3DD4=3DC229=3DC8=3DD5 12:00
> =3DCA=3DD5=3DBC=3DFE=3DC8=3DCB: xuzhengrong@xxxxxxxxxx
> =3DD6=3DF7=3DCC=3DE2: Re: [SI-LIST] Resonant Modes
>
> Just so you know what I actually received...
> I think jpg files need to be sent as attachments.
>
> On Wed, 29 Aug 2007 11:02:59 +0800 xuzhengrong =
<xuzhengrong@xxxxxxxxxx>
> writes:
>  =20
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--=20
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