[SI-LIST] Re: Why is capacitor with high ESR
- From: "Sogo Hsu" <sogo.hsu@xxxxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Fri, 03 Dec 2004 09:43:45 -0000
Zhangkun,
Yes, I understand "ABC" in FDTD algorithm. But, "absorbing" is not
equal to "impedance matching". Simply speaking, radial transmission
line is a 2D transmission line. The radial impedance is proportional
to the reciprocal od distance. If your goal is to get resonance
free, I suggest you can adopt "Adaptive Voltage Positioning"
algorithm. It is easy to implement.
Best regards,
Sogo Hsu, Ph. D.
Simulation center/Foxconn
--- In si-list@xxxxxxxxxxxxxxx, Zhangkun <zhang_kun@xxxx> wrote:
> Sogo
>
> I have read the paper long long ago : ) That paper gives rise to
my method and Istvan also give me a lot of help and instruct.
>
> It is possible to match the impedance of radial transmission line.
In FDTD algorithm, there is one absorbing boundary condition named
Mur's. My method is similar to that. I have made testing board and
compared simulation and measurement.
>
> Best Regards
>
> Zhangkun
> 2004.12.3
> ----- Original Message -----
> From: "Sogo Hsu" <sogo.hsu@xxxx>
> To: <si-list@xxxx>
> Sent: Friday, December 03, 2004 4:14 PM
> Subject: [SI-LIST] Re: Why is capacitor with high ESR
>
>
> >
> > Zhangkun,
> >
> > Several years ago, I also tried to "match" the impedance.
Ideally,
> > it is possible, however, it is hard to "match" the
characteristic
> > impedance of "radial transmission line". Besides, you can find
the
> > related paper in IEEE. "Reducing simultaneous switching noise
and
> > EMI on ground/power planes by dissipative edge termination" by
Novak.
> >
> > Best regards,
> >
> > Sogo Hsu, Ph. D.
> >
> > Simulation center/Foxconn
> >
> > --- In si-list@xxxxxxxxxxxxxxx, zhangkun 29902 <zhang_kun@xxxx>
> > wrote:
> > > Dear ALL
> > >
> > > I am incharge of power integrity(PI) and electromagnetic
inference
> > (EMI) in Huawei Tech. In printed circuit board(PCB), the power
> > ground plane pair composes of one resonant cavity, which could
be
> > studied by means of 2-dimension tansmission line theory.
> > >
> > > According to the transmission line theory, when the
transmission
> > line is matched, there is no resonance. At the edge of PCB, the
EM
> > energy is reflected because the transmission line is OPEN.
> > Traditional decoupling capacitors are of low ESR, which could
not
> > damping the resonance. Therefore I need capacitor with high ESR,
> > whose ESR should be matched with the transmission line. On the
other
> > hand, the ESL is critical at high frequency. The ESL should be
as
> > small as possible. The package of capacitor mainly determines
ESL so
> > that the package should be as small as possible, such as 0402 or
> > 0603. The capacitance should be as large as possible so that
some
> > benifit could be gotten at lower freqeuncy domain.
> > >
> > > In DesignCon 2005, Cadence and Huawei will present one paper
on
> > this topic. The measurement results showed that the power ground
> > noise is reduced about 10db and the far field EMI is reduced
about
> > 5db at several hundred MHz, when the capacitor of high ESR is
> > applied. The frequency domain is extended to 1GHz where all the
> > power ground noise and far field EMI could be reduced.
> > >
> > > Best Regards
> > >
> > > Zhangkun
> > > 2004.12.3
> > >
> > >
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