FreeLists / si-list / [SI-LIST] Re: Why is capacitor with high ESR

["Sogo Hsu" <sogo.hsu@xxxxxxxxxxx>]

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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