[SI-LIST] Re: Effective impedance of a uniformly loaded bus

Thank You!

> -----Original Message-----
> From: steve weir [mailto:weirsi@xxxxxxxxxx]
> Sent: Tuesday, November 29, 2005 12:14 AM
> To: Edi Fraiman; si-list@xxxxxxxxxxxxx
> Subject: Re: [SI-LIST] Re: Effective impedance of a uniformly loaded
bus
>=20
> Edi, was Dr. Johnson's explanation sufficient?
>=20
> My message was thatat you clearly understand the C' formula.  But,
when it
> comes to line impedance, discontinuities are what disturb signal
quality,
> not the line length.
>=20
> But, well past the era of TTL, I think this is mostly academic.  For
any
> modern rise time, work the coefficients and I think you will find that
> manipulating the segment lengths will not make the difference between
a
> design that is viable and one that is not.
>=20
> Steve.
> At 06:09 PM 11/28/2005 +0200, Edi Fraiman wrote:
> >Steve,
> >
> >Could you please clarify?
> >
> >Edi=3D20
> >
> > > -----Original Message-----
> > > From: steve weir [mailto:weirsi@xxxxxxxxxx]
> > > Sent: Monday, November 28, 2005 4:49 PM
> > > To: Edi Fraiman; si-list@xxxxxxxxxxxxx
> > > Subject: Re: [SI-LIST] Effective impedance of a uniformly loaded
bus
> > >=3D20
> > > Edi, your understanding of C' is fine, but your conclusion is not
> >quite
> > > right.  Think in terms of impedance continuity.
> > >=3D20
> > > Steve.
> > >=3D20
> > > At 09:01 AM 11/28/2005 +0200, Edi Fraiman wrote:
> > > >Hello experts,
> > > >
> > > >I have question regarding formula C'=3D3D3D Cline + NCload/length
and =3D
> >Z'
> >=3D3D3D
> > > >(L/C')^1/2 ("A Handbook of Black Magic" Paragraph 4.4.3.1).
> > > >
> > > >If I design trace with several loads than according to the
formula I
> >can
> > > >conclude next statement:
> > > >Longest trace cause of reducing in total capacitance C' and
increase
> >the
> > > >Z'.
> > > >
> > > >So, long trace help to driver drive loads (impedance is larger).
> > > >I fill confuse, everyone knows that long trace is not good for
SI.
> > > >=3D3D20
> > > >Could you please clear me this issue?
> > > >
> > > >  =3D3D20
> > > >
> > > >Best Regards,
> > > >
> > > >Edi Fraiman
> > >
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> > >=3D20
> >
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>=20

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