[SI-LIST] Re: Open/Short Circuit Impedance of the board
- From: "Hassan O. Ali" <hassan@xxxxxxxx>
- To: <r_shirsat@xxxxxxxxxxx>
- Date: Thu, 16 Sep 2004 10:59:14 -0400 (EDT)
Assume the network in question is made up of one series inductance element
followed by
one shunt capacitance element (closer to the load). Now, if the load is
short-circuited,
the whole network will be represented by the series inductance element. That
is, the
input impedance Zsc = jwL (the impedance of the series inductance element).
When the
load is open-circuited, the network will actually be represented by the
inductance
element in SERIES with the capacitance element. That is, the input impedance
Zoc = jwL +
1/jwC. If Zsc and Zoc are known, L and C can be computed.
In most high-speed applications, however, the networks are distributed. That
is, the
network is actually a connection of a multitude of the above-described LC
networks. If
an entire distributed network is represented by one LC network, then the "L"
is,
strictly speaking, the "effective inductance" and the "C" is the "effective
capacitance".
When you have conduction and and dielectric losses, then the series resitance
(R) and
shunt conductance (G) will also come into the equations.
Hope that helps.
Hassan.
On Sep 16, "Craig Clewell" <cclewell@xxxxxxxxx> wrote:
>
> Rohan,
>
> Without knowing anything else about what you are reading it sounds like
> they are referring to the capacitance and inductance. If you were to
> short the end of the line and measure you get the inductance, and if you
> open the end of the line you get the capacitance. These values can be
> read from the smith chart at low frequencies by looking at the S11
> measurement provided that the line is shorter than lambda/4.
>
> Craig
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
> On Behalf Of Rohan Shirsat
> Sent: Thursday, September 16, 2004 5:26 AM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Open/Short Circuit Impedance of the board
>
>
> Hi All,
>
> I was going thru Sigrity tutorial and there was a section on Open/Short
> Circuit Impedance of the board. Can some1 explain in brief what that
> means.
>
> Cheers
> Rohan R Shirsat
> Intel Corp
> ICPE CDTG Power Delivery
>
> +91-80-25075861
> rohan.r.shirsat@xxxxxxxxx[1]
>
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