FreeLists / si-list / [SI-LIST] Re: single RLC parameters at a certain frequency

[steve weir <weirsi@xxxxxxxxxx>]

Xuzhengrong, you can understand this by looking at a network of multiple
unique RLGCs. When trying to represent the network with a simpler single
RLGC the values for the most accurate fit depends on what the frequency
band is.

Steve.
xuzhengrong wrote:
> Hi,
> To simplify the model, we often extract single RLGC parameters from the
> s-parameter model at a certain frequency.
> I wonder what on earth the meaning of the single frequency parameters is.
> First, if the parameters only represent the magnitude and phase of the
> S-parameter model at the frequency point, it may have different combinations
> of RLGC to reach the same goal, what's the method or principle?
> Second, if the parameters are meaningful at a certain frequency, why can
> single RLGC parameters often be used to estimate characteristic of package
> model such as IBIS?  
>
> In my opinion, for example, the single RLGC model should be the first-order
> approximation to the real model for transmission line, as Eric's book
> 'Signal Integrity: Simplified' said.
> It is equivalent to the real model within low frequency range and we can use
> it if the signal frequency component is within the range.
> However, if the RLGC model extracted at a certain frequency is only
> meaningful for the extracting frequency, it isn't the first-order
> approximation for the transmission line.
> So we can't use it as the first-order approximation and estimate its low
> frequency characteristic. 
>
>
> Appreciate any idea and discussion for the problem.
>
> Best Regards,
> Zhengrong 
>
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