Interconnect modelling for high speed vlsi

[TGupta]

Hi, I am working on S-Parameter-Based IC Interconnect Transmission Line Characterization by William R. Eisenstadt, Senior Member, IEEE, and YungseonEo.
Here I have designed interconnect using microstrip in ADS momentum and then simulated its S-paramter for 1-10 GHz frequency in order to extract RLGC values.I have extracted the rlgc but they are coming out to be negative which I think is incorrect.So anybody please help me.

 

[biff44]

negative equivalent component values, oddly enough, are not that unusual in modeling. It happens in microstrip models all the time. What is going on is that there are electromagnetic solutions to the circuit, and they have energy stored in various evanescent modes and various phase shifts. To get a simple lumped element model to match the real world, sometimes a negative value is needed to match the curves.

 

[TGupta]

Hi,according to the results given in paper S-Parameter-Based IC Interconnect Transmission Line Characterization by William R. Eisenstadt, Senior Member, IEEE, and YungseonEo.Resistance should increase with frequency but mine is not following it.What could be a reason for that ?