RLC equivalent circuit in IE3D

[danda821]

HI,

Anyone knows how to use the frequency-dependent RLC equivalent in IE3D. I found the equivalent circuits generated by IE3D is frequency dependent, and many values of R, L or C or Q are negative. Some Q is different from the value I got from equation: Q = f/BW_3dB. Thank you.

 

[jian]

Hi, danda821: The frequency dependent RLC extractions (Pi-network) are completely from fitting. They can be negative. The Q-value defined in Pi-network equivalence is for RFIC design (I think it is -Im(Y110/Re(Y11) and it is for low frequency if I do remember it correctly). It is not the same definition as for antenna applications. Your Q-definition is for band-pass structures for antenna design.

Best regards,

 

[danda821]

Thank you. So how can I use this equivalent circuit file in spice simulator?

 

[jian]

Hi, danda821: Normally, those negative values (mainly C's) are not important. Their values are very small and they can be dropped. They are there because the fitting numerically fits them like that. You normally should simulate a structure at low frequency. Then, you do the PROCESS->LC EQUIVALENT to find the SPICE equivalent circuit. If you select FILE->SAVE SPICE FILE, you can save the equivalent circuit into SPICE format and you can use it on a SPICE simulation.