# S Parameter Inductance and Capacitance Calculations

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#### SrB

##### Newbie level 3 Hello asubraman,

Import or read your S-pareameter file to any simulator (AWR MWO or Sonnet EM)
then plot the Y parameters Then use the following equation to get the Capacitance & Indutance values

Y11 = Im(Y(1,1))

C1=1.0E12 / ( 2 * _PI * _FREQ * ( 1 / Y11 ) )

Where
L1=1.0E9 * ( 1 / Y11 ) / ( 2 * _PI * _FREQ )

L1: Effective Inductance (in nH) of a series RL network

C1: Effective Capacitance (in pF) of a series RC network

_FREQ: is project frequencies in GHz

Note: Sonnet has direct measurement option for the above...

---manju---
Hi Manju

What if I calculate capacitance using Y(2,1) instead of Y(1,1)
C1=1.0E12 / ( 2 * _PI * _FREQ * ( 1 / Y21 ) )

Where
L1=1.0E9 * ( 1 / Y21 ) / ( 2 * _PI * _FREQ )

Will it be same?

#### volker@muehlhaus Here is the math for getting the series components between the ports:

For capacitors
L21 = - imag( 1/ Y21 ) / ( 2 * PI * FREQ )
or for capacitors
C21= 1 / ( 2 * PI * FREQ * imag (1 / Y21) )
or for resistors
R21= -real( 1 / Y21 )

This is valid for 2-port data only (no more ports, no less).

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