How to simulate a multi micostripe coupling

[zionico90]

Hi guys,

i should try to estimate, in first approximation the capacitance between several conductor in a flex cable. This simplification is helpful because i must evaluate, with a 3D software, the induced noise into only 2 specific conductors. Therefore, when the signal is fast in terms of rise/fall time, the computation time is too high and for this reason i think to simplify the problem with a system in which there are 2 wire connected by a total capacitance in order to taking into account the shielding contribution of the other conductors. The cross section of the cable is shown in the attachment; my question is: which is the correct theoretical method to calculate the capacitance between pin #16 and #23?Are there other methods to simplify the structure?

thank you.

N.B the conductors are rectangular like a microstrips

 

[FvM]

The shielding effect of the other conductors is essential, also the isolator geometry and embedding medium (air?).

The other conductors can be possibly treated as a single ground shape, depending on the connected impedance.

 

[zionico90]

Yes, the shielding effect is very important. The insulator layer is a small thickness of kapton and the emebedded medium is air.
The inpout impedance is 300ohm and the output is higher than 1kohm.

 

[FvM]

You have to determine, if the other lines can be considered as shorted to ground or if the divided voltage must be taken into account. The other point is that the simple electrostatic (pure capacitive coupling) model is only appropriate for the lower MHz range, depending on the conductor length. At higher frequencies, transmission line effects become effective.

 

[zionico90]

The frequency range is 70Khz-1Mhz and the conductors length is 100mm. Maybe in these condition the simple electrostatic model is valid; what do you think? Other simplification are possibile?