
1. Re: 3D EM simulation of differential vias with ac coupling capacitors.
rocco_gruschwitz Jun 6, 2016 5:30 AM (in response to 9dc1212fcb898a240100014e727abccf)The ac capacitor adds an open at DC to the signals. Thats why IL starts very low in the negative dB (no energy comes through close to DC) and RL starts close to zero (most of the energy gets reflected close to DC).

2. Re: 3D EM simulation of differential vias with ac coupling capacitors.
9dc1212fcb898a240100014e727abccf Jun 8, 2016 4:36 AM (in response to rocco_gruschwitz)Thanks for the reply.
I have a confusion, capacitor will act as an open circuit in low frequency and short circuit at high frequency, so while extracting in 3D em in port creation wizard , i gave open circuit for capacitors to neglect the creation of ports .
Can you please explain how 3D field solver will take capacitor effects into considerations.

3. Re: 3D EM simulation of differential vias with ac coupling capacitors.
rocco_gruschwitz Jun 8, 2016 7:23 AM (in response to 9dc1212fcb898a240100014e727abccf)The 3d solver in HL9.2 would not take it into consideration. it was one of its limitations. A second step outside of the 3d solver was required in linesim to connect ports on the pads of the capacitor (open in the 3d solver) with a capacitor and extract an s parameter model for the whole linesim schematic.
The new solver in HL 9.3 can use capacitors directly during solve.

4. Re: 3D EM simulation of differential vias with ac coupling capacitors.
9dc1212fcb898a240100014e727abccf Jun 22, 2016 5:26 AM (in response to rocco_gruschwitz)Thanks for the reply
Below is the 3D geometry As said by you
I generated scattering parameters for the above geometry.
scattering parameters generated by above geometry were taken into linesim to introduce the effect of ac coupling capacitors and then i saw insertion and return loss profile
I took capacitor as 100nF and shorted it with resistor od
But whether i take capacitor as 100 nF or remove that capacitor with 0 ohms same graph was observed for return and insertion loss, i think in linesim also it is not taking capacitor into consideration.
Can you help me with this?

5. Re: 3D EM simulation of differential vias with ac coupling capacitors.
rocco_gruschwitz Jun 22, 2016 6:31 AM (in response to 9dc1212fcb898a240100014e727abccf)I would expect the difference only at low frequencies. At DC for example it should look as an open with an IL of very low dB values. RL at DC I would expect close to 0.

6. Re: 3D EM simulation of differential vias with ac coupling capacitors.
9dc1212fcb898a240100014e727abccf Jun 22, 2016 7:33 AM (in response to rocco_gruschwitz)Thanks for the reply
But while taking capacitor value in line sim as 100 nF graphs are same as shorting resistor and taking value as 0hms
Can you please tell where i am lagging.
Thanks

7. Re: 3D EM simulation of differential vias with ac coupling capacitors.
9dc1212fcb898a240100014e727abccf Feb 15, 2017 11:12 PM (in response to 9dc1212fcb898a240100014e727abccf)Is there any procedure in new Hyperlynx v9.4 to add accoupling capacitors. If so can you please guide me to do so.
Thanks
Rahul Ruwali