TMUX121: IBIS and S-Parameter Models

Hi,

Could you please confirm that the TMUX121 IBIS model is incorrect. 

It would appear that the Con capacitance has been added to the C_comp of the series_switch. According to the IBIS spec "C_comp values are ignored for [Series MOSFET] models", and that appears to be backed up with the Hyperlynx simulation. So currently this IBIS model does not have any Con capacitance modelled at all?

Cheers Dave

Hi David,

Nir will be able to respond to you next week.

Thank you,
Arya

Hello David,

C_comp is the Con capacitance of the mux.
That is how we have it in all of our models. 

Were you able to run the model?
We don't support Hyperlynx, we run our models on ADS.

Thanks,

Nir

According to the IBIS specification "C_comp values are ignored for [Series MOSFET] models". Therefore any capacitance would need to be added using the C_comp of the actual pin models (i.e. TMUX121_SX_3P3V and TMUX121_DX_3P3V), presumably these should have a C_comp value equal approx Con/2 - however these pin models have C_comp set to 0pF)
Do we need a call to try and resolve this rather than message ping-pong

Hello David,

I see what you are saying now.
In the IBIS file, the series switch model has the capacitance value while the terminator is missing it. 

Yes, you are right the model is incorrect. 
As you said there should be an actual C_comp value in the terminator models. 

The TMUX121 has a typical Con of 1.7pF.
You can edit the IBIS file to change the C_comp value to 1pF instead of 0pF. 

Another options is to create an IBIS model using passive components like explained here. 

Thanks,

Nir