I have a design with Momentum blocks incorporated inside (as 'mom' blocks). All Momentum blocks are simulated up to 300GHz.
However, when running harmonic balance simulation, I get an error: "Can not enforce causality of S parameter for assigned 'fmax' value is equal to or less than the maximal frequency in...." where the rest is the path to the mommdl/text.txt file of the momentum cell view.
The maximal frequency of the HB simulation (100GHz) is far lower than the upprer simulated Momentum frequency (300GHz).
Any ideas on how to solve the problem?
Watch out if you're using the symbol generated by the Momentum interface rather than using an analogLib nport and referencing the s parameter file. From what I've seen recently at customers, the Momentum-generated symbol sets the maximum frequency to be the maximum frequency in the s parameter file, but this defeats the causality correction in spectre. So on the instance, set the maximum frequency to 3 times the value it shows (ie 3 times the frequency you solved up to in Momentum). This is the default value for the underlying nport - unfortunately the momentum symbol doesn't work if you just blank out the max freq in the form.
I've let Agilent know about this (I think I did anyway; I'll check my email when I get into work)
Also, please use MMSIM12.1 to get the latest improvements in spectre's nport component (needed for simulating a parameters)