Hi all,

I have this setup in hspice.  The box is 4 port s-param of two 50 ohms traces
           ----------------------
inp -----|                          |---- outp
inn -----|                          |---- outn
           ----------------------

vin inp inn ac=1
rout outp outn 100

.ac dec 100 0 10g

When I plot 20*log10(vm(outp,outn)/vm(inp,inn)), the result looks bad.

I tried many other case like vinp inp 0 ac=1,0 and vinn inn 0 ac=1,180 and plot the differential insertion loss.

What did I do wrong?

Thanks,