.SUBCKT eqvtProbeLoadE5380 %"probeTip" %"GND" # # REV 18 Jun 2002 # # THIS MODEL IS INTENDED FOR SIMULATING THE EQUIVALENT LOAD ON A USER'S # TARGET AND TO SIMULATE THE SIGNAL AT THE LOGIC ANALYZER PROBE TIP. # # BASED ON IN-CIRCUIT MEASUREMENTS MADE WITH 8753E 6GHz NETWORK ANALYZER # accurately models probe load out to >1 GHz # excluding connector resonance (simple C model good to >1GHz) # includes mated-pair connector # includes mfr's recommended pad size over 5mil dialectric Er=4.0 # spice components are equivalent loads, not actual component values # # DOES NOT INCLUDE ANY TRACE STUBS ON TARGET # SINGLE-LINE MODEL ASSUMES ADJACENT PINS ARE GROUNDED # # NOT RECOMMENDED FOR RISETIMES <700pS # connector resonance not modeled (treated as simple C) .param Rtap=121 .param Rtip=20K .param CtipEqvt=0.7p .param Ccon_pads=3.0p # lumped C model of connector and pads Ccon %'probeTip' %'GND' value=Ccon_pads # eqvt circuit of tip isolation network Rtap %'probeTip' %'net1' value=Rtap Ctip %'net1' %'net2' value=CtipEqvt Reqvt %'net2' %'GND' value=60 Rtip %'net1' %'vtrm' value=Rtip Vtrm %'vtrm' %'GND' DC value=0.75 .ENDS eqvtProbeLoadE5380