Dynamic Float Crosstalk Check (dyn_floatxtalk)
Description
Reports the glitches of high impedance nodes caused by crosstalk of parasitic capacitors in DSPF file. A high impedance state occurs when there is no conducting path from the node to any power supply or ground.
The following device conducting rules are used for the floating node detection:
- MOSFET is conducting if mos region is triode or saturation
- Resistors, controlled resistors, phy_res, relay and inductors are conducting if R<=res_th
- BJT is conducting if Vbe>bjt_vbe OR Ic>bjt_ith
- Diode is conducting if V>diode_vth
- Vsources and iprobes are considered conducting
- Isources, VCCS, and CCCS are conducting if i>isource_ith
- JFET is considered conducting
- Mutual inductors and controlled capacitors are not conducting
- VerilogA: conducting path depends on module details
The results are written to the dynamic.xml file, which can be viewed in a Web browser. This check is supported only with Spectre FX.
Syntax
Name dyn_floatxtalk parameter=value ...
Parameters
Design check parameters
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leaki_times
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[...] sec
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The time point(s) at which the dynamic crosstalk check is performed.
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rise_vth
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0.2
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The threshold of voltage change caused by pulling up of an aggressor. Default is 0.2 V.
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fall_vth
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0.2
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The threshold of voltage change caused by pulling down of an aggressor. Default is 0.2 V.
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cmin
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1.0e-16
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If the lumped capacitance between highZ NET and its aggressor is less than cmin, Caggr<cmin, such aggressor is ignored. Default is 1.0e-16 F.
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capr
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0.2
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If the ratio of between the lumped capacitance and the total capacitor of HighZ NET is less than capr, Caggr/Ctotal<capr, such aggressor is ignored. Default is 0.2.
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error_limit
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10000
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Maximum number of errors reported. Default is 10000.
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Floating node detection parameters
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mos_ith
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100E-9
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Mosfet ids conducting threshold for high impedance node detection. Default is 100 nA.
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mos_gds
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1.0E-5
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Mosfet gds conducting threshold for floating node detection. Default is 1e-5.
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bjt_vbe
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0.4
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BJT vbe conducting threshold for floating node detection. Default is 0.4 V.
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bjt_ith
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50E-9
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BJT ic conducting threshold for floating node detection. Default is 50 nA.
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res_th_va
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10E6
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VerilogA resistor conducting threshold for high impedance node detection. Only applicable on AMS IE element and on one or two port AHDL module. Default is 10MOhms.
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res_th
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1E12
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Resistor conducting threshold for floating node detection. Default is 1 TOhm.
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diode_vth
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0.6
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Diode voltage conducting threshold for high impedance node detection. Default is 0.6V.
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isource_ith
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1.0E-12
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Current source conducting threshold for floating node detection. Default is 1 pA.
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mos_conduct_rule
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tri_sat
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The conducting rule to decide if a mosfet is on. Use tri_sat for triode or saturation region based rule. Use tri_sat_sub for triode or saturation or subthreshold region based rule. Use ids_gds for ids>mos_ith or gds>mos_gds rule. Use vgs for vgs>vth rule (Only supported in XPS Fastspice). Possible values are tri_sat, tri_sat_sub, ids_gds, and vgs. Default is tri_sat..Possible values are vgs, ids_gds, tri_sat and tri_sat_sub.
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Floating node detection filtering parameters
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node
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[...]
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Nodes to which the floating node detection is applied. Default is all( node=* ).
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xnode
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[...]
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Nodes to be excluded from the floating node detection. Default is none.
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inst
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[...]
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Subcircuit instances to which the floating node detection is applied. Default includes all instances (inst=*).
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xinst
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[...]
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Subcircuit instances to be excluded from the floating node detection. Default is none.
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subckt
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[...]
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The instances of the specified subcircuit to which the floating node detection is applied. Default includes all subcircuits (subckt=*).
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xsubckt
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[...]
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The instances of the specified subcircuits that are excluded from the floating node detection. Default is none.
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