Dynamic Floating Gate Induced Leakage Check (dyn_floatdcpath)

Spectre Syntax

title dyn_floatdcpath net=[n1 n2 ...] <leaki_times=[t1 t2 …]> ith=<value> error_limit=<value> <save=no|violation> <spice=no|yes> <detailed_path=[yes|per_fm|per_fn]> <sort=[no|current]> res_th_va=<value> res_th=<value> isource_ith=<value> bjt_vbe=<value> bjt_ith=<value> diode_vth=<value> <floatgate=[yes|no|gate_has_driver_no_cap]> node=[n1 n2...] xnode=[n1 n2...] <inst=[inst1 inst2...]> <xinst=[xinst1 xinst2...]> <subckt=[subckt1 subckt2....]> <xsubckt=[xsubckt1 xsubckt2....]> 

SPICE Syntax

.cck title dyn_floatdcpath net=[n1 n2 ...] <leaki_times=[t1 t2 …]> ith=<value> error_limit=<value> <save=no|violation> <spice=no|yes> <detailed_path=[yes|per_fm|per_fn]> <sort=[no|current]> res_th_va=<value> res_th=<value> isource_ith=<value> bjt_vbe=<value> bjt_ith=<value> diode_vth=<value> <floatgate=[yes|no|gate_has_driver_no_cap]> node=[n1 n2...] xnode=[n1 n2...] <inst=[inst1 inst2...]> <xinst=[xinst1 xinst2...]> <subckt=[subckt1 subckt2....]> <xsubckt=[xsubckt1 xsubckt2....]>

Description

Reports the DC leakage paths that are caused by floating gate. The check based on leakage analysis is evoked when parameter leaki_times is specified. leaki_times should be carefully selected in standby or power-down mode. The check is performed for a transient simulation at the time points specified by leaki_times.

Worst leakage paths caused by floating gate MOSFET devices are estimated and reported. The leakage paths are checked between the specified power supply nodes (net).

The floating node detection and path detection in the leakage analysis-based method comprises of two steps.

Step 1: Floating node detection

This stage is like dyn_higz check. A node is considered floating (or in high impedance state) if it has no conducting path to a power supply or ground. A report of all MOSFETs with floating gates can be printed by using the parameter floatgate. The following device conducting rules are used for floating node detection:

• A MOSFET is considered to be conducting if region is either triode or saturation.
• Resistors, controlled resistors, phy_res, relay, and inductors are considered to be conducting if R<= res_th.
• A BJT is considered to be conducting if vbe>bjt_vbe or ic>bjt_ith.
• A diode is considered to be conducting if v>diode_vth.
• Vsource, and iprobes are considered to be conducting.
• Isources, VCCS, and CCCS are considered to be conducting if i>isource_ith.
• A JFET is considered to be conducting.
• Mutual inductors and controlled capacitors are considered to be non-conducting.
• In Verilog-A, conducting path depends on module details

Step 2: Current path detection

In the violation report of dyn_floatdcpath, the current is not from a transient simulation, but from the estimation of a worst scenario and the purpose is to trigger the violations.

The current path detection is like dyn_dcpath. If more than two nets are specified, Spectre checks the leakage path between each pair of nets. For example, if net=[vdc1 vdc2 0], the conducting path between vdc1 and vdc2, vdc1 and 0, and vdc2 and 0 is checked.

Arguments

General Parameters
leaki_times	Times at which the check is performed.
error_limit	Maximum number of errors to be reported. Default is 10000.
save	Specifies how to probe the signals specified within this circuit check. Possible values are: no: None of the signals in this circuit check are probed. This is the default value. violation: Automatically probe the signals with violations under this circuit check.
spice	Specifies whether to save the probed signals specified by the save parameter in the SPICE syntax. Possible values are: yes: Saves the signals in SPICE syntax no: Saves the signals in Spectre syntax. This is the default value.
Path Detection Parameters
net	Hierarchical node names between which the leakage path is checked. Wildcards are not allowed. All combination of nets are checked. Default is none.
ith	Leakage paths more than ith to be reported. The default value is 50uA.
Path Detection Filtering Parameters
detailed_path	Specifies how to print the path. Possible values are: yes: Prints the detailed path. per_fm: Prints one path per floating MOSFET. This is the default value. per_fn: Print one path per floating node. This value is not supported in Spectre FastSPICE.
sort	Specifies how to sort the violations. Possible values are: no: No sorting is done. This is the default value. current: dyn_floatdcpath sorts the violations based on maximum current.
Floating Node Detection Parameters
bjt_vbe	BJT vbe conducting threshold for high impedance node detection. BJT is conducting if i>bjt_ith or vbe>bjt_vbe. Default is 0.4V.
bjt_ith	BJT ith conducting threshold for high impedance node detection. BJT is conducting if i>bjt_ith or vbe>bjt_vbe. Default is 50nA.
res_th_va	Verilog-A resistor conducting threshold for high impedance node detection. This parameter is applicable only on AMS ie element, and on one or two-port AHDL module. Default is 10 MOhms.
res_th	Resistor conducting threshold for high impedance node detection. Resistor is conducting if R<res_th. Default is 1TOhms.
diode_vth	Diode voltage conducting threshold for high impedance node detection. Diode is conducting if v>diode_vth. Default is 0.6V.
isource_ith	Current source conducting threshold for floating node detection. Current sources are conducting if i>isource_ith. Default is 1pA.
Floating Node Detection Filtering Parameters
floatgate	Specifies whether to report all MOSFETs with floating gate at specified leaki_times. Possible values are: gate_has_driver_no_moscap: Floating MOSCAPs are not reported. yes: All MOSFETs with floating gates at the specified leaki_times are reported. no: The report is not generated. This is the default.
node	Nodes to which the floating node detection is applied. Default is node=*.
xnode	Nodes that are excluded from floating node detection. Default is none.
inst	Subcircuit instances to which the circuit check is applied. Default is inst=*.
xinst	Subcircuit instances that are excluded from the circuit check. Default is none.
subckt	Instances of the specified subcircuit to which the circuit checks are applied. Default is subckt=*.
xsubckt	Instances of the specified subcircuit which are excluded from the circuit checks. Default is none.

Example

dyn1 dyn_floatdcpath net=[vdd1 0] leaki_times=[7.5n]

This example reports the high impedance node induced DC leakage paths between the nets vdd1 and 0 at the specified leaki times based on leakage analysis. This examples displays the following report in the Web browser.

The report contains the following three sections:

• The first section shows the From Net vdd To Net 0 between which the path is found.
• The second section shows the actual instances in the path. The first column Instance shows instances in the path. The second column Current (A) shows the current through the instances. The third column Floating Gate Node establishes the link between the floating gate node and MOSFET. The third column may contain either a node name or N/A. If it contains a node name, it means that the corresponding element is a MOSFET whose gate is floating. The fourth column shows the voltage of the floating gate.
• The third section shows the state of MOSFETs in the path. It does not report anything other than MOSFET. The first column Device is the MOSFET name. The second column Model shows the model name. The remaining columns show the terminal names and voltages.

Related Topics

Dynamic Checks

Return to top