Differences

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--- config:netlist [2024/12/04 20:33] – [Netlist configuration options] rajit
+++ config:netlist [2025/05/24 13:27] (current) – [Device generation and parameters] rajit
@@ Line 6: / Line 6: @@
 <code>
-real lambda 0.03e-6
+real lambda 0.3e-6
 </code>
-This is the scale factor used to convert to metric units from the dimensionless transistor sizes. This is normally set to F/2, where F is the feature size.
+This is the scale factor used to convert to metric units from the dimensionless transistor sizes. This is normally set to F/2, where F is the feature size. In this example, we are assuming a 0.6 micron feature size.
 ===== Device generation and parameters =====
@@ Line 97: / Line 96: @@
 real default_load_cap 0
 </code>
-This value (in fF) is added to a node whenever it appears on the RHS of a production rule (per subcircuit). This can be used to "pessimize" your spice simulations to account for wiring capacitance. This can be overridden with the "loadcap=value" attribute in the production rule itself.
+This value (in fF) is added to a node whenever it appears on the RHS of a production rule (per subcircuit). This can be used to "pessimize" your spice simulations to account for wiring capacitance. This can be overridden with the "loadcap=value" attribute in the production rule itself. Since these capacitance values aren't explicit capacitors in the layout, it is convenient to be able to emit a netlist that omits these capacitance values entirely. To do so, the ''ignore_loadcap'' parameter can be set.
+<code>
+int ignore_loadcap 0
+</code>
+Setting it to one will omit the capacitance devices. This option is set by ''prs2net'' when the command-line option ''-l'' is used.
 <code>
@@ Line 129: / Line 132: @@
-===== Transistor device names =====
+===== Transistor devices =====
@@ Line 141: / Line 144: @@
 string nfet_hvt  "nhvt"
 </code>
-The strings above are used for the device names for each transistor type. Note that the device type names are part of the technology-independent ACT configuration.
+The strings above are used for the device names for each transistor type. Note that the device type names are part of the [[config:start#devices|technology-independent ACT configuration]].
+There are a number of parameters that are passed to transistor models that determine the width and length of the device, among other parameters. These parameters have default values that are commonly used for most technologies, but they can be modified using configuration file options. The configuration file options to do so are shown below; in the example, the parameters are set to the default value.
+<code>
+begin fet_params
+   string width "W"
+   string length "L"
+   string fin "NFIN"
+   string area_src "AS"
+   string area_drain "AD"
+   string perim_src "PS"
+   string perim_drain "PD"
+end
+</code>
+For example, the width would be specified using ''W=value'' given the parameters above; changing the ''width'' string will change the parameter name passed to the device model.
+  * ''width'' : width of transistor
+  * ''length'' : length of transistor
+  * ''fin'' : number of fins (used for FinFET nodes)
+  * ''area_src'' : area of the source
+  * ''perim_src'' : perimeter of source
+  * ''area_drain'' : area of drain
+  * ''perim_drain'' : perimeter of drain
 If the FET devices being used are floating-body SOI devices, then their spice representation is not of type "M" (model), but of type "X" (subcircuit). The device has the usual source, gate, drain terminals, but the fourth terminal is no longer bulk, but instead the substrate. All substrate terminals are grounded (as opposed to bulk terminals that are connected to the appropriate supply), so this requires a modified netlist. To have the "svt" device correspond to an SOI-type, use the following: