The general form of the instance of a resistor is the following:

R<name> <node1(+)> <node2(-)> [value] [model name] [L=<length>] [W=<width>] [TEMP=<device temperature>] [TC=<tc1> [,<tc2>]]

For standard resistors:

R<name> <node1(+)> <node2(-)> <value> [model name] [TEMP=<device temperature>] [TC=<tc1> [,<tc2>]]

For semiconductor resistors:

R<name> <node1(+)> <node2(-)> <model name> L=<length> [W=<width>]

For nonlinear resistors:

R<name> <node1(+)> <node2(-)> R=<expression>



Is the name of the component and the initial letter R identifies the resistors.

node1, node2

The first node (node1) is defined as positive. The voltage across the component is therefore defined as the first node voltage minus the second node voltage. Current flow from the first node through the component to the second node is considered positive.


Is the resistance (in ohms) and may be positive or negative but not zero. If this parameter is omitted, then the resistance may be calculated from the process information (RSH and NARROW) in the model and the given length and width.

model name

The model can be omitted if the resistance value is specified while must always be specified together with the length for the semiconductor resistors.


Diffusion length in meters. Must always be specified together with the model for semiconductor resistors.


Diffusion width in meters. Must be specified for the semiconductor resistors. If width is not specified, then it is taken from the default width (DEFW) given in the model.


Nonlinear resistors can be generated by putting the expression directly on the element line. The expressions may be any function of voltages and currents through voltage sources in the system. In an AC analysis, only the DC component of a voltage or current source when the initial operating point was calculated is used. In a transient analysis, any voltages or currents are evaluated at each time point. See also Behavioral modeling expressions.


The (optional) TEMP value is the temperature at which this device is to operate. This value, if specified, takes precedence over the analysis temperature.


The term TC must be specified only when you want to assign a value to one or both of the temperature coefficients tc1 (coefficient of first order) and tc2 (coefficient of second order) measured in parts per degree centigrade. tc1 is the linear temperature coefficient and is sometimes given in data sheets as parts per million per °C. To convert ppm specs to TC1 divide by 1E6.

Note Note

The use of the term TC is obsolete and is used for compatibility with the syntax of SPICE2. To specify a value for the temperature coefficient is preferable to use a model and assign a value to the parameters TC1 and TC2.


R1 1 2 1K
R2 1 2 1K RMOD
R3 1 2 RMOD 1K
R4 1 2 1K TC=0.001
R5 1 2 RMOD L=50u W=5u
R6 1 2 R=1000+V(node1)*5

See also

Resistor model
Resistor instance parameters