R: Resistor

Syntax

Rxxxxxxx n+ n- value
Rxxxxxxx n+ n- expression
Rxxxxxxx n+ n- model {L=length} {W=width} {TEMP=temperature}
.RESistor label n+ n- expression

Purpose

Resistor, or general current controlled dissipative element.

Comments

N+ and n- are the positive and negative element nodes, respectively. Value is the resistance in Ohms.

The resistor (type R) differs from the admittance (type Y) in that the resistor is a current controlled element, and the conductance is a voltage controlled element, in addition to the obvious use of conductance ($1/R$) instead of resistance.

You may specify the value in one of three forms:

1. A simple value. This is the resistance in Ohms.

2. An expression, as described in the behavioral modeling chapter. The expression can specify the voltage as a function of current, or the resistance as a function of time.

3. A model, which calculates the resistance as a function of length and width, referencing a .model statement of type R. This is compatible with the Spice-3 ``semiconductor resistor''.

Model statement

A model statement may be used,, with model type R or Res. The parameters are:

RSH = x

Sheet resistance. (Ohms / square). (Required)

CJSW = x

Junction sidewall capacitance. (Farads / meter). (Default = 0.)

DEFW = x

Default width. (meters). (Default = 1e-6)

NARROW = x

Narrowing due to side etching. (meters). (Default = 0.)

TC1 = x

First order temperature coefficient. (Farads / degree C). (Default = 0.)

TC2 = x

Second order temperature coefficient. (Farads / degree C squared). (Default = 0.)

TNOM = x

Parameter measurement temperature. (degrees C.). (Default = 27.)

Resistance is computed by the formula:

resistance = RSH * (L - NARROW) / (W - NARROW)

After the nominal value is calculated, it is adjusted for temperature by the formula:

value *= (1 + TC1 * (T-T0) + TC2 * (T-T0)^2)