The capacitor model contains process information that may be used to compute the capacitance from strictly geometric information.

The capacitor has a capacitance computed as:

If value is specified on the instance line then

[\begin{array}{ll} {C_{nom} = {{{\lbrack font\ rm\ \lbrack char\ v\ mathalpha\rbrack\lbrack char\ a\ mathalpha\rbrack\lbrack char\ l\ mathalpha\rbrack\lbrack char\ u\ mathalpha\rbrack\lbrack char\ e\ mathalpha\rbrack\rbrack} \cdot {\lbrack font\ rm\ \lbrack char\ s\ mathalpha\rbrack\lbrack char\ c\ mathalpha\rbrack\lbrack char\ a\ mathalpha\rbrack\lbrack char\ l\ mathalpha\rbrack\lbrack char\ e\ mathalpha\rbrack\rbrack}} \cdot m}} & \ \end{array}]

If model capacitance is specified then

[\begin{array}{ll} {C_{nom} = {{{\lbrack font\ rm\ \lbrack char\ C\ mathalpha\rbrack\lbrack char\ A\ mathalpha\rbrack\lbrack char\ P\ mathalpha\rbrack\rbrack} \cdot {\lbrack font\ rm\ \lbrack char\ s\ mathalpha\rbrack\lbrack char\ c\ mathalpha\rbrack\lbrack char\ a\ mathalpha\rbrack\lbrack char\ l\ mathalpha\rbrack\lbrack char\ e\ mathalpha\rbrack\rbrack}} \cdot m}} & \ \end{array}]

If neither value nor CAP are specified, then geometrical and physical parameters are take into account:

[\begin{array}{ll} {{\lbrack font\ rm\ \lbrack sub\ \lbrack char\ C\ mathalpha\rbrack\ \lbrack char\ 0\ mathalpha\rbrack\rbrack\rbrack} = {\lbrack font\ rm\ \lbrack char\ C\ mathalpha\rbrack\lbrack char\ J\ mathalpha\rbrack\rbrack}\left( {l - {\lbrack font\ rm\ \lbrack char\ S\ mathalpha\rbrack\lbrack char\ H\ mathalpha\rbrack\lbrack char\ O\ mathalpha\rbrack\lbrack char\ R\ mathalpha\rbrack\lbrack char\ T\ mathalpha\rbrack\rbrack}} \right)\left( {w - {\lbrack font\ rm\ \lbrack char\ N\ mathalpha\rbrack\lbrack char\ A\ mathalpha\rbrack\lbrack char\ R\ mathalpha\rbrack\lbrack char\ R\ mathalpha\rbrack\lbrack char\ O\ mathalpha\rbrack\lbrack char\ W\ mathalpha\rbrack\rbrack}} \right) + 2{\lbrack font\ rm\ \lbrack char\ C\ mathalpha\rbrack\lbrack char\ J\ mathalpha\rbrack\lbrack char\ S\ mathalpha\rbrack\lbrack char\ W\ mathalpha\rbrack\rbrack}\left( {l - {\lbrack font\ rm\ \lbrack char\ S\ mathalpha\rbrack\lbrack char\ H\ mathalpha\rbrack\lbrack char\ O\ mathalpha\rbrack\lbrack char\ R\ mathalpha\rbrack\lbrack char\ T\ mathalpha\rbrack\rbrack} + w - {\lbrack font\ rm\ \lbrack char\ N\ mathalpha\rbrack\lbrack char\ A\ mathalpha\rbrack\lbrack char\ R\ mathalpha\rbrack\lbrack char\ R\ mathalpha\rbrack\lbrack char\ O\ mathalpha\rbrack\lbrack char\ W\ mathalpha\rbrack\rbrack}} \right)} & \ \end{array}]

CJ can be explicitly given on the .model line or calculated by physical parameters. When CJ is not given, is calculated as:

If THICK is not zero:

[\begin{array}{ll} \begin{array}{ll} {{\lbrack font\ rm\ \lbrack char\ C\ mathalpha\rbrack\lbrack char\ J\ mathalpha\rbrack\rbrack} = \frac{{\lbrack font\ rm\ \lbrack char\ D\ mathalpha\rbrack\lbrack char\ I\ mathalpha\rbrack\rbrack}\varepsilon_{0}}{\lbrack font\ rm\ \lbrack char\ T\ mathalpha\rbrack\lbrack char\ H\ mathalpha\rbrack\lbrack char\ I\ mathalpha\rbrack\lbrack char\ C\ mathalpha\rbrack\lbrack char\ K\ mathalpha\rbrack\rbrack}} & {if DI is specified,} \ & \ {{\lbrack font\ rm\ \lbrack char\ C\ mathalpha\rbrack\lbrack char\ J\ mathalpha\rbrack\rbrack} = \frac{\varepsilon_{SiO_{2}}}{\lbrack font\ rm\ \lbrack char\ T\ mathalpha\rbrack\lbrack char\ H\ mathalpha\rbrack\lbrack char\ I\ mathalpha\rbrack\lbrack char\ C\ mathalpha\rbrack\lbrack char\ K\ mathalpha\rbrack\rbrack}} & {otherwise.} \ \end{array} & \ \end{array}]

If the relative dielectric constant is not specified the one for SiO2 is used. The values of the constants are: (\varepsilon_{0} = 8.854214871e - 12\frac{F}{m}) and (\varepsilon_{SiO_{2}} = 3.4531479969e - 11\frac{F}{m}). The nominal capacitance is then computed as:

[\begin{array}{ll} {C_{nom} = {C_{0}{\lbrack font\ rm\ \lbrack char\ s\ mathalpha\rbrack\lbrack char\ c\ mathalpha\rbrack\lbrack char\ a\ mathalpha\rbrack\lbrack char\ l\ mathalpha\rbrack\lbrack char\ e\ mathalpha\rbrack\rbrack} m}} & \ \end{array}]

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

[\begin{array}{ll} {C\left( T \right) = C\left( {\lbrack font\ rm\ \lbrack char\ T\ mathalpha\rbrack\lbrack char\ N\ mathalpha\rbrack\lbrack char\ O\ mathalpha\rbrack\lbrack char\ M\ mathalpha\rbrack\rbrack} \right)\left( 1 + TC_{1}\left( {T - {\lbrack font\ rm\ \lbrack char\ T\ mathalpha\rbrack\lbrack char\ N\ mathalpha\rbrack\lbrack char\ O\ mathalpha\rbrack\lbrack char\ M\ mathalpha\rbrack\rbrack}} \right) + TC_{2}\left( T - {\lbrack font\ rm\ \lbrack char\ T\ mathalpha\rbrack\lbrack char\ N\ mathalpha\rbrack\lbrack char\ O\ mathalpha\rbrack\lbrack char\ M\ mathalpha\rbrack\rbrack})^{2} \right) \right.} & \ \end{array}]

where (C\left( {\lbrack font\ rm\ \lbrack char\ T\ mathalpha\rbrack\lbrack char\ N\ mathalpha\rbrack\lbrack char\ O\ mathalpha\rbrack\lbrack char\ M\ mathalpha\rbrack\rbrack} \right) = C_{nom}).

In the above formula, `(T)' represents the instance temperature, which can be explicitly set using the temp keyword or calculated using the circuit temperature and dtemp, if present.