(C) Capacitor Statement

Capacitors in PLECS Spice support initial conditions, temperature dependence, and parasitic series/parallel resistances. Furthermore, nonlinear capacitors with user-defined charge functions are supported.

Linear Capacitor

Recommended

Cname pos neg capacitance <IC=ic> <TC1=tc1> <TC2=tc2> <TEMP=temp> <M=m>

Cname pos neg modelName <capacitance> <L=l> <W=w> <IC=ic> <TC1=tc1> <TC2=tc2> <TEMP=temp> <M=m>
.MODEL modelName C <NAME=value ...>

Legacy

Cname pos neg capacitance <IC=ic> <TC=tc1<,tc2>> <TEMP=temp> <M=m>

Cname pos neg modelName <capacitance> <L=l> <W=w> <IC=ic> <TC=tc1<,tc2>> <TEMP=temp> <M=m>
Cname pos neg <capacitance> modelName <L=l> <W=w> <IC=ic> <TC=tc1<,tc2>> <TEMP=temp> <M=m>
.MODEL modelName C <NAME=value ...>

The TC instance parameter is followed by one or two temperature coefficients. Internally, we map these values onto TC1 and TC2.

The device type C must be specified in the model statement.
The capacitance can also be set as the model parameter CAP. If it’s defined in both the model and the instance, the instance value is used.
You can customize this model by providing a list of model parameter (name-value format) at the end of the .MODEL statement.

Instance Parameters

Parameter	Description	Default Value
IC	Initial voltage across the capacitor	none
TC1	Temperature coefficient for CAP (first order correction)	\(0\,^\circ\text{C}^{-1}\)
TC2	Temperature coefficient for CAP (second order correction)	\(0\,^\circ\text{C}^{-2}\)
TEMP	Device temperature	\(27\,^\circ\text{C}\)
M	Number of parallel devices	\(1\)
L	Length of the semiconductor capacitor	\(0\, \text{m}\)
W	Width of the semiconductor capacitor	DEFW

The default value for L is not permitted. Thus, a nonzero value must be set either in the instance statement or as a model parameter.

Model Parameters

Parameter	Description	Default Value
T_ABS	Device temperature	\(27\,^\circ\text{C}\)
CAP	Capacitance	\(0\, \text{F}\)
CJ	Bottom junction capacitance	\(0\, \text{F}/\text{m}^2\)
CJSW	Sidewall junction capacitance	\(0\, \text{F}/\text{m}\)
DEFW	Default width of the semiconductor capacitor	\(10^{-6}\, \text{m}\)
NARROW	Narrowing due to the etching process	\(0\, \text{m}\)

You can specify the instance parameters TC1, TC2, L, and W as model parameters too. If both are provided, the instance values take priority.
The instance parameter TEMP overwrites the model parameter T_ABS.
When the capacitance is specified either in the instance statement or through the parameter CAP, the parameters L, W, CJ, CJSW, DEFW, and NARROW are ignored.
The parameters CAP, CJ, and CJSW are temperature-corrected using TC1 and TC2.

Linear Capacitor with Parasitic Elements

PLECS Spice supports a model of a linear capacitor with equivalent series resistance (RSER) and an additional resistance (RPAR) connected in parallel with the series combination of the ideal capacitor and the series resistor.

Recommended

Cname pos neg capacitance <M=m> <RSER=rser> <RPAR=rpar>

Legacy

Cname pos neg modelName <capacitance> <L=l> <W=w> <TC1=tc1> <TC2=tc2> <TEMP=temp> <M=m> <RSER=rser> <RPAR=rpar>
Cname pos neg modelName <capacitance> <L=l> <W=w> <TC=tc1<,tc2>> <TEMP=temp> <M=m> <RSER=rser> <RPAR=rpar>
.MODEL modelName C <NAME=value ...>

We support all the instance and model parameters defined above with the exception of IC.

Instance Parameters

Parameter	Description	Default Value
M	Number of parallel devices	\(1\)
RSER	Series resistance	\(0\,\Omega\)
RPAR	Parallel resistance	\(+\infty\,\Omega\)

Note

Initial conditions are not supported for linear capacitors with parasitic elements.

Charge-based Capacitor

Recommended

Cname pos neg Q={function body}

Legacy

Cname pos neg Q=function body
Cname pos neg Q={5*x}; Equivalent to: Cname pos neg Q={5*V(pos,neg)}

If exactly one = is included, everything to the right of = is treated as function body.
Unless defined as parameter, x is replaced by the voltage across the capacitor.

Examples

Csnub n1 n2 100n
Cesr n3 n4 10u RSER=0.01
Cvar n5 n6 Q={1e-9*V(n5,n6)*(1+0.1*V(n5,n6)^2)}