cap_var :
A variable capacitor circuit element.

The cap_var primitive represents a two-terminal capacitor of which capacitance varies with the voltage across the two terminals, pos and neg.

The parameter C is a real-typed array defining the voltage-dependent capacitance as a piecewise-constant (PWC) function using the following coefficients:

 '{C0, V1, C1, V2, C2, V3, C3, ..., VN}.

meaning that the resistance C is:

C = C0     for V < V1,
    C1     for V1 <= V < V2,
    C2     for V2 <= V < V3,
    ...
    C(N-1) for V(N-1) <= V < VN.
    CN     for VN <= V

Note that the array has an odd number of elements since it starts with a capacitance value (C0) and ends with a capacitance value (CN). The piecewise-constant capacitance means that the capacitor has a piecewise-linear Q-V relationship.

Note that this primitive is a pseudo-module to describe a structural netlist of electrical circuits and not a behavioral model by itself. The XMODEL simulator extracts an event-driven behavioral model at run-time based on the circuit network described by these circuit-level pseudo-modules.

Input/Output Terminals

Name	I/O	Type	Description
pos	input	xreal	positive terminal
neg	input	xreal	negative terminal

Parameters

Name	Type	Default	Unit	Description
C	real array	‘{1.0}	farads	PWC capacitance
ic	real	`NaN	volts	initial condition
Cpos	real	0.0	farads	pos-to-gnd capacitance
Cneg	real	0.0	farads	neg-to-gnd capacitance