Variable Capacitor
Purpose
Variable capacitor.
Library
Nonlinear
Description
This component models a variable capacitor. The capacitance is determined by
the continuous signal fed into the input of the component. The current through a
variable capacitance is determined by the equation

Therefore, the control signal is a vector twice as wide as the width of the component.
It contains both the momentary capacitance values and their derivatives with respect
to time:
. It is the responsibility of the user to
provide the correct derivatives.
Note
- The variable capacitor is based on a current controlled voltage source. It
may therefore not be connected in parallel with other voltage sources or
capacitors.
- The control signal for the momentary capacitance values must be
continuous. Discontinuous changes will produce non-physical results.
Parameters and Dialog Box
-
Width
- The width of the electrical ports resp. the number of variable capacitors
represented by the component.
-
Initial voltage
- The initial voltage of the capacitor at simulation start, in volts
(V). This parameter may either be a scalar or a vector with the width of the
component. The positive pole is marked with a "+". The initial voltage default
is 0.
Probe Signals
-
Capacitor voltage
- The voltage measured across the capacitor. A positive voltage
is measured when the potential at the terminal marked with "+" is greater than
the potential at the unmarked terminal.