3.8  Voltage Controlled Capacitor

3.8.1  Syntax

Device

Gxxxxxxx n+ n– VCCAP nc+ nc– expression
.VCCAP label n+ n– nc+ nc– expression

Model (optional)

.model mname C {args}
.model mname TABLE {args}

3.8.2  Purpose

Voltage controlled capacitor.

3.8.3  Comments

N+ and n– are the positive and negative element (output) nodes, respectively. Nc+ and nc– are the positive and negative controlling nodes, respectively. Value is the transfactor in Farads per volt.

The simulator will faithfully give you a negative capacitor if it seems appropriate. Usually, this part is used with a behavioral modeling function, like PWL, which allows you to specify a table of capacitance vs. voltage.

You may specify the value in any of these forms:
  1. A simple value. This is the capacitance in Farads with 1 volt applied to the control port.

  2. An expression, as described in the behavioral modeling chapter.

  3. A model, as described in the behavioral modeling chapter. The table model describes a table of capacitance vs. control voltage.

3.8.4  Probes

All probes that apply to ordinary capacitors also apply here.