CMETER - Capacitance Meter (Single-Ended IO)

Model Kind

General

Model Sub-Kind

Generic Editor

SPICE Prefix

A

Model Name

CMETER

SPICE Netlist Template Format

@DESIGNATOR %1 %2 @"DESIGNATOR"CMETER
.MODEL @"DESIGNATOR"CMETER cmeter (?gain|gain=@gain|)

Parameters (definable at component level)

The following component-level parameters are definable for this model type and are listed on the Parameters tab of the Sim Model dialog. To access this dialog, simply double-click on the entry for the simulation model link in the Models region of the Component Properties dialog.

Notes

This is a sensing device which is attached to a node in the circuit and produces as an output, a scaled value equal to the total capacitance seen on its input, multiplied by the value assigned to the Gain parameter. This model is useful as a building block for other models, which require to sense a capacitance value and adjust their behavior with respect to it.

The input signal can be either a single-ended current or single-ended voltage signal.

Examples

Consider the capacitance meter in the above image, with the following characteristics:

• Pin1 (input) is connected to net NetC1_2
• Pin2 (output) is connected to net Out
• Designator is U1
• Gain = 10

The entry in the SPICE netlist would be:

*Schematic Netlist:
AU1 NetC1_2 OUT AU1CMETER
.MODEL AU1CMETER cmeter (gain=10)

The effect of the function can be seen in the resultant waveforms obtained by running a transient analysis of the circuit. 

In this example, the following analysis parameters on the Transient/Fourier Analysis page of the Analyses Setup dialog have been used:

• Transient Start Time - set to 0.000
• Transient Stop Time - set to 60.00u
• Transient Step Time - set to 10.00u
• Transient Max Step Time - set to 10.00u

With the exception of the Pulsed Value parameter (set to 4V) and the Period parameter (set to 15us), all other parameters for the Pulse Voltage Source have been left at their defaults.