CMETERR - Capacitance Meter (Differential IO)

Model Kind

General

Model Sub-Kind

Generic Editor

SPICE Prefix

A

Model Name

CMETER

SPICE Netlist Template Format

@DESIGNATOR %%vd(%1,%2) %%vd(%3,%4) @"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 differential current or differential voltage signal.

Examples

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

• Pin1 (positive input) is connected to net In1
• Pin2 (negative input) is connected to net In2
• Pin3 (positive output) is connected to net Out
• Pin4 (negative output) is connected to net GND
• Designator is U1
• Gain = 5

The entry in the SPICE netlist would be:

*Schematic Netlist:
AU1 %vd(IN1,IN2) %vd(OUT,0) AU1CMETER
.MODEL AU1CMETER cmeter (gain=5)

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 50.00m
• Transient Step Time - set to 200.0u
• Transient Max Step Time - set to 200.0u