| Exponential waveform |
Any independent source can be assigned a time-dependent value for transient analysis. The general form of exponential waveform is:
| EXP ( <V1> <V2> [TDI [TAU1 [TD2 [TAU2]]]] ) |
You must specify a value for the parameters V1 and V2. the remaining parameters, if not specified, assume a default value.
| Parameter | Description | Units | Default |
| V1 | Initial amplitude of the output with respect to the negative terminal (usually ground). | V o A | |
| V2 | Pulsed value. Maximum amplitude of the output swing. | V o A | |
| TD1 | Rise delay time. The point in time, from t0, when the output begins to rise. This provides a phase shift of the output by delaying the start of the exponential waveform. | s | 0 |
| TAU1 | Rise time constant. | s | TSTEP |
| TD2 | Fall delay time. Fall delay time. The point in time, from t0, when the output begins to fall. | s | TD1+TSTEP |
| TAU2 | Fall time constant. | s | TSTEP |
TSTEP is the printing increment and TSTOP is the final time (see the .TRAN control line for explanation).
The waveform value generated by the EXP option is as follows:
| Time | Value |
| 0 to TD1 | V1 |
| TD1 to TD2 | V1 + (V2-V1)*(1-e-(t-TD1)/TAU1) |
| > TD2 | V1 + (V2-V1)*(-e-(t-TD1)/TAU1)+(V1-V2)*(1-e-(t-TD2)/TAU2) |
VIN 3 0 EXP(-4 -1 2NS 30NS 60NS 40NS)