.FOUR |

Fourier Analysis of Transient Analysis Output

The simulator can perform a Fourier analysis based on the last cycle of transient data that is calculated during a Transient analysis.

.FOUR <freq> <out_var1> [out_var]* |

freq

Is the fundamental frequency.

out_var

Represent the output variables that specify the voltages and currents for which you want the spectral components.

The Fourier analysis is performed over the interval (TSTOP-period, TSTOP), where TSTOP is the final time specified for the transient analysis, and period is one period of the fundamental frequency. The dc component and the first nine harmonics are determined. For maximum accuracy, TMAX (see the .TRAN line) should be set to period/100.0 (or less for very high-Q circuits).

```
.FOUR 100K V(5)
.FOUR 20MEG V(2) (V(3)-V(4))
```