| Frequency-modulated waveform |
Any independent source can be assigned a time-dependent value for transient analysis. The general form of frequency-modulated waveform is:
| SFFM ( <VO> <VA> [FC [MDI [FS [PHASEC [PHASES]]]]] ) |
You must specify a value for the parameters VO and VA. the remaining parameters, if not specified, assume a default value.
| Parameter | Description | Units | Default |
| VO | DC offset voltage or current. Used to adjust the DC bias of the signal generator with respect to the negative terminal (usually ground). | V o A | |
| VA | Peak amplitude. | V o A | |
| FC | Carrier frequency. | Hz | 1/TSTOP |
| MDI | Modulation index. Value corresponding to a function of amplitude of the modulating signal indicating the level of modulation. MDI=(frequency deviation)/FS. | 0 | |
| FS | Signal frequency. | Hz | 1/TSTOP |
| PHASEC | Carrier phase. | degree | 0 |
| PHASES | Signal phase. | degree | 0 |
TSTOP is the final time (see the .TRAN control line for explanation).
The waveform value generated by the SFFM option is as follows:
VO + VA * sin((2∏*FC*t+PHC)+MDI*sin(2∏*FS*t+PHS))
PHC = PHASEC in radiants; PHS = PHASES in radiants.
V1 12 0 SFFM(0 1M 20K 5 1K)