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Single-Frequency FM

General Form:
sffm(vo va [fc mdi fs])
Example:
v1 12 0 sffm(0 1m 20k 5 1k)

parameter description default value units
vo offset   volts or amps
va amplitude   volts or amps
fc carrier frequency 1/tstop hz
mdi modulation index 0  
fs signal frequency 1/tstop hz

The shape of the waveform is described by the following equation:

value = vo + va . sin((2$ \pi$ . fc . time) + mdi . sin(2$ \pi$ . fs . time))

This function applies only to transient analysis, where time is the running variable. When referring to default values, tstep is the printing increment and tstop is the final time in transient analysis, see 2.7.10 for explanation.

If this function is used bare and not part of an expression in a voltage or current source, then the general source instance parameters prm1 etc. map as below. It is possible to read and alter these values using the special vector @device[param] construct, or with the alter and sweep commands. However, there is no sanity checking so bad numbers can cause wild behavior or worse.

prm1 vo
prm2 va
prm3 fc
prm4 mdi
prm5 fs


next up previous contents index
Next: Amplitude Modulation Up: Tran Functions Previous: Piecewise Linear   Contents   Index
Stephen R. Whiteley 2019-06-03