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Exponential

General Form:
exp(v1 v2 [td1 tau1 td2 tau2])
Example:
vin 3 0 exp(-4 -1 2ns 30ns 60ns 40ns)

This function can be called as texp to avoid possible conflict with the exp math function.

parameter description default value units
v1 initial value   volts or amps
v2 pulsed value   volts or amps
td1 rise delay time 0.0 seconds
tau1 rise time constant tstep seconds
td2 fall delay time td1 + tstep seconds
tau2 fall time constant tstep seconds

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

time value
0 v1
td1 v1 + (v2- v1)(1 - exp(- (time- td1)/tau1))
td2 v1 + (v2- v1)(1 - exp(- (time- td1)/tau1)) +
  (v1- v2)(1 - exp(- (time- td2)/tau2))

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 2.7.9 for explanation. The argument count is used to distinguish this function from the math function of the same name.


next up previous contents index
Next: Gaussian Random Up: Tran Functions Previous: Tran Functions   Contents   Index
Stephen R. Whiteley 2017-02-22