Problem 7.2 - The PULSE Waveform and the Unit Step Function
*
* NOTE: This is a three-part problem.
* 1. Use the PULSE waveform function to generate v(t) = u(t).
* 2. Use the PULSE waveform function to generate v(t) = u(t-1).
* 3. Use the PULSE waveform function to generate v(t) = 4.5u(t-2.5).
* For each of the waveforms described above:
* Use the .TRAN command with a time interval 0 < t < 10 seconds.
* Use .PROBE to display a graph of v(t) (the node voltage V(1)).
*
* NOTES ON THE PULSE WAVEFORM: See Appendix A for additional information.
* 1. The PULSE function describes a waveform in terms of an initial
* value, a pulse peak value, rise and fall times, and pulse width.
* 2. The waveform cannot be double-valued. That is, if you omit the
* rise time specification or define the rise or fall time to be
* zero, PSpice will use the value of TSTEP (the first number in the
* .TRAN command statement) as the default rise time.
* 3. If a PULSE waveform has a defined rise and fall time for a given
* circuit simulation, then the defined values must be used. When a
* generic pulse is being used, however, the choice is left to the
* programmer. The usual way is to choose a rise or fall time for
* the PULSE to be much shorter than the shortest time constant in
* the circuit and/or much shorter than the .TRAN analysis period.
* (See Part 3 of the notes on the PWL function, Problem 7.1.)
*
* Part 1 of the program below is complete and ready to run. It is
* given to use as a guide when completing Parts 2 and 3.
*
.OPT NOPAGE
V1 1 0 PULSE(0 1 0 .001) ; This function describes a pulse
; with an initial value of zero, a
; peak value of 1, zero time delay
; after t=0 before the rising edge
; of the pulse starts, and a rise
; time of 1 millisecond.
; The pulse width defaults to the
; .TRAN analysis period if not
; given so the width and fall time
; are omitted.
R1 1 2 1K
R2 2 0 3K
.TRAN .2 10 0 .1 UIC ; This statement defines a printer-plot data
; interval of .2 second (if a printer-plot
; is called for), an analysis interval of
; 10 seconds, zero time delay from t=0 to
; the start of the printer-plot output, and
; a .1 second maximum time step for .PROBE
; graphical data point calculations.
; The UIC statement suppresses the .TRAN
; analysis bias point calculations.
.PROBE
.END
Problem 7.2, Part 2. The PULSE Waveform and the Unit Step Function
*
* Write a PULSE waveform description of the function v(t) = u(t-1).
*
.OPT NOPAGE
V1 1 0 PULSE(0 1 ??????????) ; Complete the PULSE description.
R1 1 2 1K
R2 2 0 3K
.TRAN ??????????????? UIC ; Complete the .TRAN command statement.
.PROBE
*.PLOT TRAN V(1) V(2) ; This is an optional printer-plot command.
; You may use it, delete it, or ignore it.
.END
Problem 7.2, Part 3. The PULSE Waveform and the Unit Step Function
*
* Write a PULSE waveform description of the function v(t) = 4.5u(t-2.5).
*
.OPT NOPAGE
V1 1 0 PULSE(0 4.5 ??????????) ; Complete the PULSE description.
R1 1 2 1K
R2 2 0 3K
.TRAN ???????????????? UIC ; Complete the .TRAN command statement.
.PROBE
.END