So far you have mostly used SPICE's standard voltage sources with a few waveforms like constant, sinusoidal and pulse. In the last part of this tutorial lesson, you will use [[RF.Spice]]'s "'''Nonlinear Controlled Source'''" to synthesize more complex waveforms. For example, your input signal to the PWM modulator in the previous part was a periodic sinusoid. In this part, you will use a time-limited sinusoid with a finite duration of 8ns. You can make this waveform by multiplying the original sinusoid by a one-shot pulse of the same duration. The latter can be defined as a pulse waveform with an extremely large period:
<table>
<tr>
<td>
{| border="0"
|-
| valign="top"|
|-
{| class="wikitable"
|+ VS
|-
! scope="row"| Offset Voltage
| 0
|-
! scope="row"| Peak Amplitude
| 5
|-
! scope="row"| Frequency
| 1k
|-
! scope="row"| Delay Time
| 0
|-
! scope="row"| Damping Factor
| 0
|}
</td>
<td>
<p> </p>
</td>
<td>
{| border="0"
|-
| valign="top"|
|-
{| class="wikitable"
|+ VC
|-
! scope="row"| Initial Voltage
| 0
|-
! scope="row"| Peak Voltage
| 1
|-
! scope="row"| Delay Time
| 0
|-
! scope="row"| Rise Time
| 1p
|-
! scope="row"| Fall Time
| 1p
|-
! scope="row"| Pulse Width
| 1m
|-
! scope="row"| Pulse Period
| 3m
|}
</td>
</tr>
</table>
<table>