220 PSPICE Tutorial

220 PSPICE tutorial

DC sweep of a BJT amplifier

We will first go through the steps to build the circuit shown below: (skip this section of you know how)

First place the parts.

1)  Hit hotkey p or from the Menu Place->Part

2)  Enter the name of the part that you wish to add

3)  You will see the menu below. Hit OK

4)  If the part was not in the design cache you would see the menu below this one. Hit <yes> If you should get this menu.

5)  Move your cursor to where you want to place the part. Click your mouse at the location

6)  You will continue to be able to place parts that are of the type that you selected. Hit <esc> to end placing parts.

Below is a list of parts that used to build your schematic along with the libraries that they are in if you are using the school version or student version that you can run at home.

Part / Part name / Library if you are at school / Library if you are using the student version at home
resistor / r / ANALOG
BJT / Q2N2222 / EVAL
DC voltage source / Vdc / SOURCE
current source / Isrc / SOURCE

After placing the parts you should see something like the following:

To move parts:

·  Select the part (or parts) you wish to move with your mouse

·  Drag the part(s) to the new location

To undo: hit ^z

To Copy:

·  Select the part (or parts) you wish to copy with your mouse

·  Hit ^c

·  The object in now in the clipboard

·  If you are writing a laboratory report this clip board is available to Microsoft products. So you can use this command to paste (^v) entire schematics in your reports.

To paste:

·  Hit ^v

·  Move your cursor to where you want to place the object that is in the clipboard

·  Click your cursor at the desired location.

To rotate

·  Select the desire part Hit hotkey r or from the main menu: Edit-> rotate

To mirror (flip) horizontally or vertically

·  Select the desire part. From the main menu: Edit-> mirror

To delete

·  Select the desired portion of the circuit. Hit <delete>

Use these commands to move your parts appropriately. You may have something like the following: Note the current source has been flipped upside down.

To connect the parts use wires. To place wires:

·  Hit hotkey w OR from the tool bar on the right use the place wire icon (third from the top), OR from the main menu: Place->wire

·  Click your mouse where you want the wire to begin.

·  Release the mouse

·  Click the mouse again at a new location to indicate a bend in the wire

·  Double click your mouse at the location when you wish the wire to end

·  Hit <esc> to end the wire command

Naming wires: It is much easier to maintain a design if you name the wires (nets) on your diagram. To do this:

·  From the tool bar on the right use the place net alias (fourth from the top), OR from the main menu: Place->net alias

·  Type the name of the net in the menu that follows

·  Click your curser on the net that you wish to name

·  Hit <esc> to end the place net alias command

Naming ground: A simple way to declare ground is to name the corresponding net with a 0 (zero).

Use the commands that you have learned to connect the parts and label the nets as shown below.

Changing the names of parameters of parts.

Parts are placed with default parameters, for example, resistors default to having a resistance of 1K. To change these parameters. Click on the parameter that you wish to change, for example, for the resistor you would click on 1K. Enter the new value in the resulting menu. Hit <OK>. For the voltage source you would change 0Vdc.

On your schematic

Change the resistor values and the value of the DC voltage source as shown. We will be sweeping the value of the current source so you do not need to change this.

We are just about ready to simulate. We will be sweeping the input current and plotting the output voltage. To save time with plotting. We will place a voltage probe also called a marker on the schematic at Vout (There are also current probes).

To place a probe

·  use the place voltage marker icon at the top of the screen which looks like the probe on the diagram below OR from the main menu: Pspice->Markers->Voltage Level

You are now ready to simulate

To simulate:

1)  From the main menu pspice->new simulation profile

2)  You will see the menu below to the right: Enter the name of a simulation

3)  Hit <create

4)  You will then see the menu below

5)  You need to choose the analysis type. Choose DC Sweep

6)  Select Current source

7)  Enter the Name of the current source that you will be sweeping. Referring to our schematic our was called I1.

8)  Enter the current ranges that you wish to sweep

After you simulation is complete you should see a plot of the output voltage vs input voltage.

If you wish to add additional traces.

·  From your schematic window. Go to Trace->add trace

·  You will see the menu below. From the list on the left you can select a variety of traces. You can also perform functions on them using the macros on the right.

·  Click on a trace that you wish to plot

·  Then hit <OK> to plot it

·  The names are rather straightforward

·  The Base, Collect and Emitter currents of the transistor names Q1 are shown, as are the corresponding voltages.

·  From the schematic window go to trace->delete all traces

·  Then plot the the collector current for your transistor.

·  What do you think betta is? (remember this)

Determining the model of your transistor

·  Close your schematic widow that holds your simulation traces and return to the window with you schematic drawn on it.

·  Select the transistor

·  From the main menu go to edit->Pspice model

·  The betta that you would have for F Active is called Bf the betta that you would have for reverse active is called Br.