Islamic University of Gaza Lab #2: Introduction to LTspice

Simulation Faculty of Engineering

Electrical Engineering Department Eng. Nael S. Dokhan

Eng. Malak E. Al-Ashi Electric Circuit Ι Lab (EELE 2110)

LTspice Simulation

SPICE (Simulation Program for Integrated Circuit Engineering) is a powerful general-purpose

analog and mixed-mode circuit simulator that is used to verify circuit designs and to predict the

circuit behavior.

Basic Setup & Getting Started

After opening LTspice, you can start a new schematic or open an existing one. To start a new

schematic, press the new schematic button in the upper left of the window:

Figure 1

Figure 2

Building a Circuit

These are the basic tools on the toolbar along the top of the Schematic Editor. They can all be

accessed with hotkeys which are intuitive for common components: (R) Resistor, (L) Inductor, (C)

Capacitor, (G) Ground and (D) Diode.

Figure 3

Important Default Hotkeys

These are a few of the important default hotkeys that you will use constantly when working in

LTspice.

Figure 4

In this lab we will learn two types of analysis:

1. Dc operation points.

2. Transient analysis.

1. Dc operation points:

We want to analysis the voltage divider circuit shown in Figure 5.

Figure 5

Procedures:

1. Draw the Circuit in Schematic Window as shown in Figure 5.

2. Put V=12v, R1=R2=1kΩ.

3. Go to Simulate →Edit Simulation CMD. Choose the type of analysis you want

to simulate → DC op pnt as shown in Figure 6 then ok.

4. After finished, click on (run) button or go to Simulate>Run to run your

simulation.

5. A simulation showing only the DC operating points as shown in Figure7.

Figure 6

Figure 7

2. Transient analysis

We want to analysis the voltage divider circuit shown in Figure 5.

Note: Here I want the voltage source to be AC voltage (sine wave).

Procedures:

1. Drawing the Circuit in Schematic Window as shown in Figure 5.

2. To get the Ac voltage source right click on voltage then click on the advanced

button as shown in Figure 8.

Figure 8

3. Select the source type (sinusoidal, pulse, piecewise linear etc.) then Edit the sources

as the desired circuit as shown in Figure 9.

Figure 9

4. Run the simulation then choose transient analysis and put the stop time equal 10ms.

Figure 10

5. After running the simulation, the simulation showing the transient analysis will

look like as in Figure 11.

( a )

( b )

Figure 11: waveform and Schematic Window

6. To draw the voltage at any node by using voltage probe cursor, by left click on any

wire to plot the voltage on the waveform viewer.

Figure 12

7. To plot the current passes through any element. You can use the current probe

cursor. By left click on the body of the component.

Figure 13

8. To measure the RMS value for any signal, hold down Ctrl and left click on the I or

V trace label in the waveform viewer.

For example, the RMS value for input signal equal

Figure 14

Exercises:

1. Repeat the circuit in Figure 5 with the two types of analysis.

2. Draw and analyze the two circuits in Figure 15 and Figure 16 with the two

types of analysis. Then fill the following table:

First Circuit:

DC op Point Transient Analysis

V I Average RMS

V I V I

Vin

R1

R2

Second Circuit

DC op Point Transient Analysis

V I Average RMS

V I V I

Vin

R1

R2

R3

Note: For DC Operating point assume Vin=10 V.

For Transient Analysis choose sine wave with amplitude 20V and

Frequency= 5KHz.

Figure 15

Figure 16

The End