Simple amplifier spice simulation

In the previous article we described SPICE simulation types and explained DC analysis, AC analysis, and transient analysis among the four types of analysis functions provided as standard. In this article, we explain the remaining function, Monte Carlo simulations. Monte Carlo is a general term for methods using random numbers in simulations and numerical calculations. Nearly all the components used to create actual circuits--resistors, capacitors, inductors, diodes, transistors, ICs, and so on--have characteristics with variations.

We are searching data for your request:

Simple amplifier spice simulation

Wait the end of the search in all databases.
Upon completion, a link will appear to access the found materials.

Content:

• Build an Op Amp SPICE Model from Its Datasheet – Part 1
• Spice Simulation Application Circuits
• Simulators
• POWER AMPLIFIERS & AND THEIR SIMULATIONS
• Subscribe to RSS
• Types of SPICE simulation: Monte Carlo
• Spice Amplifier Tutorial using (.DC, .OP, .AC, .TRAN, .FOUR, .SUBCKT)
• PartSim Circuit Simulator
• Power Amplifiers
• PCB Design & Analysis

WATCH RELATED VIDEO: Qucs-S Simple Spice Simulation

Build an Op Amp SPICE Model from Its Datasheet – Part 1

Track My Order. Frequently Asked Questions. International Shipping Info. Send Email. Mon-Fri, 9am to 12pm and 1pm to 5pm U. Mountain Time:. If you haven't already been through the Getting Started with LTSpice guide, you should definitely wait as an update to the audio quality is desperately needed.

For those of you who watched it and finished it - bless you. I'd thought I'd kill two birds with one stone here and continue the LTSpice tutorial with an introduction to operational amplifiers -- or op amp for short. We will be covering just the basics here - what are op amps, some common configurations, and a couple examples - and we'll end with a nice, simple project to hopefully get you inspired to work with analog circuits a bit more.

An op amp is a voltage amplifying device. With the help of some external components, an op amp, which is an active circuit element, can perform mathematical operations such as addition, subtraction, multiplication, division, differentiation and integration.

If we look at a general op amp package innards to come in a later tutorial such as the ubiquitous , we'll notice a standard 8-pin DIP dual in-line package :. Photo courtesy of Learning About Electronics. We are mainly concerned with five of the pins. The circuit symbol for an op amp is a triangle with five pins shown below. An op amp has a wide range of uses and, depending how each pin is connected, the resulting circuit can be some of the following this is by no means a comprehensive list :. Throughout this tutorial I will show you how to measure typical op amp characteristics such as gain, bandwidth, error, slew-rate, current draw, output swing and other characteristics found on device data sheets.

The op amp is designed to detect the difference in voltage applied at the input the plus v2 and the minus v1 terminals, or pins 2 and 3 of the op amp package.

The difference is also known as the differential input voltage. The output, then, is the difference sensed at the input multiplied by some value A - the open-loop gain. An op amp behaves as a voltage-controlled voltage source, which we will model now. We will simulate both an open-loop and a closed-loop amplifier configuration. Since the output resistance Rout is zero, there is no voltage loss at the output. The diamond-shaped voltage source in the image above is known as voltage-dependent voltage source, and in this case the voltage is the gain G multiplied by the difference between the input terminals Vin.

The gain is normally referred to as A in texts, so the equation for the output is given by:. Let's model a voltage-controlled voltage source and see if we can't get its behavior to mimic an ideal op amp.

Op amps are not meant to be used as stand-alone devices. We simply verified the Vout equation in the ideal op amp video to show why it is commonly referred to as a voltage-controlled voltage source. We are going to talk about feedback and closed-loop gain and application. What is feedback? Feedback occurs when the output of a system is fed back into as input s. There are two types of feedback: positive regenerative and negative degenerative. Feedback is applied to the system to affect one or more of the following properties:.

When were talking about gain, we are taking the ratio of the output to the input. In the. Here's the conversion formula. All of the feedback comes at a price, and that cost is the gain. Negative feedback trades gain for more desirable properties; increasing the input resistance also increases the bandwidth. Unlike open-loop gain, the closed-loop gain is dependent on the external circuitry because of the feedback. However, it can be generalized. An example of an inverting configuration consists of one op amp and two resistors, R1 and R2.

R2 is connected from the output terminal of the op amp to the inverting or minus terminal of the op amp. R2 closes the loop around the op amp. One thing not mentioned in the video below, but is considered implied because we are still using the ideal op amp, is that no current flows through the op amp. All the current I1 flowing through R1 is also flowing through R2. This is known as the unity-gain inverter. A typical application for an inverting amplifier is a summing amplifier, also known as a virtual earth mixer, used in audio mixing.

I happen to have quite a few LM op amps lying around, so I went ahead and built a summing amplifier. First I modeled it in LTSpice. The voltage follower is a nice example of a non-inverting amplifier. The property of very high input impedance is a desirable feature of the non-inverting configuration.

The voltage follower can used as a unity-gain buffer amplifier connected from a high impedance source to a low impedance source - this helps to avoid loading effects on the driving circuit. Difference amplifiers respond to the difference between two signals applied at its input, and rejects signals that are common to the two inputs.

By combining these two topologies we are getting closer to be able to design a circuit that will be able to obtain the difference between the two input signals. In order to accomplish this, we must first make sure the gain magnitudes think absolute values that are always positive of each are equal.

We now have four resistors; we need to make sure the gains are equal so the ratio of the resistors is important:. The problem with this circuit is that in order to obtain high gain, R1 must be relatively low. This causes the input resistance to drop. Another issue is that it isn't easy to vary the gain of this amplifier. Both of these issues are solved with the implementation of the instrumentation amplifier.

Using three op amps, we can get a fine-tuned differential amplifier. Since we have the problem of low input resistance using one op amp, we can add an additional voltage follower or buffer at each input.

Even more awesome is that the buffers can add to the gain, easing the burden on the difference amplifier in the second stage. The instrumentation amplifier perfectly combines all the previous material: inverting and non-inverting amplifiers in cascade. We will not cover integrators, differentiators, oscillators or AD converters in this tutorial. Once we start adding capacitors and inductors, the math gets a bit more specialized and generalized in terms of impedance rather than resistance.

These will be a separate tutorial. If we look at a data sheet for the LM audio amplifier , we'll see a ton of parameters that help characterize the op amp. Most of these can be verified with simulation in LTSpice. Before we can get there let's define some of these characteristics. Common mode rejection ratio CMRR measures the amount of signal common to both inputs that is not amplified.

It is desirable for the common mode gain to be very low, which corresponds with a very high CMRR. The common mode rejection ratio is the ratio of the absolute value of differential gain to the absolute value of the common mode gain. The differential gain is typically half the intrinsic gain of the MOS transistor set by the manufacturer. Op amps with high output resistance will feature the best CMRR. The last thing you want in your design is to have that ripple amplified through your op amp.

The takeaway here is that to minimize the effects of ripple in power supplies, the Op Amp is required to have a large PSRR. So keep that in mind when looking at data sheets for any upcoming projects. Slew rate refers to the maximum rate of change possible at the output of an op amp. Most op amps are slew rate-limited, and that is calculated by taking the max of the derivative, with respect to time of the output voltage of the op amp.

The task of an audio amplifier is to take a small signal and amplify it without making any changes other than amplifying it. This is a difficult task because unwanted signals i. Any deviation from linearity is considered a distortion. Harmonic distortion is a common form of distortion in audio applications where the peaks of the output signal get "clipped.

Simulate, verify, build — my motto. In this case, the mini portable guitar amp project case, I took it too far. Below is a button where you can download the project files for what I am about to show you. I actually got this design to slightly out-perform the part I based my design off of, but it only works from 2 to 6 volts. Even though my LM model is not exactly like the part used in the project, it is still practical for looking at the electrical characteristics of op amps and getting more familiar with LTSpice.

I built a small, battery-powered amplifier into the case of my guitar using the LM and minimal extra parts. The circuit I took directly from the data sheet applications section Gain of :. The only changes I made were to the output capacitor. I didn't have a uF capacitor handy to I swapped it out for a uF. My guitar case has a little cubby for cables and picks so I used that space to build the amplifier into.

See it in action:. Ever wanted to get into DIY-synths but don't know where to start? If you are just getting into analog electronics projects, I cannot recommend Forrest Mims' Engineer's Mini Notebooks enough. EE Times has a fantastic article about common mode rejection ratio and differential amplifiers.

Spice Simulation Application Circuits

But have you ever wondered how the DJ controls the music and sound equipment at the night clubs? Then we must thank design engineers for inventing the differential amplifiers, which is the basic building block used in volume control circuits and automatic gain control circuits. Let us understand the working of a differential amplifier through circuit simulation using LTSpice tools. Differential amplifier is the fundamental building block in the CMOS analog integrated circuit design. The diff-amplifier amplifies the difference between the two input signal applied across the input terminal. The output of the differential amplifier is directly proportional to the difference between the two input signals. The difference between the input signals of the differential amplifier is known as the differential signals.

Simulators

Master the analysis and design of electronic systems with CircuitLab's free, interactive, online electronics textbook. Easy-wire mode lets you connect elements with fewer clicks and less frustration. Mixed-mode circuit simulation lets you simulate analog and digital components side-by-side. SPICE-like component models give you accurate results for nonlinear circuit effects. Human-friendly formats let you enter and display values concisely, just like you would on a paper schematic. Unit-aware expression evaluation lets you plot arbitrary signals of interest, such as differential signals or power dissipation. In-browser simulation and plotting lets you design and analyze faster, making sure your circuit works before ever picking up a soldering iron. Unique circuit URLs let you easily share your work or ask for help online. Bug-free design, excellent simulation.

POWER AMPLIFIERS & AND THEIR SIMULATIONS

Why do you need to build your own Op Amp model? Then why should you know how to build one? Well, not everything has a model and that is why, sometimes, you have to build your own. Also, it may be necessary to study a circuit to see what happens if you change the Op Amp slew rate or bandwidth, offset, and so on. Sometimes the manufacturer own model does not work, as a user found out and posted a question in this forum.

Subscribe to RSS

Spice is a program developed by the EE Department at the University of California at Berkeley for computer simulation of analog circuits. In its original form you tell Spice what elements are in the circuit resistors, capacitors, etc. Every node is assigned a number, and there is always a ground node, which is Number 0. Several companies have developed graphical user interfaces for Spice, which make it much easier to use. One of the most popular is PSpice. PSpice provides a free student version of its program which can be downloaded from www.

Types of SPICE simulation: Monte Carlo

Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. It only takes a minute to sign up. Connect and share knowledge within a single location that is structured and easy to search. I'm trying to simulate a simple common-emitter transistor amplifier presented as an example in Practical Electronics for Inventors in Qucs. The circuity is identical to the one presented in the book. To investigate the behavior of the amplifier, I feed a mV square wave at the input. It shows the voltage on the DC-blocking capacitor - it gets charged and starts output a stabilized AC signal, but unfortunately, it failed to show any voltage from the output side.

Spice Amplifier Tutorial using (.DC, .OP, .AC, .TRAN, .FOUR, .SUBCKT)

Included in the download of LTspice are macromodels for a majority of Analog Devices switching regulators, amplifiers, as well as a library of devices for general circuit simulation. Contact Technical Support for assistance. Our enhancements to SPICE have made simulating switching regulators extremely fast compared to normal SPICE simulators, allowing the user to view waveforms for most switching regulators in just a few minutes.

PartSim Circuit Simulator

RELATED VIDEO: Spice simulation of the Class A amplifier

One of the challenges of simulating op amp circuits is modeling the op amp itself. How is that accomplished? There's a couple of ways. You can create a circuit of many transistors, resistors and caps that closely replicate the internals of an op amp. Or, you can create a simpler model that reproduces the basic behavior of the op amp. The benefit of the simpler model is one that uses less components and typically simulates faster.

Power Amplifiers

Note the following requirements:. The motivation for developing LiveSPICE is to help prototype guitar effects and amplifiers, without requiring constructing a physical circuit or waiting for an offline simulation to run to try it out. With LiveSPICE, you can design the circuit in an easy to use visual schematic editor, and simulate it using your real audio device as an input signal and your speakers as the output. Transient simulation of circuits is an extremely computationally intensive task, making it difficult to perform in real time. In addition, circuit simulation is a difficult problem to parallelize, meaning that most of the computer power improvements in recent years are not useful to speed up circuit simulation. In order to deliver real time, low latency transient simulations for audio signals, LiveSPICE is somewhat unique among circuit simulators in the following ways:.

PCB Design & Analysis

Skip to Main Content. A not-for-profit organization, IEEE is the world's largest technical professional organization dedicated to advancing technology for the benefit of humanity. Use of this web site signifies your agreement to the terms and conditions. SPICE applications to an undergraduate electronics program Abstract: A plan is presented for integrating SPICE simulation program with integrated circuit emphasis into an undergraduate electronics curriculum.