Name: op-amp adders and subtractors
Uploaded: 2024-04-11T12:48:35.000Z
Duration: 1 min 22 s
Channel: JoVE

Um amplificador de somação, ou um somador, usa um amplificador operacional para combinar vários sinais de entrada em uma única saída.
Por outro lado, um amplificador de diferença, ou um subtrator, amplifica a diferença entre dois sinais de entrada.
Considere um circuito de mixagem de áudio com um amplificador operacional.
Quando os sinais de áudio são alimentados nos canais de entrada, os resistores de entrada geram correntes que fluem através dos resistores de realimentação, produzindo uma tensão de saída.
Usando a lei de corrente de Kirchhoff no nó de entrada do amplificador operacional em conjunto com a Lei de Ohm, a tensão de saída resultante é proporcional à soma ponderada dos sinais de entrada.
Um circuito básico de amplificador operacional diferencial pode reduzir parcialmente o ruído da faixa de áudio nesta mixagem.
A aplicação de KCL nos nós inversores e não inversores produz duas equações. Com tensões iguais em ambos os nós, uma expressão de tensão de saída é obtida.
O amplificador de diferença pode anular sinais comuns a ambas as entradas somente quando as taxas de resistência atendem a certas condições. Como resultado, uma saída diferencial é obtida.
Quando a resistência R2 é igual a R1 e R3 é igual a R4, o amplificador de diferença funciona como um subtrator.

amplificadores operacionais de soma e diferença

Amplificadores operacionais (do inglês op-amps) são dispositivos versáteis que vão além da amplificação. Neste contexto, duas configurações específicas de op-amps são exploradas: os amplificadores somadores e os amplicadores subtratores.

Um amplificador somador, também conhecido como somador, utiliza um amplificador operacional para mesclar vários sinais de entrada em um único sinal de saída. Quando sinais de áudio são introduzidos em seus canais de entrada, os resistores de entrada iniciam correntes que atravessam os resistores de feedback, resultando em uma tensão de saída. Aplicando a lei das correntes de Kirchhoff e a lei de Ohm, a tensão de saída torna-se uma soma ponderada dos sinais de entrada. Esse circuito básico de op-amp diferencial desempenha um papel na mitigação de ruídos de faixas de áudio em aplicações de mixagem de áudio.

<img alt="Equation1" src="/files/ftp_upload/15079/15079_PT_Equation_1.svg" style="text-align: center; height: 32px;" />

Por outro lado, um amplificador diferencial, geralmente chamado de subtrator, amplifica a disparidade entre dois sinais de entrada. Duas equações são estabelecidas aplicando a lei das correntes de Kirchhoff nos nós inversores e não inversores. Uma expressão de tensão de saída é derivada quando existem tensões iguais em ambos os nós. No entanto, condições específicas de relação de resistência devem ser satisfeitas para que o amplificador diferencial anule os sinais comuns entre as entradas. Quando as resistências nos ramos correspondentes são iguais, o amplificador diferencial funciona como um subtrator.

<img alt="Equation2" src="/files/ftp_upload/15079/15079_PT_Equation_2.svg" style="text-align: center; height: 32px;" />

Em resumo, os amplificadores operacionais oferecem amplificação e a capacidade de realizar tarefas de adição e subtração. O amplificador somador combina entradas em uma soma ponderada. O amplificador subtrator amplifica a diferença entre duas entradas e rejeita sinais comuns. A compreensão dessas configurações abre caminho para muitas aplicações práticas em processamento de sinais e design de circuitos.

Amplificadores operacionais de soma e diferença

Um amplificador de somação, ou um somador, usa um amplificador operacional para combinar vários sinais de entrada em uma única saída.
Por outro lado, uma diferença ...

Education

JoVE Core

Electrical Engineering

Engenharia Elétrica

Unit 1

Unidade 1

Operational Amplifiers

Amplificadores Operacionais

KEY TERMS AND CONCEPTS

TERMOS-CHAVE E CONCEITOS

Sum and Difference OpAmps

op-amp adders and subtractors

Operational amplifiers can be wired to add or subtract signals. In these two op-amp setups, the summing amplifier combines several input signals into one output, while the difference amplifier compares two inputs and amplifies their difference.

A summing amplifier is also called an adder. Input signals, such as audio signals, enter through input resistors. These resistors send currents through the feedback resistor, which produces an output voltage. Using Kirchhoff's current law and Ohm's Law, the output becomes a weighted sum of the inputs. This type of circuit can help reduce noise in audio mixer applications.

A difference amplifier is also called a subtractor. It amplifies the difference between two input signals. To describe its behavior, two equations are written by applying Kirchhoff's current law at the inverting and non-inverting nodes. When equal voltages appear across both nodes, an output voltage expression can be derived. Specific resistance ratios must be met for the circuit to cancel signals that are common to both inputs. When the resistances in the matching branches are equal, the difference amplifier works as a subtractor.

These op-amp circuits show that operational amplifiers do more than boost signals. They can perform addition and subtraction in circuit design. The summing amplifier creates a weighted total of multiple inputs, and the difference amplifier rejects common signals while highlighting the difference between two inputs. These ideas are useful in signal processing and many practical electronics applications.

Op-Amp Adders and Subtractors

operational amplifiers

Operational Amplifier Pinout and Signal Use

An operational amplifier, or op-amp, is a flexible circuit building block used in many electronic designs. It can act like a voltage-controlled voltage source, and it can also be used to create a voltage- or current-controlled current source. When resistors and capacitors are connected to its terminals, an op-amp can perform mathematical operations on signals. Op-amps are able to sum signals, amplify a signal, integrate it, or differentiate it. These features make them useful in practical...

design example: vintage mixing console

Op-Amp Preamp for a Vintage Console

A sound engineer designs an op-amp pre-amplifier for a vintage mixing console. The console’s output is too low for modern recording equipment, so the signal must be boosted before it can be used. The goal is to build a preamp that raises the audio level without changing the console’s character. The design must meet three clear requirements. It needs a gain of 10, an input impedance above 10 kilo-ohms so the console is not overloaded, and a frequency range that covers the full audio spectrum...

characteristics of opamp

Op-Amp Gain, Feedback, and Saturation

An operational amplifier, or op-amp, is an electronic circuit component used with other circuit parts to carry out a signal-processing task. It is often described with an equivalent circuit model. In that model, the output section includes a voltage-controlled source in parallel with the output resistance, R o. The model also shows the input resistance, R i, which is the Thevenin equivalent resistance seen at the input terminals. The differential input voltage, v d, is the difference between...

inverting and non-inverting opamps

Op-Amp Gain: Inverting, Noninverting, Buffer

Operational amplifiers can be used as inverting, noninverting, and buffer amplifiers. In these circuits, the output voltage depends on the input voltage and the resistor setup around the op-amp. In an inverting amplifier, the input voltage is sent through a resistor to the inverting terminal. The non-inverting terminal is grounded, and a feedback resistor links the inverting terminal to the output. Using Kirchhoff's Current Law and an ideal op-amp model, the gain can be found. This circuit...

sum and difference opamps

Operational amplifiers can be wired to add or subtract signals. In these two op-amp setups, the summing amplifier combines several input signals into one output, while the difference amplifier compares two inputs and amplifies their difference. A summing amplifier is also called an adder. Input signals, such as audio signals, enter through input resistors. These resistors send currents through the feedback resistor, which produces an output voltage. Using Kirchhoff's current law and Ohm's Law,...

characteristics of practical op amps

Op Amp Noise Rejection and Buffering

Practical op amps are used to separate useful signals from unwanted noise. A difference amplifier should ideally amplify only the difference between two input signals. In real circuits, though, the output depends on both differential gain and common-mode gain. The common-mode rejection ratio, or CMRR, measures how well an op amp rejects common-mode signals. Common-mode signals are the same on both inputs. A higher CMRR helps an op amp ignore noise and amplify the wanted signal, such as music...

integrator and differentiator

Op-Amp Circuits in Cruise Control

Op-amp circuits are used in cruise control systems to help cars keep a constant speed. In these systems, operational amplifiers, or op-amps, can work as integrators and differentiators. Both circuits use resistors and capacitors, which makes them compact and cost-effective. An integrator circuit produces an output that is proportional to the integral of the input signal. It is made by replacing the feedback resistor in a standard inverting amplifier with a capacitor. The output and input...

cascaded op amps

Op Amp Stages in Series

Operational amplifiers can be connected in series as separate stages. This cascade works because op-amps have very high input resistance and very low output resistance. Those properties help each stage keep its input-output relationship while driving the next stage. In a cascaded op-amp circuit, the output of one stage becomes the input of the next. Each stage adds gain to the signal as it passes through. The overall gain is the product of the gain of each stage. This design can improve...

instrumentation amplifier

ECG Signal Amplifier Design

An ECG signal amplifier helps an electrocardiography machine measure the heart’s electrical activity. ECG electrodes detect tiny voltage changes on the skin that come from depolarization of the heart muscle during each heartbeat. These signals are in the microvolt range, so they can be easily hidden by noise or interference. To solve this problem, ECG machines use an instrumentation amplifier. This amplifier boosts the ECG waveform while reducing common-mode noise, which is interference that...

key terms and concepts

Learn how op-amp adders and subtractors combine signals, compare two inputs, and use resistor ratios to create weighted sums and signal rejection.

Op-Amp Adders and Subtractors | JoVE K12

JoVE Core Electrical Engineering offers easy-to-understand animated videos that cover fundamental concepts of electric circuits along with circuit analysis techniques. It incorporates first-order and second-order circuits using operational amplifiers and circuit transformation concepts. The inclusion of practical design examples and real-world applications through scientist-in-action videos adds significant educational value, making complex concepts accessible.

electrical engineering

Op-Amp Adders and Subtractors

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