Name: ecg signal amplifier design
Uploaded: 2025-07-11T07:24:08.000Z
Duration: 1 min 25 s
Channel: JoVE

Em uma máquina de eletrocardiografia, os eletrodos detectam pequenas alterações elétricas na pele resultantes da despolarização do músculo cardíaco durante cada batimento cardíaco.
Esses sinais de faixa de microvolts podem ser sobrecarregados por ruído ou interferência.
Para corrigir isso, a máquina de ECG usa um amplificador de instrumentação para amplificar a forma de onda do ECG, minimizando os sinais de ruído de modo comum.
O amplificador de instrumentação é um tipo de amplificador de diferença. Inclui seis resistores, três terminais e um resistor externo conectado entre os terminais do conjunto de ganho.
Ele amplifica pequenas diferenças entre os sinais de entrada enquanto rejeita sinais comuns a ambas as entradas.
A tensão de saída é o produto do ganho de tensão e da diferença de tensão de entrada., O ganho pode ser facilmente ajustado variando apenas o resistor externo.
Os amplificadores de instrumentação têm alta impedância de entrada, baixa impedância de saída, alta estabilidade de ganho e uma alta taxa de rejeição de modo comum.
A alta impedância de entrada evita a distorção do sinal, evitando a carga do sinal, e o alto CMRR ajuda a rejeitar ruídos captados pelos cabos do eletrodo, como interferência elétrica de outros equipamentos.
Os amplificadores de instrumentação são usados em instrumentação biomédica e telecomunicações.

amplificador de instrumentação

Uma máquina de eletrocardiografia (ECG) é um equipamento médico essencial usado para monitorar a atividade elétrica do coração. Ele opera detectando pequenas alterações elétricas na pele que resultam da despolarização do músculo cardíaco durante cada batimento cardíaco. No entanto, estes sinais estão na faixa de microvolts e podem ser facilmente sobrecarregados por ruído ou interferência.

Para superar esse desafio, uma máquina de ECG utiliza um amplificador de instrumentação. Este amplificador especializado foi projetado para amplificar a forma de onda do ECG e, ao mesmo tempo, minimizar o impacto dos sinais de ruído de modo comum, como interferência elétrica de outros dispositivos.

O amplificador de instrumentação é um tipo de amplificador diferencial. Seu circuito inclui seis resistores, três terminais e um resistor externo conectado entre os terminais do conjunto de ganho. Esse amplificador funciona amplificando as pequenas diferenças entre os sinais de entrada enquanto rejeita os sinais comuns a ambas os inputs.

A tensão de saída do amplificador é determinada pelo produto do ganho de tensão pela diferença de tensão de entrada. O ganho pode ser facilmente ajustado variando o valor do resistor externo, proporcionando flexibilidade e controle sobre o processo de amplificação.

Os amplificadores de instrumentação apresentam diversas características importantes que os tornam ideais para uso em máquinas de ECG. Eles têm alta impedância de entrada, baixa impedância de saída, alta estabilidade de ganho e alta taxa de rejeição de modo comum (CMRR).

A alta impedância de entrada evita a distorção do sinal, evitando a carga do sinal, garantindo a integridade dos sinais elétricos do coração. O alto CMRR permite que o amplificador rejeite efetivamente ruídos captados pelos eletrodos, como interferência elétrica de outros equipamentos, melhorando assim a qualidade da forma de onda do ECG.

Além de seu uso em máquinas de ECG, os amplificadores de instrumentação são comumente empregados em uma variedade de aplicações de instrumentação biomédica e telecomunicações devido às suas propriedades únicas.

Amplificador de Instrumentação

Em uma máquina de eletrocardiografia, os eletrodos detectam pequenas alterações elétricas na pele resultantes da despolarização do músculo cardíaco durante cada ...

Education

JoVE Core

Electrical Engineering

Engenharia Elétrica

Unit 1

Unidade 1

Operational Amplifiers

Amplificadores Operacionais

KEY TERMS AND CONCEPTS

TERMOS-CHAVE E CONCEITOS

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 appears on both inputs. It works as a difference amplifier, so it strengthens the small voltage difference between the two input signals and rejects the signals they share.

The circuit uses six resistors, three terminals, and an external resistor connected between the gain set terminals. The output voltage depends on the voltage gain and the input voltage difference. The gain can be adjusted by changing the value of the external resistor, which gives the circuit flexibility.

Instrumentation amplifiers are well suited for ECG systems because they have high input impedance, low output impedance, high gain stability, and a high common mode rejection ratio, or CMRR. High input impedance helps prevent signal loading, so the heart signal is not distorted. High CMRR helps block interference picked up by the electrode leads, such as noise from other equipment, and improves the ECG waveform. These amplifiers are also used in other biomedical instrumentation and telecommunication applications.

ECG Signal Amplifier Design

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

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,...

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

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 an instrumentation amplifier helps an ECG machine boost tiny heart signals, reject noise, and improve waveform quality using adjustable gain and high CMRR.

ECG Signal Amplifier Design | 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

ECG Signal Amplifier Design

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