Name: op-amp gain, feedback, and saturation
Uploaded: 2025-05-22T09:06:14.000Z
Duration: 1 min 17 s
Channel: JoVE

Considere el modelo de circuito equivalente de un amplificador operacional. La sección de salida consta de una fuente controlada por voltaje en serie con la resistencia de salida.
En la sección de entrada, v1 y v2 denotan voltajes desde los terminales inversores y no inversores a tierra, respectivamente.
El voltaje de salida de un amplificador operacional es igual al producto de la diferencia de voltaje de entrada y la ganancia de bucle abierto.
Para pequeñas diferencias de voltaje, el amplificador operacional se comporta linealmente. Si el voltaje excede el voltaje de la fuente de alimentación, el amplificador operacional se satura.
La combinación de voltaje aplicado y retroalimentación negativa garantiza que el amplificador operacional funcione dentro de su rango lineal.
Los amplificadores modernos tienen grandes ganancias y resistencia de entrada, lo que les permite aproximarse como amplificadores operacionales ideales.
Un amplificador operacional ideal tiene una ganancia de bucle abierto infinita, una resistencia de entrada infinita y una resistencia de salida cero. Tanto las corrientes de los terminales de entrada como el voltaje de compensación de entrada son cero en un amplificador operacional ideal.
Además, tiene un ancho de banda infinito, lo que le permite amplificar señales de cualquier frecuencia, y una velocidad de respuesta infinita, lo que significa su capacidad para cambiar el voltaje de salida rápidamente con el tiempo.

características del amplificador operacional

El amplificador operacional, comúnmente conocido como amplificador operacional, es un componente de circuito electrónico especialmente diseñado. Su propósito es trabajar en conjunto con otros elementos del circuito para ejecutar una operación de procesamiento de señal definida. Considere un modelo de circuito equivalente de un amplificador operacional, como se muestra en la Figura 1; la sección de salida comprende una fuente controlada por voltaje en paralelo con la resistencia de salida Ro. <img alt="Figure1" src="/files/ftp_upload/15077/15077_PT_Figure_1.svg" style="text-align: center; height: 166px;"> Figure 1: El circuito equivalente del amplificador operacional no ideal La Figura 1 muestra que la resistencia de entrada Ri equivale a la resistencia equivalente de Thėvenin observable en los terminales de entrada. De manera similar, la resistencia de salida Ro corresponde a la resistencia equivalente de Thėvenin discernible en la salida. El voltaje de entrada diferencial (vd) se calcula como la diferencia entre el voltaje del terminal no inversor con respecto a tierra y el voltaje del terminal inversor con respecto a tierra. El amplificador operacional discierne la diferencia entre estas dos entradas y la amplifica mediante la ganancia A, generando así un voltaje que aparece en la salida. Aquí, A representa la ganancia de voltaje de bucle abierto, denominada así porque significa la ganancia del amplificador operacional en ausencia de retroalimentación externa desde la salida a la entrada. La retroalimentación es un concepto integral que debe comprenderse al estudiar circuitos de amplificadores operacionales. La retroalimentación negativa se puede lograr devolviendo la salida al terminal inversor del amplificador operacional. Cuando existe una ruta de retroalimentación de salida a entrada, la relación resultante entre el voltaje de salida y el voltaje de entrada se conoce como ganancia de circuito cerrado. El amplificador operacional tiene sus limitaciones prácticas. Una de esas limitaciones es que la magnitud de su voltaje de salida no puede superar |VCC|. Básicamente, el voltaje de la fuente de alimentación determina y restringe el voltaje de salida. Dependiendo del voltaje de entrada diferencial, el amplificador operacional puede funcionar en uno de tres modos: saturación positiva, región lineal o saturación negativa. Si se intenta aumentar vd más allá del rango lineal, el amplificador operacional alcanza la saturación, produciendo vo = VCC o vo = -VCC.

Características del amplificador operacional

Considere el modelo de circuito equivalente de un amplificador operacional. La sección de salida consta de una fuente controlada por voltaje en serie con la salida ...

Education

Educación

JoVE Core

Electrical Engineering

Ingeniería Eléctrica

Unit 1

Unidad 1

Operational Amplifiers

Amplificadores Operacionales

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

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 the noninverting terminal voltage and the inverting terminal voltage, both measured relative to ground. The op-amp compares these two input voltages and amplifies the difference by the gain A to produce an output voltage.

A is called the open-loop voltage gain because it describes the op-amp without feedback from the output back to the input. Feedback is important in op-amp circuits. Negative feedback is created by connecting the output to the inverting terminal. When that feedback path exists, the output-to-input ratio is the closed-loop gain.

Op-amps also have practical limits. Their output voltage cannot exceed the magnitude of the supply voltage, |VCC|. The power supply sets this limit. Depending on the differential input voltage, the op-amp can operate in positive saturation, the linear region, or negative saturation. If v d is pushed beyond the linear range, the output saturates at either v o = VCC or v o = -VCC.

Op-Amp Gain, Feedback, and Saturation

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

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

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 an op-amp compares input voltages, uses open-loop and closed-loop gain, and reaches positive or negative saturation when output limits are exceeded.

Op-Amp Gain, Feedback, and Saturation | 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 Gain, Feedback, and Saturation

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