Amplificadores operacionales

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MATERIAL

• 1 tablet PROTOBOARD experimentation.
• 3 coaxial cables with BNC-Cayman terminal.
• 4 Wire CAYMAN - Cayman.
• 3 Wire BANANA - Cayman.
• 2 LM741 (Operational Amplifier)
• 6 resistors 1k ¼ W.
• 3 10k Resistors 1 / 4W
• 5 100k resistors ¼ W.
• 1 560KΩ resistor ¼ W
• 1 Resistor 560Ω 1 ¼ W.
• 2 15KΩ resistors ¼ W
• 1 150KΩ resistor ¼ W
• 2 2.2KΩ resistors ¼ W
• 1 Resistor 3.3 KQ ¼ W
• 1 Resistor 2.2 KQ ¼ W
• 1 Resistor KQ 220 ¼ W
• 1 Resistor 4.7 Ohm at ¼ W
• 1 KQ resistor 15 ¼ W
• 1 KQ resistor 82 ¼ W
• 1 Capacitor 0.01 μ F
• 1 μ F capacitor 0.0022
• 1 100 pF capacitor

EQUIPMENT

• 1 power supply and dual + 12V - 12V
• 1 digital or analog multimeter.
• One Function Generator 10Hz-1MHz.
• 1 general purpose oscilloscope.

Objectives:

• Check analog circuits

• Inverting amplifier.
• Non-inverting amplifier.
• Voltage follower.
• Summing amplifier.
• Subtractor amplifier
• Integrator amplifier
• amplifier Shunt

• Interpret the results obtained for the above circuits.
• In all the operational amplifier circuits 741 to ± 12V supply is used.

INTRODUCTION

An operational amplifier (op-amp) is a DC-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output. In this configuration, an op-amp produces an output potential (relative to circuit ground) that is typically hundreds of thousands of times larger than the potential difference between its input terminals.

Operational amplifiers had their origins in analog computers, where they were used to do mathematical operations in many linear, non-linear and frequency-dependent circuits. Characteristics of a circuit using an op-amp are set by external components with little dependence on temperature changes or manufacturing variations in the op-amp itself, which makes op-amps popular building blocks for circuit design.

Op-amps are among the most widely used electronic devices today, being used in a vast array of consumer, industrial, and scientific devices. Many standard IC op-amps cost only a few cents in moderate production volume; however some integrated or hybrid operational amplifiers with special performance specifications may cost over $100 US in small quantities. Op-amps may be packaged as components, or used as elements of more complex integrated circuits.

The op-amp is one type of differential amplifier. Other types of differential amplifier include the fully differential amplifier (similar to the op-amp, but with two outputs), the instrumentation amplifier (usually built from three op-amps), the isolation amplifier (similar to the instrumentation amplifier, but with tolerance to common-mode voltages that would destroy an ordinary op-amp), and negative feedback amplifier (usually built from one or more op-amps and a resistive feedback network).

AMP INVESTOR

This show is so named because the output signal is input inverse in polarity, but could be higher, the same or lower, depending on the gain that we give to the amplifier in closed loop. The signal as shown in the figure, is applied to the inverter or negative terminal of the amplifier and the positive or non-inverting takes mass. Resistor R2, which runs from the outlet to the negative input terminal is called feedback.

VOLTAGE FOLLOWER

The voltage follower with an ideal op amp, gives just Vout = Vin

But this result is a very useful application , because the input impedance of the op amp is very high , providing an insulating effect with respect to the output of the input signal , negating the effects of "burden" . This makes it a useful first stage circuit.

The voltage follower is often used in logic circuits, to build buffers.

SUMMING AMPLIFIER INVESTOR

The adder is a useful circuit, based on the standard configuration of the inverting operational amplifier. This circuit combines multiple inputs, ie, can add algebraically two (or more) signals or voltages to form the sum of these signals.

The reason to use an operational amplifier to add multiple input signals, is to prevent the interaction between them, so that any change in the voltage of the entries will not affect other inputs.

SUBTRACTING AMPLIFIER

Some applications require that the "difference" between two voltages is amplified. This is the case of a control system in which the comparator tom to the difference between the input voltage and the feedback voltage. Another example is found in biomedical applications, in which a measurement of the voltage difference between two points of the patient's body is performed. In these cases the differential op-amp configuration shown in Figure (5) is required. If it is grounded V1, V2 then contemplates an inverting configuration. If V1 is grounded (through a voltage divider), you will see a non-inverting configuration.

INTEGRATING AMPLIFIER

The integrating circuit is a circuit with an operational amplifier that performs the mathematical operation of integration. The circuit acts as a storage element which produces a voltage output that is proportional to the time integral of the input voltage.

If an input signal constantly changing the input of an integrator amplifier is applied, for example a square wave, the capacitor is charged and discharged in response to changes in the input signal. Thus, an output signal in sawtooth shape, whose frequency depends on the RC time constant of the combination of resistor and capacitor is created.

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