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Operational Amplifier | OP-AMP Basic


An operational amplifier (OP-AMP) is a very stable amplifier that can be used for a large number of linear and non-linear operations by using some external elements, i.e., resistors, capacitors, diodes, etc. It is made in the form of a little chip called an integrated circuit. It is also called OP-AMP because it was originally designed to perform mathematical operations like addition, multiplication, subtraction, differentiation, integration, etc. on analog computers. The OP-AMP provides voltage changes, oscillations, filtration, etc. in many types of electronics and communication circuits.

Basic Operational Amplifier

The operational amplifier (OP-AMP) is a very high gain, differential (two inputs of opposite polarity) amplifier with a high input impedance and a low output impedance.

The common integrated circuit operational amplifier is made up of several transistor stages on a signal chip and functions as a voltage-controlled voltage source.

Operational Amplifier

The OP-AMP has two inputs (i.e. inverting input and non-inverting input) and one output. The two OP-AMP inputs are connected to Pin 2 (-ve sign) and Pin 3 (+ve sign) while inverting the OP-AMP output is connected to Pin 6. The terminal at 2 with the -ve Non-Inverting sign is called inverting input terminal whereas Input the terminal at 3 with a +ve sign is called non-inverting input terminal. Pin 7 connects to the positive terminal of the power supply (+Vcc) and Pin 4 connects to the negative terminal of the power supply (-Vec).

The OP-AMP input can be single-ended or double-ended (or differential input), depending on whether the input voltage is applied to one or both input terminals. Similarly, amplifier output can also be either single-ended or double-ended. But the most common configuration is two input terminals and a single output. Some common operation of OP-AMP is explained below.

(1) Single Ended Operation of OP-AMP

When an input signal is connected to one input terminal (non-inverting input) and the second input terminal is connected to the ground (inverting input), this configuration is known as a single-ended operation and produces an output with the same polarity as the applied input signal. The result is reversed if the input signal is applied to the minus input. As a result, the output phase is opposite the phase of the applied signal.

Single Ended Operation of OP-AMP

(2) Double Ended Operation of OP-AMP

If the signal is applied to both the inputs (positive and negative). The amplified output is then in phase with the applied signals at both inputs. Similarly, if two separate signals are applied then the resulting output signals are the difference between the two inputs. This type of configuration is known as a double-ended operation.

Double Ended Operation of OP-AMP

The input is applied between the two input terminals, and the output is taken between the two output terminals. This is a completely differential operation.

Frequently Asked Questions (FAQs)

  1. What is an operational amplifier?

    An operational amplifier, or op-amp for short, is an electronic device that can amplify weak electric signals. An OP-AMP has two input pins and one output pin. Its basic role is to amplify and output the voltage difference between the two input pins.

  2. What is input offset voltage?

    Input offset voltage

    When the two input voltages (i.e. V₁, V₂) of an OP-amp are made equal, then the output of ideal OP-amp is zero (i.e. Vout = 0).

  3. What is input bias current?

    A small value of dc current that flows into the input terminal of transistor to bias the input of transistor, is known as input bias current.

  4. Define the term slew rate?

    slew rate

    The slew rate is the maximum rate at which amplifier output can change in volt/S or volt/μS. It is represented by SR.

  5. What do you mean by OP-AMP as an integrator?

    When the output of OP-AMP is proportional to the integral of the input voltage, then such an amplifier is known as the OP-AMP integrator.

  6. What do you mean by OP-AMP as a differentiator?

    When the output of OP-AMP is proportional to the rate of change of input voltage, then such an amplifier is called a differentiator OP-AMP.

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Er. Hansraj Banger

Hansraj Banger is an electrical engineer with a wide range of skills that include web development, web design, content writing, and blogging. He seems to be a passionate educator who enjoys learning new things and sharing his knowledge with others.

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