Basic Principles of Op-Amp (Operational Amplifier)

By | August 13, 2021

Definition of Op-Amp (Operational Amplifier)

Operational Amplifier (Op-Amp) is a form of linear IC that functions as an electrical signal amplifier. An Op-Amp consists of several Transistors, Diodes, Resistors and Capacitors which are interconnected and integrated so as to enable it to produce high Gain (gain) over a wide frequency range. In Indonesian, the Op-Amp or Operational Amplifier is often referred to as an Operational Amplifier.
Op-Amps are generally packaged in IC form, an Op-Amp IC can consist of only 1 (one) Op-Amp circuit or it can also consist of several Op-Amp circuits. The number of Op-Amp circuits in one IC package can be divided into Single Op-Amp, Dual Op-Amp and Quad Op-Amp. There is also an IC in which there is an Op-Amp circuit in addition to the other main circuit.
An Op-Amp circuit has two inputs, namely one Inverting Input and one Non-inverting Input and has one Output (output). An Op-Amp also has two power supply connections, one for positive power supply and one for negative power supply. The shape of the Op-Amp symbol is a triangle with input, output and power supply lines as shown below. One of the most popular types of Op-Amp ICs is the IC741.

Forms and Symbols of Op-Amp IC

The following are the symbols and forms of the Op-Amp IC in general.

Op-amp Symbol

Op-amp IC pin configuration

Op-amp IC Form


The terminals contained in the Op-Amp Symbol (Operational Amplifier / operational amplifier) ​​include:
1. Input non-inverting (Non-Inverting) +
2. Inverting input –
3. Output Vout
4. Positive power supply +V
5. Negative power supply -V

Op-Amp (Operational Amplifier) ​​Characteristics

The characteristics of the amplifier or gain factor in the op-amp are generally determined by the external resistor connected between the output and the inverting input. Configuration with negative feedback (Negative Feedback) is usually called a Closed-Loop configuration or closed-loop configuration. This negative feedback will cause the gain or gain to be reduced and produce gain that can be measured and can be controlled. The purpose of reducing the gain of this op-amp is to avoid excessive noise and also to avoid unwanted responses. While in the Open-Loop Configuration, the gain is infinity (∞) so that the output voltage is almost or close to Vcc.

In general, the ideal Operational Amplifier (Op-Amp) has the following characteristics:
 Open-loop Voltage Gain or Av = (infinity)
 Output Offset Voltage or Voo = 0 (zero)
 Input Impedance (Input Impedance) or Zin = (infinity)
 Output Impedance (Output Impedance ) or Zout = 0 (zero)
 Bandwidth or BW = (infinity)
 Characteristics do not change with temperature

Basically, the ideal op-amp conditions are only theoretical and almost impossible to achieve in practical conditions. But Op-Amp device manufacturers always try to produce Op-Amp that is close to this ideal condition. Therefore, a good Op-Amp is an Op-Amp that has characteristics that are close to the conditions of an Ideal Op-Amp.