3.1: Operational Amplifiers
The operational amplifier, often referred to as an op-amp, is a multifaceted building block of a circuit. This electronic component functions like a voltage-controlled voltage source and can also be used to create a voltage- or current-controlled current source. The design of an operational amplifier enables it to execute mathematical operations when external components like resistors and capacitors are linked to its terminals. An op-amp has the capacity to sum signals, amplify a signal, integrate it, or differentiate it.
The op-amps are popular in practical circuit designs due to their adaptability, affordability, and ease of use. An op-amp consists of a complex network of resistors, transistors, capacitors, and diodes. Op-amps are commercially available in different forms of integrated circuit packages. One common type is the eight-pin dual in-line package (DIP), as depicted in Figure 1.
Figure 1: A typical op amp pin configuration
Pin 8 is not used, and pins 1 and 5 are of minor concern. The five significant terminals are the inverting input (pin 2), the noninverting input (pin 3), the output (pin 6), the positive power supply V (pin 7), and the negative power supply V (pin 4). The circuit symbol for the op-amp is a triangle, as shown in Figure 2.
Figure 2: A typical op-amp circuit symbol
The op-amp has two inputs and one output, with the inputs marked with a minus (-) and a plus (+) to denote inverting and noninverting inputs, respectively.
An input applied to the noninverting terminal will appear with the same polarity as the output, while input applied to the inverting terminal will appear inverted as the output. As an active component, the op-amp necessitates a voltage supply for power. The current drawn from power supplies is a combination of the output current and the current needed to power the amplifier's internal circuitry.
