A gyrator circuit is an electronic circuit element that simulates the behavior of an ideal inductor or a magnetic coil. It is named after the term "gyration," which refers to the hypothetical rotation of electrical charge. While a gyrator itself is not a physical inductor, it can effectively behave like one in certain applications.
The primary function of an inductor is to store energy in the form of a magnetic field when current flows through it. However, in some cases, using physical inductors can be impractical due to their size, weight, and cost. Gyrator circuits offer an alternative solution to implement inductance-like properties without the need for an actual inductor.
A typical gyrator circuit consists of active components such as operational amplifiers (op-amps) and passive components like resistors and capacitors. By cleverly arranging these components, the circuit can imitate the behavior of an inductor.
The main properties of an ideal gyrator are as follows:
Impedance inversion: A gyrator circuit reverses the impedance seen at its input and output terminals. For instance, if you apply a voltage signal across the input terminals, the current flowing out of the output terminals will have an impedance proportional to the reciprocal of the input impedance. This behavior is analogous to how an inductor responds to changes in current and voltage.
Energy transfer: A gyrator circuit can transfer energy from one part of the circuit to another, much like an inductor transferring energy between its magnetic field and the connected circuit.
Gyrator circuits find various applications in electronics, especially in filter design. They are commonly used to realize inductance in active filter circuits where physical inductors would be impractical. Gyrators also appear in analog computing, signal processing, and certain types of oscillators.
It's important to note that gyrators have some limitations and may not perfectly replicate all characteristics of physical inductors. For example, they are subject to certain frequency limitations and can't be used in all situations where inductors are needed. Nevertheless, in many applications, gyrator circuits provide a useful and space-saving alternative to using traditional inductors.