A linear circuit is designed in such a manner that any electronic accessory or component remains consistent. It also ensures that all the different properties of the circuit, including impedance, resistance, gain, and capacitance, undergo no alteration throughout the circuit. This is regardless of any possible voltage changes that may occur between components throughout the circuit.
In electrical circuitry, the term linear represents the formatting of the circuit being used. In order for a circuit to be considered a linear circuit, it must not contain any form of nonlinear component. This means that there may not be a diode or a transistor element within the circuit, nor any iron-core conductors.
In the electronic manufacturing industry, linear circuits are given their own designation within the manufacturing process. Circuit board manufacturers as well as electronic device manufacturers must maintain the separation between linear and nonlinear products. This usually means they separate their linear products from their digital product manufacturing lines to maintain the integrity of the linear-based products. For instance, the manufacturing of an amplifier circuit that behaves linearly is not manufactured on the same line as an op-amp that contains transistors of any kind because transistors behave in a nonlinear fashion, which would take away from the linear amplifier’s base function.
Linear circuitry is also used in electronic device protection methods. Some surge protector units, as well as industrial and residential circuit breakers, utilize linear circuitry as a means of safely dissipating the amount of power introduced to another circuit. These are used because a linear circuit is able to dissipate the power more evenly as it passes through the circuit than that of a nonlinear circuit.
A nonlinear circuit contains nonlinear components, which fall subject to shorting or failure that can result in the malfunction of the circuit-protecting device. If a resistor or diode unit within a nonlinear circuit in a surge protector fails, the device allows the increased voltage from a power surge to pass directly through it without providing any resistance of power. Linear circuits aren't subject to these issues.
In order to be considered a linear circuit, it must possess a superposition property. This means that, regardless of the number of inputs the circuit has, the output of the circuit in terms of voltage or signal is the same as the actual sum of each one of the inputs being added together. No change in the inputs occurs through the signal being passed through a linear circuit.