 An equivalent definition is that a linear circuit is a circuit in which, when a sinusoidal input voltage or current of frequency "f" is applied, any steady-state output of the circuit (the current through any component, or the voltage between any two points) is also sinusoidal with frequency "f".Informally, a linear circuit is one in which the electronic components' values (such as resistance, capacitance, inductance, gain, etc.