LCkrets

LCkrets, or LC circuit, is a passive electrical network that stores energy in the magnetic field of inductors and the electric field of capacitors. It typically contains at least one inductor (L) and one capacitor (C) connected in series or parallel. In a series LC circuit, the same current flows through both components; in a parallel LC circuit, the same voltage is across both. In an ideal LC circuit, the impedance is purely reactive except at resonance.

The circuit exhibits a characteristic resonance frequency given by f0 = 1/(2π√(LC)) and angular frequency ω0 = 1/√(LC). At this frequency the reactive effects of the inductor and capacitor cancel, so the impedance becomes purely resistive in the ideal case (series resonance yields minimum impedance, while parallel resonance yields maximum impedance). Energy continuously oscillates between the magnetic field of the inductor and the electric field of the capacitor, with the total energy remaining constant in an ideal circuit. The quality factor (Q) and bandwidth describe how sharply the circuit responds around resonance; real components introduce losses that damp the oscillations.

LCkrets are widely used in radio frequency and signal processing applications. They serve as tuning elements in receivers and transmitters, as band-pass and notch filters, and as frequency-determining elements in oscillators. They can also be employed for impedance matching and selective filtering in communication systems. In practice, non-idealities such as equivalent series resistance of coils, equivalent series or parallel resistances of capacitors, stray capacitances, and parasitic inductances must be accounted for, which affect resonance frequency and quality.