InductorCapacitor

An inductorcapacitor, commonly referred to as an LC network or LC tank, is a circuit element or module that combines an inductor (L) and a capacitor (C) to form a resonant circuit. Such networks are used to select or generate specific frequencies, and appear in radio receivers, transmitters, and signal-processing equipment. They can be implemented as discrete components, integrated circuits, or as a combination of both.

The defining property is resonance: energy shuttles between the magnetic field of the inductor and the electric field of the capacitor. For an ideal LC circuit, the resonant frequency is f0 = 1/(2π√(LC)). In a series configuration, the impedance is minimized at resonance; in a parallel configuration, the impedance is maximized. The quality of resonance is described by the Q factor.

Common configurations include series LC and parallel LC networks. They serve as tuned circuits in radio-frequency front ends, as components in filters (band-pass or notch) and in oscillators. Integrated LC tanks are now found in RF ICs and surface-mount packages, including MEMS inductors and high-Q capacitors, enabling compact tuning solutions.

Practical considerations include parasitics such as equivalent series resistance (ESR) and inductance (ESL), stray capacitances, and temperature coefficients. These factors affect bandwidth, stability, and drift. Designers balance component quality, layout, and packaging with the required selectivity and power handling.