LC Tank Circuit

An LC tank circuit, also known as an LC resonant circuit or tuned circuit, is a fundamental electronic component in RF oscillators that combines an inductor (coil) and a capacitor to create a resonant frequency determined by the formula f = 1/(2π√(LC)). This circuit exhibits maximum impedance at its resonant frequency, allowing it to selectively amplify or generate signals at that specific frequency while attenuating others. In RF oscillators, it serves as the frequency-determining element that establishes stable oscillation through energy exchange between the magnetic field of the inductor and the electric field of the capacitor.

The LC tank circuit operates on the principle of electromagnetic resonance. When energized, electrical energy oscillates between the inductor's magnetic field and the capacitor's electric field at a natural resonant frequency. The inductor stores energy in its magnetic field when current flows through it, while the capacitor stores energy in its electric field when voltage is applied across it. This energy exchange creates continuous oscillation at the resonant frequency, with losses compensated by the oscillator's active components to maintain sustained oscillation.