LC Resonant Frequency Calculator – Tank Circuit & Q Factor
An inductor and a capacitor trade energy back and forth at one frequency. This is the heart of oscillators, RF matching networks and many filters.
H
= 10 µH10u = 10 µHF
= 100 pF100p = 100 pFΩ
Results
- Resonant frequency f₀
- 5.033 MHz
- Angular frequency ω₀
- 31.62 Mrad/s
- Characteristic impedance √(L/C)
- 316.2 Ω
- Reactance at f₀ (XL = XC)
- 316.2 Ω
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Resonant frequency f₀: 5.033 MHz
Formula
- f0 = 1 / (2π·√(L·C))
- Z0 = √(L/C)
- Q = Z0 / R (series RLC)
FAQ
- Does the PCB add capacitance?
- Yes. Stray capacitance of a few pF can shift high-frequency resonances noticeably. Measure and trim.
- What sets the Q factor?
- Losses: the inductor's DC resistance, core losses and capacitor ESR. Lower resistance means higher Q and narrower bandwidth.