Enter Tank Circuit Values
Example Data Table
| Use Case | Inductance | Capacitance | Resistance | Approx Resonance | Typical Note |
|---|---|---|---|---|---|
| RF tuning | 10 µH | 100 pF | 2 Ω | 5.03 MHz | High frequency narrow tuning |
| Audio filter study | 50 mH | 1 µF | 15 Ω | 711.76 Hz | Low frequency response check |
| Oscillator tank | 2.2 µH | 47 pF | 1 Ω | 15.65 MHz | Common small signal design |
| Power resonance | 100 µH | 10 nF | 0.5 Ω | 159.15 kHz | Useful for switching circuits |
Formula Used
The calculator uses standard LC tank circuit equations. Resonant frequency is calculated as:
f₀ = 1 / (2π√LC)
Angular frequency is:
ω₀ = 2πf₀
Inductive and capacitive reactance are:
Xᴸ = 2πfL and Xᶜ = 1 / (2πfC)
For a series circuit, quality factor is:
Q = ω₀L / R
For a parallel circuit, quality factor is:
Q = R / (ω₀L)
Bandwidth is estimated by:
BW = f₀ / Q
Stored energy is calculated from peak values:
Eᴄ = 0.5CV² and Eᴸ = 0.5LI²
How to Use This Calculator
- Select the calculation mode.
- Choose series or parallel tank topology.
- Enter inductance, capacitance, resistance, and units.
- Enter a target frequency when solving for a missing component.
- Add a test frequency to inspect off-resonance impedance.
- Enter RMS voltage and current for stored energy estimates.
- Press the calculate button.
- Review the results above the form.
- Use the graph to compare impedance across frequency.
- Download CSV or PDF for records.
LC Tank Circuit Design Guide
What an LC Tank Does
An LC tank circuit stores energy between an inductor and a capacitor. The capacitor stores energy in an electric field. The inductor stores energy in a magnetic field. When connected together, energy moves back and forth between both parts. This exchange creates resonance at one main frequency.
Why Resonance Matters
Resonance is useful in filters, oscillators, radio receivers, transmitters, impedance networks, and tuning stages. At the resonant point, inductive reactance and capacitive reactance are equal. Their effects cancel in an ideal circuit. Real circuits include resistance. That resistance controls loss, bandwidth, and selectivity.
Series and Parallel Behavior
A series LC circuit has minimum impedance near resonance. Current can become high when resistance is low. A parallel LC circuit has maximum impedance near resonance. It can block a narrow frequency band or support oscillator action. Selecting the correct topology depends on the job.
Quality Factor and Bandwidth
Quality factor, called Q, tells how sharp the resonance is. A high Q circuit has narrow bandwidth. It rejects nearby frequencies better. A low Q circuit has wider bandwidth. It responds over a broader range. Resistance, coil losses, capacitor losses, and load resistance all affect Q.
Using Practical Values
Real inductors have winding resistance. Real capacitors have equivalent series resistance. Board traces also add stray inductance and capacitance. These small effects matter at high frequency. Use realistic values when designing radio or switching circuits. Always verify the final design with measurement.
Energy and Safety
The stored energy values help estimate stress on components. High voltage can appear across the capacitor. High current can flow through the inductor. Choose parts with enough voltage, current, and temperature margin. This calculator gives a strong design estimate, but testing remains important.
FAQs
1. What is an LC tank circuit?
An LC tank circuit combines an inductor and capacitor. It stores and exchanges energy between magnetic and electric fields. This creates a natural resonant frequency.
2. What does resonant frequency mean?
Resonant frequency is the frequency where inductive and capacitive reactance are equal. At this point, the circuit shows its strongest tuning behavior.
3. What is Q factor?
Q factor measures resonance sharpness. Higher Q means narrower bandwidth and lower loss. Lower Q means wider bandwidth and stronger damping.
4. Why does resistance matter?
Resistance represents losses in wires, coils, capacitors, and loads. It reduces Q, increases damping, and changes the useful bandwidth of the tank.
5. Can this calculator solve missing inductance?
Yes. Select the mode for finding inductance. Enter capacitance and target frequency. The calculator returns the required inductance value.
6. Can this calculator solve missing capacitance?
Yes. Select the mode for finding capacitance. Enter inductance and target frequency. The calculator returns the required capacitance value.
7. Is the graph based on selected topology?
Yes. The graph changes for series or parallel operation. It plots impedance over a frequency range around the calculated resonance.
8. Are real component losses included?
The calculator includes entered resistance. It does not automatically model every stray effect. Add realistic resistance for better practical estimates.