RLC series-parallel resonant circuit characteristics - high frequency study notes

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Resonance

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In physics, there is a concept called resonance: When the frequency of the driving force (the force may be outside pressure) and the natural frequency of the system is equal, the system of forced vibration amplitude maximum, a phenomenon called resonance. In the resonant circuit This is the meaning: when the natural frequency of the circuit is equal to the excitation frequency, the amplitude of the electromagnetic oscillation circuit will reach a peak. In fact, the expression of resonance and resonance is the same kind of phenomenon. This phenomenon has the same substance have different names in different areas of it.

Take Mu American Bridge by strong winds blowing resonance collapse.

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Series resonant circuit

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Energy stored in the circuit is constant, only inductors and capacitors (: so-called "resonance" refers only to transmit and receive energy conversion, no energy) between; plus emf loop only provides resistance consumes energy to maintaining the amplitude of the resonant circuit, the maximum current and the resonant tank.

At resonance, the minimum value of the loop impedance, i.e. Z = R; resonance, the inductor, the same frequency and power frequency current change across the capacitor, the equivalent of a short circuit

Characteristics:
1. The resonant frequency
when the imaginary part of the impedance of the reactance is zero, $wL-\frac{1}{wC}=0$ , have a resonant frequency $\bm{w_{0}=\frac{1}{\sqrt{LC}}}$The signal frequency is $ $\bm{f_{0}=\frac{1}{2\pi\sqrt{LC}}}$

2. The quality factor

Quality factor $Q=\bm{\frac{wL}{R}=\frac{1}{wCR}}$

Series resonance, the voltage across the capacitor and the inductor is equal to the size of the modulus value, and is equal to the applied voltage of Q times .

3. passband

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Parallel resonant circuit

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Parallel resonance, inductive, capacitive branch equivalent open

Quality factor:

Parallel resonance, the current flowing through the mode value of inductance and capacitance magnitude similar to the opposite direction, and is approximately equal to Q times the applied current

With a load equivalent quality factor:

Passband:

characteristic resonance same series, Q, the more narrow bandwidth.