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esonanc

e&

Filters

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Resonanc

e

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Resonance

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Resonance

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Resonant

circuit

Is a circuit that achieves resonant condition by

varying the sources frequency.

Resonant

circuit

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T une d   c i r c ui t 

 Is a circuit thatachieves resonantcondition by varying acircuit parameter

(either L  or C).

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Imag [Zeg] = Imag [Yeg] = 0

ResonantCondition

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ResonantCondition

2. The magnitude o the

e!uivalent impedance (oradmittance) is either

"#$I"%"

"II"%"

 or series resonance

 or parallel or anti'resonance

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  at resonance the circuit acts as alo impedance and re!uencyselective netor 

Resonant Fre!uency*r (+,) -

here/ L - inductance ( + )

  C - capacitance ( F )

01RI10 Resonance

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$L

$c.

2.Circuit impedance (3) is minimum

4 3o 4

R "II"%"

Characteristics o 0eries Resonance

01RI10 Resonance

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5. Current (I) is ma6imum

Io "#$I"%"

Characteristics o 0eries Resonance

01RI10 Resonance

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CAPACII!"

#"$I$I!"

Characteristics o 0eries Resonance

01RI10 Resonance

I%&'CI!"

P(A$" A%)*"

+#", -hZfr

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/. is resistive

. At 1 is inductive

2. At 1 is ca3acitive

3

3re! 7 r 

3re! 8 r 

Characteristics o 0eries Resonance

01RI10 Resonance

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  also non as Figure o "erit

  it reers to the 9goodness: o a reactive

component  In series circuit/ the voltagemagni;cation actor at the time oresonance

<uality Factor (,)

<

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<

<

- -

-

<uality Factor (,)

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  # range o re!uencies taenbeteen to'hal poer pointshich operation is satisactory.

=andidth* = (+,)

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  # ord o caution is in order ith series LCresonant circuits/ because o the high

currents hich may be present in a series LCcircuit at resonance* it is possible to producedangerously high voltage drops across thecapacitor and the inductor* as eachcomponent possesses signi;cant impedance.

Resonant Rise in >oltage across L 

or C

 > L  -  >c  -  (< 

 6  >s )

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?#R#LL1L Resonance  At resonance1 the circuit acts as a highim3edance and a frequency se4ective net5or6

Vs R L C

Theoretical ?arallel Resonant

Circuit

Resonant Fre!uency

r (+,) -

here/ L - inductance( + )  C - capacitance( F )

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.Circuit impedance (3) is

3 R

"#$I"%"

2.Total current (I) is "II"%"

?#R#LL1L ResonanceCharacteristics of a heoretica4 Para44e4 #esonant

circuit

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?#R#LL1L ResonanceCharacteristics of a heoretica4 Para44e4 #esonant

circuit

CAPACII!"

#"$I$I!"

I%&'CI!"

P(A$" A%)*"

+#", -(7r

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8. is resistive

/. At 1 isca3acitive

. At 1 is

inductive

3

3re! 7 r 

3re! 8  r 

?#R#LL1L ResonanceCharacteristics of a heoretica4 Para44e4 #esonant

circuit

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<uality Factor (,)  also non as Figure o "erit

  In parallel circuit/ the current magni;cationactor at the time o resonance.

<

<

-

-

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=andidth* = (+,)

VsL

C

I (t)

Theoretical ?arallel Resonant Circuit

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Tuning Capacitance

Resonant re!uency* r* (+,)

@ynamic Impedance (3)*