Dr. Mohamed Refky Amin

Electronics and Electrical Communications Engineering Department (EECE)

Cairo University

1st.year.circuits@gmail.com

http://scholar.cu.edu.eg/refky/

Resonance Circuits

Part II

Outline of This Lecture

• Previously on ELC 1030

• Examples on Series Resonance Circuits

• Parallel Resonance Circuits

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Previously on ELC 1030

In physics, resonance is the tendency of a system to oscillate with

greater amplitude at some frequencies than at others.

Frequency at which the response amplitude is a maximum is

known as the system's resonant frequency, or resonance frequency

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Definition of Resonance

3

Previously on ELC 1030

For electric circuit to resonate, the circuit must have L, and C

elements.

Resonance is a condition in an RLC circuit in which the capacitive

and inductive reactances are equal in magnitude, thereby resulting

in a purely resistive impedance.

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Resonance in Electrical Circuits

4

Previously on ELC 1030

Series Resonance Circuit Parallel Resonance Circuit

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Types of Resonance Circuits

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Resonant circuits (series or parallel) are useful for constructing

filters, as their transfer functions can be highly frequency selective.

They are used in many applications such as selecting the desired

stations in radio and TV receivers.

Previously on ELC 1030

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Applications of Resonance Circuits

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Previously on ELC 1030

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General Expression for the Current

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Previously on ELC 1030

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Previously on ELC 1030

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Previously on ELC 1030

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Previously on ELC 1030

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Previously on ELC 1030

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Previously on ELC 1030

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Previously on ELC 1030

Resonance at

-

in rad/s in Hz

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Series Resonance

Example (1)

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Series Resonance

Example (2)

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Series Resonance

Example (3)

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Series Resonance

Example (4)

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Series Resonance

Example (5)

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Parallel Resonance

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Ideal Parallel Circuit

Parallel Resonance

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In parallel circuits, at resonance,

the capacitor and the coil are

replaced by an Open Circuit.

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Ideal Parallel Circuit

Parallel Resonance

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Quality Factor of a Real Coil

Parallel Resonance

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Parallel Resonance

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The Equivalent All-Parallel Circuit

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Parallel Resonance

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The Equivalent All-Parallel Circuit

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Parallel Resonance

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The Equivalent All-Parallel Circuit

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Parallel Resonance

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The Equivalent All-Parallel Circuit

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Parallel Resonance

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The Equivalent All-Parallel Circuit

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Parallel Resonance

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Parallel Resonance

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• Impedance & voltage in terms of quality factor

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Parallel Resonance

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Parallel Resonance

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Parallel Resonance

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Bandwidth and Cut-off Frequencies

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Parallel Resonance

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Bandwidth and Cut-off Frequencies

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Parallel Resonance

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Bandwidth and Cut-off Frequencies

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Parallel Resonance

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Bandwidth and Cut-off Frequencies

a b c

1

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Parallel Resonance

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Bandwidth and Cut-off Frequencies

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Parallel Resonance

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Parallel Resonance

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Parallel Resonance

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In general:

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Resonance at

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Parallel Resonance