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Power Amplifier

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References & Circuit Simulator

Can be downloaded from;

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  1. http://elearning.utm.my/22232/
  2. https://people.utm.my/rasli1/

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Circuit simulator: Multisim

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Observation

  • [2]p683-p721
  • [1]p339-p365

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Power Amplifier

Class A

Class B

Class AB

Class C

Amplifier Distortion and Heat Sinking Technique

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Basic Circuit for Class A

- Output signal is 360o of input signal and the amplifier gain is small-

-Input Power (Pin(dc))

-Output Power (Po(ac))

-Amplifier Efficiency

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Improved Circuit for Class A

- Output signal is 360o of input signal but the amplifier gain is better than the basic-

-Input Power (Pin(dc))

-Output Power (Po(ac))

-Amplifier Efficiency

-New load (R’L)

-Tx ratio

-Dissipated Power (PQ)

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Basic Circuit for Class B

- Output signal is more than 180o of input signal and the amplifier gain is medium-

-Input Power (Pi(dc))

-Output Power (Po(ac))

-Amplifier Efficiency

-Max Input Power (Pi(dc)max)

-Max Output Power(Po(ac)max)

-Max Amplifier Efficiency

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Push-Pull Circuit for Class B

- Output signal is 360o of input signal and the amplifier gain is medium-

-Input Power (Pi(dc))

-Output Power (Po(ac))

-Amplifier Efficiency

-Max Input Power (Pi(dc)max)

-Max Output Power (Po(ac)max)

-Max Amplifier Efficiency

-Max Dissipated Power

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Class AB

  • Max output voltage
  • Max output current

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Basic Circuit for Class C

- Output signal is more than 180o of input signal and the amplifier gain is highest-

-Average Dissipated Power (PD(avg))

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Tuned Circuit for Class C

- Output signal is more than 180o of input signal and the amplifier gain is highest at resonant frequency-

-Amplifier Efficiency

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Clamped Circuit for Class C

- Output signal is more than 180o of input signal and the amplifier gain is highest at resonant frequency-

-Amplifier Efficiency

-Max output voltage

-Resonant frequency

-Base voltage (Vs(p))

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Amplifier Distortion

  • Output signal is not purely sinusoidal waveform, it more less than 360o. It forms in series of harmonic due to noon linearity devices.
  • Other word, output signal consists of fundamental frequency, and integer multiples are harmonic signals.
  • Harmonic distortion, second harmonic and total harmonic distortion.

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Heat Sinking Technique

  • A metal to attach to the power amplifier for the purpose of absorbing heat from the device.
  • Maximum Dissipated Power (PDmax)

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Problems/Examples

Look at given problems;

-[2]p688, example 12.1

-[2]p690, example 12.3

-[2]p694, example 12.5

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Some Important Points on�Class A Power Amplifier

-Input Power (Pin(dc))

-Output Power (Po(ac))

-Amplifier Efficiency

-New load (R’L)

-Tx ratio

-Dissipated Power (PQ)

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Problems/Examples

Look at given problems;

*[2]p697, example 12.7

*[2]p699, example 12.9

*[2]p705, example 12.11

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Some Important Points on�Class B Power Amplifier

-Input Power (Pi(dc))

-Output Power (Po(ac))

-Amplifier Efficiency

-Max Input Power (Pi(dc)max)

-Max Output Power (Po(ac)max)

-Max Amplifier Efficiency

-Max Dissipated Power

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Problems/Examples

Look at given problems;

*[1]p351, example 7-3

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Some Important Points on�Class AB Power Amplifier

-Max Output Voltage

-Max Output Current

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Problems/Examples

Look at given problems;

*[1]p359, example 7-7

*[1]p363, example 7-8

*[1]p365, example 7-9

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Some Important Points on�Class C Power Amplifier

-Average Dissipated Power (PD(avg))

-Amplifier Efficiency

-Max output voltage

-Resonant frequency

-Base voltage (Vs(p))

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Problems/Examples

Look at given problems;

*[2]p706, example 12.13

*[2]p708, example 12.15

*[2]p708, example 12.16

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Some Important Points on�Power Amplifier Distortion

-Harmonic distortion

-Second harmonic

-Total harmonic distortion.

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Problems/Examples

Look at given problems;

*[2]p710, example 12.17

*[2]p712, example 12.18

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Some Important Points on�Heat Sinking Technique

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-Maximum Dissipated Power (PDmax)

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Multisim Simulation 2

  • Please refer to [2]p721,
  • Problem 26
  • Problem 27
  • Problem 28

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Please, provide the answer from your simulation using multisim package for the 3 problems

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The End�Thanks