Efficiency of class b push pull amplifier

Push-pull amplifiers are the combinations of two bipolar junction transistor s that is one of P-N-P type and the other is of N-P-N type. In this combination one act as push type and the other acts as pull type. But where the higher values of efficiency are concerned then these amplifiers with two stages are utilized. One stage is referred to as push where the positive half of the cycle is utilized and at the pull stage, the negative cycle is utilized. A amplifier designed with two stages where one is utilizing the positive cycle that is referred to as the push stage and the negative cycle can be pulled at another stage.

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Content:

• Class B Push Pull Amplifier
• Push–pull output
• 9.2: The Class B Configuration
• CLASS B and Class AB Push Pull Amplifier
• Class b push pull amplifier diagram
• What is the overall efficiency of class B push pull amplifier?
• Module 5.3
• What is a Push-pull Amplifier : Circuit Diagram and Its Working Principle

WATCH RELATED VIDEO: Lec-160 Efficiency of Class B Power Amplifier-Derivation - A E - R K Classes - Hindi -

Class B Push Pull Amplifier

The Web This site. In amplifiers using class B bias, illustrated in Fig. This dramatically increases efficiency, compared with class A. The downside for this increased efficiency is that the transistor only amplifies half the waveform, therefore producing severe distortion. However, if the other half of the waveform can be obtained in some other way without too much distortion, then class B amplifiers can be used to drive most types of output device.

The aim is to obtain a good power gain with as much of the energy consumed from the power supply going into the load as possible. This should be as consistent with reasonable linearity lack of distortion , as possible. Power output stages do however produce more distortion than do voltage or current amplifiers. The circuit in Fig 5.

This method is only suitable at RF, as at lower frequencies the inductors and capacitors needed for the resonant circuit would be too large and costly for most applications. Because of the superior efficiency of class B it is a popular choice for power amplifiers, but to overcome the severe distortion caused by class B, audio amplifiers use a push-pull circuit. At lower e. The principles of this circuit are shown in Fig. Two identical but anti phase signals from a phase splitter are fed to the bases of a pair of power transistors so that each transistor conducting only when the half cycle during which its input wave goes positive , feeds current to the load for that half cycle.

The two half cycles are reh-combined in this circuit via a centre tapped transformer, which reverses the action of the phase splitter transformer, to produce a complete sine wave in the secondary. As shown in Fig. The effect of this distortion on the output depends to some degree on the amplitude of the output signal, the larger the amplitude the less significant the missing 1.

The large and varying current drawn by a powerful class B amplifier also puts considerable extra demand on the DC power supply and as the current drawn varies with the amount of signal applied, the smoothing capabilities of the power supply must be efficient enough to prevent this varying current from creating voltage changes at audio frequencies on the power supply lines. If these are not adequately removed, unintended audio feedback into earlier amplifier stages can occur and cause problems with instability.

This extra demand on power supply complexity adds to the cost of class B power amplifiers. Hons All rights reserved. Revision Learn about Electronics - Amplifiers.

Amplifier Basics 2. Class A Amplifier Design 3. Amplifier Circuits 5. Power Amplifiers 6. Operational Amplifiers. Module 5. After studying this section, you should be able to: Understand the operation of class B power amplifiers. List advantages and disadvantages of class B amplifiers. Fig 5. Crossover Distortion Fig 5.

Push–pull output

The Web This site. In amplifiers using class B bias, illustrated in Fig. This dramatically increases efficiency, compared with class A. The downside for this increased efficiency is that the transistor only amplifies half the waveform, therefore producing severe distortion.

9.2: The Class B Configuration

Click to see full answer. Likewise, what is the efficiency of Class B amplifier? Since the active device is switched off for half the input cycle, the active device dissipates less power and hence the efficiency is improved. Theoretical maximum efficiency of Class B power amplifier is One may also ask, why push pull amplifier operation is highly efficient? The advantages of push pull amplifier are low distortion, cancellation of power supply ripples and absence of magnetic saturation in the coupling transformer core which results in the absence of hum while the disadvantages are the need of two identical transistors and the requirement of bulky and costly coupling. The class B amplifiers are the positive and negative halves of the signals, that are allocated to the different parts of the circuits and the output device switched ON and OFF continuously. The basic class B amplifiers are used in two complementary transistors which are FET and bipolar. Class AB push pull amplifier. Which amplifier has highest efficiency?

CLASS B and Class AB Push Pull Amplifier

A push pull amplifier is an amplifier which has an output stage that can drive a current in either direction through through the load. The output stage of a typical push pull amplifier consists of of two identical BJTs or MOSFETs one sourcing current through the load while the other one sinking the current from the load. Push pull amplifiers are superior over single ended amplifiers using a single transistor at the output for driving the load in terms of distortion and performance. A single ended amplifier, how well it may be designed will surely introduce some distortion due to the non linearity of its dynamic transfer characteristics. Push pull amplifiers are commonly used in situations where low distortion, high efficiency and high output power are required.

Class b push pull amplifier diagram

Search How to Titles Subjects Organizations. Title: Large Signal Amplifier Objectives: - Understand the importance of amplifier efficiency - Know the most common classes of power amplifier and their basic characteristics Figure Large signal amplifier The early stages of amplifier systems are dealing with small signals. These stages are designed to give good voltage gain. Small signal transistors have a power rating of less than half a watt and power transistors have a power rating of more than half a watt. The later stages of an amplifier system have much larger collector currents, because the load impedances are much smaller i.

What is the overall efficiency of class B push pull amplifier?

Push-Pull Amplifier is a power amplifier which is used to supply high power to the load. One transistor pushes the output on positive half cycle and other pulls on negative half cycle, this is why it is known as Push-Pull Amplifier. The advantage of Push-Pull amplifier is that there is no power dissipated in output transistor when signal is not present. Class A configuration is the most common power amplifier configuration. It consists of only one switching transistor which is set to remain ON always. It produces minimum distortion and maximum amplitude of output signal. The stages of the Class A amplifier allows same amount of load current to flow through it even when there is not input signal connected, therefore large heatsinks are needed for the output transistors. The circuit diagram for Class A amplifier is given below:.

Module 5.3

Class B Amplifier — The inefficiency of Class-A amplifiers is largely due to the transistor bias conditions. In a Class-B amplifier, the transistors are biased to cutoff, so that there is no transistor power dissipation when there is no input signal. The output stage of a Class-B transformer-coupled amplifier is shown in Fig. Note that the supply is connected to the center-tap of the transformer primary, and that Q 2 and Q 3 have grounded emitters.

What is a Push-pull Amplifier : Circuit Diagram and Its Working Principle

RELATED VIDEO: Efficiency of class B push pull amplifier

A push—pull amplifier is a type of electronic circuit that uses a pair of active devices that alternately supply current to, or absorb current from, a connected load. This kind of amplifier can enhance both the load capacity and switching speed. Push—pull outputs are present in TTL and CMOS digital logic circuits and in some types of amplifiers , and are usually realized by a complementary pair of transistors , one dissipating or sinking current from the load to ground or a negative power supply, and the other supplying or sourcing current to the load from a positive power supply. A push—pull amplifier is more efficient than a single-ended "class-A" amplifier.

Which of these is not true for a class B amplifier? It has zero DC bias B. They have an efficiency less than that of class A amplifiers C. The quiescent power dissipation is zero D. Each transistor conducts when the input is greater than the base-emitter voltage. They have higher efficiency than class A amplifiers. What is the output of a class B amplifier for sinusoidal input?

Cite this Simulator:. Function generator, CRO, Regulated Power supply, pnp and npn transistors ,resistance, connecting wires. Push pull amplifier circuit design has been implemented on the virtual breadboard using following specifications:.