A Comparative Study on Class AB and Class D Amplifier Topologies for High Temperature Power Line Communication Circuits

The High Temperature Gas-Cooled Reactor (HTGR) is developed widespread in the world nowadays. The helium turbine of the 10 MW high temperature gas-cooled test module reactor with the core made of spherical fuel elements is under research at the Institute of Nuclear and New Energy Technology of Tsinghua University in China. Magnetic bearings are widely applied in HTGR, where the rotating machineries are running under highly pure helium environment. Compared with conventional bearings, Active Magnetic Bearings (AMBs) possess several attractive advantages, such as contact-free, no-lubricating and active damping vibration. The sensors are the key components of the AMBs system and are responsible for measuring the position and movement of the rotor, the operating temperature and so on. In order to operate the sensors successfully, a stable and efficient excitation source is needed. The conventional excitation source, which is equivalent to the class AB power amplifier circuit, is inefficient and unstable in the previous experiment, and therefore a new source using class D power amplifier is under research and development. The paper will present the design, simulation and test of the new excitation source for the sensors of the AMBs system.

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PENGUAT KELAS D DENGAN METODE SUMMING INTEGRATOR

eLEKTRIKA ◽

10.26623/elektrika.v11i2.1693 ◽

2019 ◽

Vol 11 (2) ◽

pp. 12

Author(s):

Budihardja Murtianta

Keyword(s):

Main Part ◽

Pulse Width Modulation ◽

Audio Signal ◽

Switching Frequency ◽

Class Ab ◽

Sawtooth Wave ◽

Class D Amplifier ◽

Class D ◽

Class B ◽

Digital Encoding

A class D amplifier is one in which the output transistors are operated as switches. When a transistor is off, the current through it is zero and when it is on, the voltage across it is small, ideally zero. Thus the power dissipation is very low, so it requires a smaller heat sink for the amplifier. Class D amplifier operation is based on analog principles and there is no digital encoding of the signal. Before the emergence of class D amplifiers, the standard classes were class A, class AB, class B, and class C. The classic method for generating signals driving a transistor MOSFET is to use a comparator. One input is driven by an incoming audio signal, and the other by a triangle wave or a sawtooth wave at the required switching frequency. The frequency of a triangular or sawtooth wave must be higher than the audio input. MOSFET transistors work in a complementary manner that operates as a switch. Triangle waves are usually generated by square waves fed to the integrator circuit. So the main part of processing audio signals into PWM (Pulse Width Modulation) is the integrator and comparator. In this paper, we will discuss the work of a class D amplifier system using the summing integrator method as its main part.

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Design of Class D Audio Power Amplifier Suitable to Hearing Aid Devices

International Journal of Innovative Technology and Exploring Engineering - Special Issue ◽

10.35940/ijitee.b7327.019320 ◽

2020 ◽

Vol 9 (3) ◽

pp. 143-152

Keyword(s):

Power Amplifier ◽

Power Efficiency ◽

Hearing Aid ◽

Power Level ◽

Class Ab ◽

Class A ◽

Class D Amplifier ◽

Audio Amplifier ◽

Class D ◽

Audio System

An amplifier is an electronic circuit that improves the strength of the signal. Using an amplifier in an audio system is essential to improve the strength of the signal. Based on different applications and specifications different types of amplifiers are used. Generally in an audio system, the input signal is amplified to a minimum required power level and then the speaker is driven by it. Conventionally, the output stage of an audio amplifier uses Class-A or Class-AB operating in a linear transfer region. The power efficiency of the Class-D amplifier has a better output efficiency compared to Class-A and Class-AB amplifiers, and its distortion is lower than that of the Class-C amplifier. This is based on a known fact that the Class D amplifier has a switching action in which the transistors are either completely on or off. As a result, the amplification is achieved with no power dissipation. Hence, the size of the amplifier can be highly reduced and a smaller heat sink is required. This paper focuses on designing a Class-D power amplifier which is suitable for hearing aid devices to deliver 500mW output power and for the THD to be less than 3%. The circuit implementation is done using UMC high voltage 0.18μm technology. This amplifier consists of three stages such as the modulation stage, the driver stage, the bridge stage, and the demodulation stage. Unfortunately, the Class-D power amplifier has inherent non-linear distortion problems, which is more significant than conventional audio power amplifiers. In this thesis, negative feedback is employed to reduce THD. Without feedback, the THD is obtained as above 3%. By employing feedback, the THD was reduced by 1.96dB. This design result is discussed and through to realization; whereupon the effectiveness of each of the implementation is evaluated.

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Perbandingan Efisiensi Daya Penguat Audio Kelas AB dengan Penguat Audio Kelas D untuk Keperluan Sound System Lapangan

Jurnal Teknik Elektro ◽

10.15294/jte.v10i2.11183 ◽

2018 ◽

Vol 10 (2) ◽

pp. 54-58

Author(s):

Muhamad Kharis ◽

Dhidik Prastiyanto ◽

Suryono Suryono

Keyword(s):

Output Power ◽

Power Efficiency ◽

Input Power ◽

Sound System ◽

Class Ab ◽

Audio Amplifiers ◽

Class D Amplifier ◽

Audio Amplifier ◽

Class D ◽

Field Sound

Class AB audio amplifiers are commonly used but the efficiency is 50%. While the efficiency of class D audio amplifiers is 90% but are rarely used. The purpose of this research is to know how much the power efficiency of field sound system between 1000 watts class AB amplifier and 900 watts class D amplifier. This study is a comparative study that compares different variables with the same sample. The results of power efficiency are obtained from the percentage comparison between the output power and the input power of each audio amplifier. The power efficiency of class D audio amplifiers with IRS D900 type larger than class AB audio amplifiers with Apex B500 type. The efficiency value of class D audio amplifiers at the highest output power reaches 87% while class AB audio amplifiers are only 73%.

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