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Class D audio amplifier, also named switch amplifier, is used to transform the input analog audio signal or PCM digital information into pulse signal of PWM or PDM, and to control large power switch device to put through/cut off audio power amplifier.
The theoretical efficiency of class A audio amplifier is 25%, and its real efficiency is about 15-20%; the theoretical efficiency of class B is about 75%; the theoretical efficiency of class AB is about 75% as well with a real efficiency between 50%-70%; the theoretical efficiency of class D is about 100% with a real efficiency of more than 85%. The high efficiency of class D offers lots of advantages, such as power saving, which is quite important for MP3 and music mobile phones. Power saving means longer paying time, and can attract more clients. Another advantage is a smaller heat generation, which can reduce heat management costs. For instance, large power class AB amplifiers usually need radiator, but the as powerful class D amplifiers do not need it.
Efficiency Contrast between Class D Audio Amplifier and Class AB Audio Amplifier
The class D audio amplifier circuit is has a comparably smaller size. Besides, under most conditions, it does not need any heat sinks; therefore, the entire size can be reduced greatly. It is quite important for car audio and mobile phone due to the strict size requirements.
Currently, there are 108 varieties of class D audio IC. The above figure is the product classifications and shares for each manufacturer. The audio amplifier IC markets, which are sensitive to volume, efficiency etc, such as mobile phones, portable audio/video players, flat screen televisions, projection televisions, car audios, notebook computers etc, are all the potential markets of class D audio amplifier IC.
Class D audio amplifier IC also has many disadvantages such as EMI (Electro Magnetic Interference), distortion, narrow frequency response rage, narrow dynamic range, high power requirements and costs, etc.
Considering the mobile phone market, the major problems are EMI and cost. However, this market adopts platform strategy; and it is impossible to enter the market solely relying on class D audio amplifier IC. Therefore, the professional manufacturers of class D audio IC should aim at the markets of flat screen television, car audio and multi-channel audio. Considering those markets, the major problems are cost and timbre, especially the timbre. Δ-Σ should be used to improve the timbre. And ADI could be the best choice.
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2005-2008 www.researchinchina.com All Rights Reserved
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Class D audio amplifier, also named switch amplifier, is used to transform the input analog audio signal or PCM digital information into pulse signal of PWM or PDM, and to control large power switch device to put through/cut off audio power amplifier.
The theoretical efficiency of class A audio amplifier is 25%, and its real efficiency is about 15-20%; the theoretical efficiency of class B is about 75%; the theoretical efficiency of class AB is about 75% as well with a real efficiency between 50%-70%; the theoretical efficiency of class D is about 100% with a real efficiency of more than 85%. The high efficiency of class D offers lots of advantages, such as power saving, which is quite important for MP3 and music mobile phones. Power saving means longer paying time, and can attract more clients. Another advantage is a smaller heat generation, which can reduce heat management costs. For instance, large power class AB amplifiers usually need radiator, but the as powerful class D amplifiers do not need it.
Efficiency Contrast between Class D Audio Amplifier and Class AB Audio Amplifier
The class D audio amplifier circuit is has a comparably smaller size. Besides, under most conditions, it does not need any heat sinks; therefore, the entire size can be reduced greatly. It is quite important for car audio and mobile phone due to the strict size requirements.
Currently, there are 108 varieties of class D audio IC. The above figure is the product classifications and shares for each manufacturer. The audio amplifier IC markets, which are sensitive to volume, efficiency etc, such as mobile phones, portable audio/video players, flat screen televisions, projection televisions, car audios, notebook computers etc, are all the potential markets of class D audio amplifier IC.
Class D audio amplifier IC also has many disadvantages such as EMI (Electro Magnetic Interference), distortion, narrow frequency response rage, narrow dynamic range, high power requirements and costs, etc.
Considering the mobile phone market, the major problems are EMI and cost. However, this market adopts platform strategy; and it is impossible to enter the market solely relying on class D audio amplifier IC. Therefore, the professional manufacturers of class D audio IC should aim at the markets of flat screen television, car audio and multi-channel audio. Considering those markets, the major problems are cost and timbre, especially the timbre. Δ-Σ should be used to improve the timbre. And ADI could be the best choice.
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2005-2006 www.researchinchina.com All Rights Reserved |
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1. Brief Introduction of Class D Audio Amplifier 1.1 Basic principle of class D amplifier 1.2 Comparison between class D amplifier and other amplifiers 1.3 Advantages of class D audio amplifier 1.4 Disadvantages and resolutions of class D audio amplifier 1.4.1 EMI 1.4.2 Distortion improvement 1.4.3 Improvement of frequency response range and related distortion problems 1.4.4 Large inductance and capacitance of output LPF 1.4.5 High power requirement 2. Class D Audio IC Industry 2.1 Development of class D audio IC 2.2 Example of class D audio amplifier IC for mobile phone application 2.3 Application status of class D audio amplifier IC 3. Class D Audio Amplifier IC Market 3.1 Music mobile phone market 3.3 Portable audio/video player 3.4 Car audio 3.5 Flat screen television 3.6 Home audio system 3.7 PC Multi-media audio 4. Audio IC Manufacturers 4.1 YAMAHA 4.2 TI 4.3 National Semiconductor 4.4 Maxim 4.5 On Semiconductor 4.6 Philip 4.7 Microsemi 4.8 ST 4.9 CIRRUS 4.10 ADI 4.11 WOLFSON 4.12 New Japan Radio 4.13 ZETEX 4.14 AT CHIP 4.15 Monolithic Power 4.16 SIGMATEL 4.17 Power Analog Microelectronics 4.18 Tripath |
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2005-2008 www.researchinchina.com All Rights Reserved |
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Signal Generation Principle of PWM Principle of Class B Audio Amplifier Principle of Class AB Audio Amplifier Efficiency contrast between Class D Audio Amplifier and Class AB Audio Amplifier Δ-Σ Modulator Typical LPF circuit of Class D Audio Amplifier Quantity statistics of global major Class D Audio IC Internal frame of TI TPA2012D2 Internal frame of National Semiconductor LM4670 Internal frame of Maxim MAX9700 Internal frame of On Semiconductor NCP2820 Internal frame of TI TPA2005D1 Global shipment forecast of mobile phones Global shipment forecast of music mobile phones Quarterly shipment of China's music mobile phones in 2005 Shipment of MP3, MP4 mobile phones in China from 2005-2010 Global laptop shipment from 2001-2008 Global audio player shipment forecast Global PMP shipment forecast Global LCD TV sales from 2004-2009 Global plasma TV sales from 2004-2009 Global MD RPTV sales from 2004-2009 Brief Introduction of YAMAHA Class D Amplifier IC (single chip) products of YAMAHA Class D Amplifier Control IC of YAMAHA Feature contrast between Class D Amplifier of YAMAHA and other corporations Class D Amplifier product applications of YAMAHA Class D Audio Amplifier products of TI Class D Power Amplifier prodcuts of National Semiconductor Class D Super Bass Power Amplifier of National Semiconductor Class D Boomer Power Amplifier of National Semiconductor Class D Audio Amplifier products of Mexium Class D Amplifier products of On Semiconductor Class D Amplifier products of Philip Semiconductor Class D Amplififer products of Microsemi Main Clients of Microsemi Class D Amplifier Products of ST Audio Digital Amplifier Products of CIRRUS Class D Amplifier Parameter of ADI's AD199X Series of Class D Amplifier products of Wolfson Class D Amplifier Products of New Japan Radio Class D Amplifier products of ZETEX Semiconductor Class D Amplifier Products of Monolithic Power Integrated Audio Amplifier Products of Tripath Main Clients of Tripath
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2005-2008 www.researchinchina.com All Rights Reserved
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