‫ﭼﮑﯿﺪه‬
‫ﺑﺮرﺳﯽ‪ ،‬ﻣﺪلﺳﺎزي و ﺷﺒﯿﻪﺳﺎزي ﺗﮑﻨﯿﮏﻫﺎي اﺧﯿﺮ ﺧﻄﯽﺳﺎزي ﺗﻘﻮﯾﺖﮐﻨﻨﺪه ﮐﻼس‪D-‬‬
‫و اراﺋﻪ و آﻧﺎﻟﯿﺰ ﯾﮏ ﺗﮑﻨﯿﮏ ﺧﻄﯽﺳﺎزي ﺟﺪﯾﺪ‬
‫ﺑﻪ ﮐﻮﺷﺶ‬
‫ﻣﺤﻤﺪ ﻫﻮﺷﯿﺎر‬
‫اﻣﺮوزه ﺑﻪ دﻟﯿﻞ ﻗﺎﺑﻞ ﺣﻤﻞ ﺷﺪن درﺻﺪ ﻗﺎﺑﻞ ﺗﻮﺟﻬﯽ از ﻣﺤﺼﻮﻻت اﻟﮑﺘﺮوﻧﯿﮑﯽ‪ ،‬ﺑﺎزده ﺗﻮاﻧﯽ ﺑﺎﻻ‬
‫در اﯾﻦ ﻣﺤﺼﻮﻻت ﺑﺴﯿﺎر ﻣﻬﻢ ﺷﺪه اﺳﺖ‪ .‬ﺗﻘﻮﯾﺖﮐﻨﻨﺪهﻫﺎي ﺻﻮﺗﯽ ﮐﻼس‪ D-‬ﻣﯽﺗﻮاﻧﻨﺪ ﺗﺎ ﺣﺪ زﯾﺎدي‬
‫اﯾﻦ ﻧﯿﺎز را در ﺑﺨﺶ ﺻﻮﺗﯽ ﺑﺮ ﻃﺮف ﮐﻨﻨﺪ‪ .‬ﺑﺎ اﯾﻦ ﺣﺎل ﯾﮑﯽ از ﻣﺸﮑﻼت اﺻﻠﯽ اﯾﻦ ﺗﻘﻮﯾﺖﮐﻨﻨﺪهﻫﺎ‬
‫ﻣﺴﺌﻠﻪ اﻋﻮﺟﺎج ذاﺗﯽ اﺳﺖ‪.‬‬
‫در اﯾﻦ ﭘﺎﯾﺎنﻧﺎﻣﻪ ﺑﺎ ﺗﻤﺮﮐﺰ ﺑﺮ اﻋﻮﺟﺎج ذاﺗﯽ اﺑﺘﺪا ﺑﻪ ﻣﺮور ﻣﻔﺎﻫﯿﻢ ﭘﺎﯾﻪ ﺗﻘﻮﯾﺖﮐﻨﻨﺪهﻫﺎي ﮐﻼس‪-‬‬
‫‪ D‬و ﺗﻌﺪادي از ﺗﮑﻨﯿﮏﻫﺎي ﮔﺰارش ﺷﺪه ﺑﺮاي ﮐﺎﻫﺶ اﻋﻮﺟﺎج ﭘﺮداﺧﺘﯿﻢ‪ .‬در اداﻣﻪ ﺑﺎ ﺑﻪﮐﺎرﮔﯿﺮي‬
‫آﻧﺎﻟﯿﺰ ﺗﺌﻮري اﺧﺘﻼل ﻧﺤﻮه اﺳﺘﺨﺮاج ﻣﺪل رﯾﺎﺿﯽ ﺑﺮاي ﺳﺎﺧﺘﺎر ﺳﻨﺘﯽ ﺑﺎ ﻣﺪوﻻﺗﻮر ‪ PWM‬را ﺗﺸﺮﯾﺢ‬
‫ﮐﺮده و ﻧﺸﺎن دادهاﯾﻢ ﮐﻪ اﻋﻮﺟﺎج ذاﺗﯽ ﭼﻄﻮر در ﻣﺪل رﯾﺎﺿﯽ ﻇﺎﻫﺮ ﻣﯽﺷﻮد‪ .‬ﺳﭙﺲ ﺿﻤﻦ ﻣﻌﺮﻓﯽ‬
‫دو ﻓﯿﻠﺘﺮ ﻣﯿﺎﻧﮕﯿﻦ ﻣﺘﺤﺮك )‪ SMA‬و ‪ (IMA‬و وﯾﮋﮔﯽ ﺷﮑﺎفﻫﺎي ﻓﺮﮐﺎﻧﺴﯽ ﻣﺘﻮاﻟﯽ اﯾﻦ ﻓﯿﻠﺘﺮﻫﺎ‪،‬‬
‫ﻧﺤﻮه ﺑﻪﮐﺎرﮔﯿﺮي آنﻫﺎ در ﺳﺎﺧﺘﺎر ﺳﻨﺘﯽ ﺑﺎ ﻫﺪف ﮐﺎﻫﺶ اﻋﻮﺟﺎج ﻫﺎرﻣﻮﻧﯿﮑﯽ را ﺑﯿﺎن ﮐﺮده و ﺑﺎ‬
‫آﻧﺎﻟﯿﺰ ﺗﺌﻮري اﺧﺘﻼل‪ ،‬ﻣﺪل رﯾﺎﺿﯽ ﺳﺎﺧﺘﺎرﻫﺎي ﺟﺪﯾﺪ ﺑﺎ ﻫﺮ ﯾﮏ از اﯾﻦ دو ﻓﯿﻠﺘﺮ را اﺳﺘﺨﺮاج ﮐﺮدهاﯾﻢ‪.‬‬
‫ﺑﺎ ﺑﺮرﺳﯽ و ﺷﺒﯿﻪﺳﺎزي ﻣﺪل ﺑﻠﻮك دﯾﺎﮔﺮاﻣﯽ و ﻣﺪل رﯾﺎﺿﯽ ﺑﺮاي ﺳﺎﺧﺘﺎرﻫﺎي ﺳﻨﺘﯽ و ﺟﺪﯾﺪ ﻧﺸﺎن‬
‫دادﯾﻢ ﮐﻪ ﻣﺪلﻫﺎي رﯾﺎﺿﯽ دﻗﺖ ﺑﺎﻻﯾﯽ داﺷﺘﻪ و اﻋﻮﺟﺎج ﻫﺎرﻣﻮﻧﯿﮑﯽ ﮐﻞ )‪ (THD‬ﺑﺎ ﺣﻀﻮر ﻓﯿﻠﺘﺮﻫﺎي‬
‫‪ SMA‬و ‪ IMA‬ﺑﻪ ﺗﺮﺗﯿﺐ ﺣﺪود ‪ 12 dB‬و ‪ 20 dB‬ﺑﻬﺒﻮد ﯾﺎﻓﺘﻪ اﺳﺖ‪ .‬در آﺧﺮ ﻧﯿﺰ ﺿﻤﻦ ﺑﺤﺚ در‬
‫ﻣﻮرد ﭼﺎﻟﺶﻫﺎي ﻃﺮاﺣﯽ ﻋﻤﻠﯽ از ﺟﻤﻠﻪ ﻧﻮﯾﺰ ﺗﻘﻮﯾﺖﮐﻨﻨﺪه و ﻣﺪار ﻣﻮﻟﺪ ﺗﺄﺧﯿﺮ ﺑﻪ اراﺋﻪ راﻫﮑﺎرﻫﺎي‬
‫ﻋﻤﻠﯽ ﺑﺮاي ﻫﺮ ﯾﮏ ﭘﺮداﺧﺘﻪاﯾﻢ‪.‬‬
‫واژﮔﺎن ﮐﻠﯿﺪي‪ :‬اﻋﻮﺟﺎج ﻫﺎرﻣﻮﻧﯿﮑﯽ‪ ،‬ﺗﺌﻮري اﺧﺘﻼل‪ ،‬ﺗﻘﻮﯾﺖﮐﻨﻨﺪه ﮐﻼس‪ ،D-‬ﻓﯿﻠﺘﺮ ﻣﯿﺎﻧﮕﯿﻦ‬
‫ﻣﺘﺤﺮك‪.‬‬
‫ح‬
Abstract
Investigation, Modeling and Simulation of Recent Class-D Amplifier
Linearization-Techniques and Presenting and Analyzing a New Linearization
Technique
By
Mohammad Hooshiar
Nowadays, due to the portability of a significant percentage of electronic products,
high power efficiency has become very important in these products. Class-D audio
amplifiers can largely eliminate this need in the audio section. However, one of the
main problems of these amplifiers is the issue of intrinsic distortion.
In this thesis, by focusing on intrinsic distortion, we first reviewed the basic
concepts of class-D amplifiers and a number of reported techniques to reduce
distortion. In the following, we have explained how to derive the mathematical model
for a traditional structure with a PWM modulator by applying the analysis of
perturbation theory and shown how the intrinsic distortion appears in the
mathematical model. Then, while introducing two moving average filters (SMA and
IMA) and the characteristic of the sequential frequency notchs of these filters, we have
explained how to use them in the traditional structures with the aim of reducing
harmonic distortion and by analyzing the perturbation theory, we have derived the
mathematical model of new structures with each of these two filters. By investigating
and simulating the block diagram model and the mathematical model for traditional
and new structures, we showed that the mathematical models are highly accurate and
the total harmonic distortion (THD) has improved by 12 dB and 20 dB with the
presence of SMA and IMA filters, respectively. In the end, while discussing about
practical design challenges, including amplifier noise and delay generator circuit, we
have proposed the practical solutions for each one.
Keywords: Class-D Amplifier, Harmonic Distortion, Moving Average Filter,
Perturbation Theory