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Title Hydrid Digital-Analog Feedback Audio Amplifiers
Author Rasmussen, Crilles Bak
Supervisor Larsen, Jan (Department of Informatics and Mathematical Modeling, Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark)
Institution Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark
Thesis level Master's thesis
Year 2004
Abstract This thesis is concerned with the topic of digital control of the power stage of a Class D amplifier with digital input. The thesis contains an examination of the error sources in the analog power stage, where the main contributors to distortion are identified. The analog control system for digital class D amplifiers, PEDEC, is explained, and it's influence on the amplifiers performance is shown. The two digital modulation forms dAIM and WPWM are described. The quantization noise caused by ¢§ modulation is examined as both modulators contain elements of the [ ] modulator. A Simulink model is implemented in MATLAB, to allow for simulation of modulator and power stage. This model is verified against existing real amplifiers, and serves as a simulation platform for development of control systems. The demands on digital control systems is determined in terms of allowable delay and required bandwidth. Two forms of feedback are discussed and implemented in Simulink, using the previous designed amplifier model. The first model is with a simple feedback of timing information, while the second is with feedback of amplitude information as well. The second is designed by discretizing the analog control system PEDEC. In Danish: Denne rapport omhandler emnet digital regulering af effekttrinnet i en klasse D forstærker med digitalt input. Rapporten indeholder en gennemgang af fejl-kilderne i det analoge effekttrin, og de største bidragydere til forvrænging bliver identificerede. Det analoge reguleringssystem, PEDEC, til digitale klasse D forstærker er forklaret, og der er redegjort for dets inflydelse på forstærkerens performance. De to digitale modulationsmetoder dAIM og WPWM bliver beskrevet. Da begge modulatorer indeholder elementer af [ ] modulatoren er kvantiserings- støjen forårsaget af denne modulering blevet undersøgt. En Simulink model er blevet implementeret i MATLAB for at kunne simulere både modulator og effekttrin. Denne model er blevet sammenlignet med virkelige forstærkere og tjener som evalueringsgrundlag for test af reguleringssystemer. Kravene til et digitalt reguleringssystem bliver bestemt udfra den krævede båndbredde, og den tilladelige forsinkelse. To forskellige feedback metoder bliver diskuteret, og bliver ved hjælp af den designede forstærkermodel implementeret i Simulink. Den første model anvender et simpelt feedback af timinginformation. Den anden model anvender et feedback af amplitudeinformation. Reguleringssystemet i det andet system er skabt ved at diskretisere det analoge system PEDEC.
Imprint Department of Informatics and Mathematical Modeling, Technical University of Denmark, DTU : DK-2800 Kgs. Lyngby, Denmark
Fulltext
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Admin Creation date: 2006-06-22    Update date: 2012-12-21    Source: dtu    ID: 154797    Original MXD