CS-EE 481 Spring 2007

Founder’s Day, 2007 1University of Portland School of Engineering

Sublimity AudioStereo Class-D Audio Amplifier

AuthorsJoe Baird

Luke Raynor

Aaron Taylor

AdvisorDr. Osterberg

Industry RepresentativeMr Mike Desmith

Intel

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Introduction

• Why Class-D?

– Higher Efficiency amplifier

– Important to mobile electronics

– Efficiency less heat smaller size

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Important Things to Note

• Reasons Class-D is so efficient

• Basic idea behind the amplifier

• Importance of proper layout

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Simple Class AB Amp

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Simple Class-D Amp

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Pulse Width Modulation

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Commercial Class-D Amp Specifications VS Sublimity Audio Class-D Amp

Specification Alpine MRP-M450Value

Sublimity AudioValue

Power Requirements 14.4V DC (11V to 16V) 12V DC (10V to 14V)

Efficiency 80 % 80 %

RMS Power Per channel into 4 ohms: 220W x 1 (1% THD) At 12V: 100W TotalPer Right/Left Channel into 4 ohms: 15WSubwoofer Channel into 4 ohms: 60W

Channels 1 Channel (Mono) Operation 2 Right/Left Channels1 Subwoofer Channel

Frequency Response 20Hz - 200Hz (+3/-3dB) Right/Left Channel: 175Hz – 20kHzSubwoofer Channel: 20Hz – 200Hz

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Getting Started

• Researched amp design

• Broke the project down into individual groups

• Each member focused on specific part

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Building and Testing

• Built each unit independently

• Each unit was tested/debugged until successful

• Individual units were integrated together to build full amp design

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Block Diagram

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Schematic Diagram

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A Single Channel

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Preamplifier/Filter

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Output Filters

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Frequency Response

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Results

Planned Measured

Frequency Response

Satellites: 200Hz-30kHz

Sub: 0Hz-200Hz`

Satellites: 196Hz-42.3kHz

Sub: ~20Hz-188Hz

Voltage Gain Satellites: 12V/V

Sub: 24V/V

Satellites: 15V/V

Sub: 35V/V

Power Gain Satellites: 12W

Sub: 60W

Satellites: 14.1W

Sub: 76.6W

Efficiency >80% 92%

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Wrap It Up

• Class-D amps are way more efficient

• EMI on a breadboard is a nightmare

• Future release would be surface mounted

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Crank the Tunes!

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Thanks for listeningAny questions?

Great appreciation is given to the following sponsors:

Mundorf provided the output filter components. Visit them at www.mundorf.com

International Rectifier provided the gate driver and MOSFET components.  Visit them at www.irf.com

Texas Instruments provided the PWM controller. Visit them at www.ti.com

Linear Technology provided the simulation software necessary to test the design: LTSpice/SwCad III

Download your free copy at www.linear.com