Class-D Garage Band Amplifier

Team: Aaron Danielson, Robert Mann,Randall Newcomb, Scott RussellSponsor: Nigel Thompson

OverviewThe Purpose of the Class-D Garage Band AmplifierRequirements and Stretch GoalsSystem ConceptSystem Block DiagramSampling and Bitrate ConstraintsTask BreakdownBudgetProject Schedule

Purpose

1. Class D Amplifier Power Efficiency

2. Price Point 3. Open Source4. Customizability

Requirements

• An amplifier output will be driven by an FPGA• The output stage will be a PWM H-bridge

amplifier • High quality audio• Low cost• High efficiency• Analog Input

• Output of more than 100W• 4-Layer PCB • …

Stretch Goals

• An enclosure will be constructed to house the amplifier, FPGA and speaker• An alternate amplifier will be implemented• Digital Input

PWM Analog InDigital In

PSU PSU

Stretch Goal

Required

System Concept

Images from Google Image

Pre-Filter

System Block Diagram - FPGA

System Block Diagram - Output

Description of Major Tasks• Design a Top Level Testbench

• Contains all the modules for testing that will be synthesized onto the FPGA.

• Instantiate Pacoblaze uP and write necessary assembly in test environment to reduce synthesize time later.

• Digital Signal Processor• Design 2 filters – one each for bass & treble.• Interface with state machine to allow user to adjust settings.

• Hardware State Machine• Implement a menu system to control all the systems.• Integrate the uP communication with the state machine for user

feedback through the LCD and buttons

• Amplifier • Produce a breakout board for inintial testing• Layout custom PCB • Implement final design and test the output stage

• Speaker Enclosure• Build the enclosure• Design bandpass filters for the selected speaker

Bitrate & Sample Rate Comparison – CD Quality

Bitrate & Sample Rate Comparison – Low Sample

Rate

Bitrate & Sample Rate Comparison – Low Bit Depth

Bitrate & Sample Rate Comparison – A Good

Compromise

Budget

Budget

Project Schedule

Conclusion