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Hardware/Electronics DevelopmentAudioAmplifier DesignElectronics

UA2-125 Amplifier

High-fidelity Class-D amplifier design with integrated DSP, thermal management, and production-ready validation

Project Media

UA2-125 Amplifier image 1
UA2-125 Amplifier image 2

My Contributions

  • Led complete amplifier schematic design and component selection
  • Designed 4-layer PCB with optimized EMI layout and thermal management
  • Developed DSP firmware for speaker protection and EQ algorithms
  • Built automated test fixtures using APx555 audio analyzer
  • Created production test procedures with pass/fail acceptance criteria
  • Coordinated thermal validation testing across temperature range
  • Authored technical documentation for manufacturing handoff

Problem

Consumer audio products demand high-performance amplification in compact form factors. The UA2-125 project required developing a Class-D amplifier capable of delivering 125W with low distortion, efficient thermal management, and a design suitable for manufacturing at scale.

Approach

The UA2-125 is a high-fidelity Class-D amplifier designed for integration into powered speakers and audio systems.

Key Design Goals:

  • 125W continuous power output with THD+N < 0.05%
  • Integrated DSP for speaker protection and EQ
  • Efficient thermal design without requiring active cooling in typical use cases
  • Design for manufacturability (DFM) from day one

What I Built

Amplifier Stage:

  • Class-D topology with high-efficiency switching
  • Careful PCB layout for EMI minimization
  • LC output filter optimized for audio band performance

DSP Integration:

  • Multi-band EQ and dynamic range control
  • Speaker protection (thermal, excursion limiting)
  • Configurable via I2C for product customization

Thermal Management:

  • Simulation-driven heatsink design
  • Thermal shutdown protection with graceful recovery
  • Validated across operating temperature range (-10C to +50C)

Validation & Test:

  • Full electrical characterization (frequency response, THD, IMD, SNR)
  • Thermal imaging and stress testing
  • EMC pre-compliance testing
  • Production test procedure development

Outcomes

Performance Achieved:

  • 125W @ 4 ohms, THD+N < 0.03% at 1W
  • Efficiency > 90% at rated power
  • SNR > 110dB (A-weighted)

Manufacturing Readiness:

  • Complete BOM with dual-source components
  • Test procedure and acceptance criteria documented
  • First article inspection passed

What's Next

  • Integration into next-generation powered speaker product
  • Explore higher power variants (250W, 500W)
  • Evaluate GaN switching for improved efficiency
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