Class D Audio Amplifier with Feedback after LC

Class D audio amplifiers are widely used in mobile phones, cars and home stereo systems. To comply with EMI (electromagnetic interference) regulation, a bulky LC filter is often required to filter the output signal of a class D amplifier.

Such LC filter can be very nonlinear, and therefore, incorporating it in a feedback loop is desired to optimal system performance. However, this poses great challenges to the system stability, because LC filter cut-off frequency has tolerance, and can move due to component aging.

• A prior art can tolerate +/-30% LC spread, but may not be enough
• Limitations exist on both lower bound and higher bound

Project goals

• Comprehensive literature study to compare different digital input class D architectures.
• Propose a digital input class D amplifier topology that has the potential to advance state-of-the-art.
• This project will aim for a tape-out in TSMC 180nm BCD around May 2022.

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Last modified: 2021-12-01