Multi-Channel Amplifier Phase Shifting for Lower EMI
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Solution Overview
Problem
Conventional amplification systems, such as those using Class-D amplifiers, face challenges in efficiently processing multiple input signals due to phase alignment issues and high switching frequencies, leading to electromagnetic interference and reduced audio signal quality.
Innovation Solution
The implementation of multiple channels with phase-shifted ramp signals, where each channel processes input signals with a unique ramp signal phase, and the use of periodic or pseudo-random jittering in the oscillation frequency to improve signal processing and reduce electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multiple channels share a common ramp signal, then device complexity is reduced, but phase alignment issues occur leading to reduced audio signal quality
Solution Approach 1:
The patent divides the single common ramp signal into multiple phase-shifted ramp signals for different channels. Each channel receives a ramp signal with a specific phase offset (e.g., 0°, 120°, 240° for three channels), which segments the original signal distribution problem and enables proper phase alignment in multi-channel audio amplification without requiring a completely separate ramp signal generation system for each channel.
2Productivity
If high switching frequencies are used, then amplification efficiency is improved, but electromagnetic interference increases
Solution Approach 1:
The patent converts the harmful electromagnetic interference generated by high-frequency switching into a beneficial effect by using phase-shifted ramp signals. The phase shifts cause the switching events of different channels to be distributed in time, transforming the concentrated EMI problem into a distributed pattern that can be more easily filtered and managed, while maintaining the high switching frequency benefits for amplification efficiency.
3Manufacturing precision
If phase-aligned ramp signals are used, then audio signal quality is improved, but electromagnetic interference increases
Solution Approach 1:
The patent implements periodic phase-shifting of ramp signals across multiple channels, where each channel operates with a systematically offset phase angle. This periodic distribution of switching events in time maintains the phase alignment necessary for high-quality audio reproduction while spreading out the electromagnetic interference occurrences, preventing simultaneous switching that would generate excessive EMI.
Data Source
AI summary
Systems and methods are provided for amplifying multiple input signals to generate multiple output signals. An example system includes a first channel, a second channel, and a third channel. The first channel is configured to receive one or more first input signals, process information associated with the one or more first input signals and a first ramp signal, and generate one or more first output signals. The second channel is configured to receive one or more second input signals, process information associated with the one or more second input signals and a second ramp signal, and generate one or more second output signals. The first ramp signal corresponds to a first phase. The second ramp signal corresponds to a second phase. The first phase and the second phase are different.