Differential Class-D Amplifier Switching for Lower EMI and Power Loss
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Solution Overview
Problem
Conventional Class-D power amplifiers using differential pulse width modulation increase energy consumption and generate high-frequency noise due to the need for two output signals, which can cause electromagnetic interference and inefficiencies in loudspeaker cables.
Innovation Solution
A Class-D amplifier circuit with a differential pulse width modulator that includes a comparator to switch both output signals from a high to a low state when both are in a high state, reducing the number of switching transitions and maintaining the encoded differential pulse modulated signal, thereby reducing energy consumption and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If differential pulse width modulation is used to represent input signal with two modulated output signals, then interference cancellation is improved, but energy consumption increases
Solution Approach 1:
The patent extracts and eliminates redundant switching transitions by detecting when both differential output signals are in the same state (both high or both low) and removing the corresponding switching event. This extraction of unnecessary switching operations reduces energy consumption while preserving the interference cancellation benefit of differential modulation.
Solution Approach 2:
The patent discards redundant switching transitions that do not contribute to signal transmission. By identifying and eliminating these redundant transitions where both signals switch simultaneously, the system recovers energy that would otherwise be wasted, while maintaining the integrity of the differential pulse width modulated signal.
2Reliability
If two output signals are generated for differential amplification, then interference cancellation is improved, but high-frequency noise increases
Solution Approach 1:
The patent extracts and removes redundant switching transitions from the differential output signals. By detecting when both signals transition simultaneously and eliminating these redundant transitions, the system reduces high-frequency noise components while preserving the differential signal structure that provides interference cancellation.
3Use of energy by moving object
If switching transitions are reduced in differential output signals, then energy consumption is reduced, but signal transmission may be affected
Solution Approach 1:
The patent employs feedback mechanisms through logic circuits that monitor the states of both differential output signals. By detecting when both signals are in the same state, the system intelligently determines which switching transitions are redundant and can be safely eliminated without affecting signal transmission integrity, thus reducing energy consumption.
Solution Approach 2:
The patent introduces intermediary logic circuits and control mechanisms that mediate between the differential pulse width modulator and the output stage. These intermediaries detect redundant transitions and control the switching operations, ensuring that energy-saving measures do not compromise signal transmission fidelity.
Data Source
AI summary
A power amplifier is disclosed. In one embodiment, the power amplifier is a Class-D Amplifier having a differential pulse width modulator is disclosed. The differential pulse width modulator has an input for receiving an input signal, a first output for outputting a first signal and a second output for outputting a second signal. A difference between the first signal and the second signal represents the pulse modulated signal. The differential pulse width modulator further has a comparator for comparing the first and second output signals. The comparator switches both the first and second output signal from a high state to a low state, if both the first and second output signals are in a high state.