Switching Amplifier Bias Converter for Low-Power Audio Outputs
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Solution Overview
Problem
Existing audio amplifier systems for portable music systems with headphones require large, expensive capacitors for bias voltage or consume significant power with additional amplifiers, compromising power efficiency.
Innovation Solution
Implementing high efficiency converters, such as charge pumps or inductive converters, to provide the bias voltage at the common node of stereo transducers, reducing power consumption and BOM costs while maintaining audio fidelity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large capacitors are used to provide bias voltage at the common node, then the bias voltage can be maintained, but the system becomes expensive and occupies large space
Solution Approach 1:
The patent replaces the passive capacitor-based bias voltage generation with an active switching converter system. The mechanical/electrical energy storage function of large capacitors is substituted by a dynamic switching power conversion system that generates the required bias voltage through controlled energy transfer from the VCC supply, eliminating the need for large, expensive capacitors while maintaining voltage stability.
Solution Approach 2:
The invention changes the operating parameters of the bias voltage generation by transitioning from a static capacitor discharge model to a dynamic switching conversion model. The switching converter adjusts its duty cycle and switching frequency to maintain the bias voltage at the common node, allowing for compact implementation with small capacitors while preserving the required voltage level.
2Quantity of substance
If additional amplifiers are used to provide bias voltage, then the bias voltage can be generated with small capacitors, but power consumption increases significantly
Solution Approach 1:
The patent replaces the amplifier-based bias voltage generation with a switching converter system. The linear amplifier's continuous power dissipation is substituted by a switching converter that transfers energy efficiently through controlled switching actions, dramatically reducing power consumption while maintaining the ability to generate bias voltage with small capacitors.
Solution Approach 2:
The invention employs periodic switching action to generate the bias voltage. The switching converter operates in discrete switching cycles, transferring energy periodically to the common node to maintain the bias voltage. This periodic energy transfer is far more efficient than the continuous power dissipation of linear amplifiers, enabling small capacitor implementation with low power consumption.
3Use of energy by moving object
If Class G amplifiers are used to provide bias voltage, then power consumption is minimized, but the system complexity increases
Solution Approach 1:
The patent segments the bias voltage generation function from the audio amplification function. Instead of using Class G amplifiers which combine both functions in a complex multi-rail configuration, the invention separates them by dedicating a simple switching converter solely to bias voltage generation and separate Class AB amplifiers to audio amplification. This segmentation reduces overall system complexity while maintaining low power consumption.
Solution Approach 2:
The switching converter acts as an intermediary component that generates the bias voltage independently, which is then supplied to the common node and audio amplifiers. This intermediary approach simplifies the overall system architecture by eliminating the need for complex Class G amplifier configurations with multiple voltage rails, achieving low power consumption through a cleaner, more modular design.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Achieves power efficiency above 90% and reduces overall system power consumption and cost by using a single high efficiency converter for multiple audio channels, while minimizing artifacts like crosstalk and noise through feedback networks.
Implementation Method 1
Implementing high efficiency converters, such as charge pumps or inductive converters, to provide the bias voltage at the common node of stereo transducers
Implementation Method 2
Implementing high efficiency converters, such as charge pumps or inductive converters, to provide the bias voltage at the common node of stereo transducers
Data Source
AI summary
An audio amplifier system having improved power efficiency by wasting less power in its bias voltage circuit. An amplifier provides a voice signal to a first (+) input of a loudspeaker and a high efficiency converter provides a bias voltage to a second (−) input of the loudspeaker. In multi-loudspeaker systems, a single high efficiency converter can bias all the loudspeakers at a common node. The high efficiency converter can be a charge pump or a buck converter or the like, and has greater than 90% efficiency.