Audio Amplifier Supply Voltage Control for Battery Playback Efficiency
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Solution Overview
Problem
Existing battery-powered playback devices face challenges in achieving high sound volumes while maintaining long runtime on battery power, as conventional designs use fixed supply voltages that are often higher than necessary, leading to inefficient power consumption.
Innovation Solution
Implementing a power supply with high efficiency and low bandwidth to generate a varying amplifier supply voltage using a feedforward control loop based on future audio data, anticipating voltage requirements to avoid rapid changes and prevent distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a fixed high supply voltage is used for the amplifier, then the device can deliver high sound volumes, but power consumption increases and battery runtime decreases
Solution Approach 1:
The patent implements dynamic supply voltage adjustment where the amplifier supply voltage varies over time based on the instantaneous audio signal requirements. The power supply transitions from a fixed voltage architecture to a dynamic one that adapts to the audio content, delivering high voltage only when needed for peak sound output and reducing voltage during low-demand periods to conserve battery power.
Solution Approach 2:
The patent changes the voltage parameter from a fixed value to a time-varying parameter that tracks the envelope of the audio signal. By modulating the supply voltage parameter in accordance with the audio content's instantaneous power requirements, the system optimizes the trade-off between sound volume capability and power consumption, directly addressing the technical contradiction.
2Use of energy by moving object
If the amplifier supply voltage is reduced to improve power efficiency, then battery runtime increases, but audio quality and sound volume may be compromised
Solution Approach 1:
The patent employs a feedforward control mechanism where the power supply anticipates upcoming voltage requirements by analyzing future audio data in advance. This preliminary action allows the supply voltage to be adjusted proactively before the audio signal demands it, preventing distortion and maintaining audio quality while optimizing power efficiency. The system prepares the voltage in advance rather than reacting after distortion occurs.
Solution Approach 2:
The patent implements a control system that monitors audio signal characteristics and adjusts the amplifier supply voltage accordingly. By incorporating feedback from the audio signal analysis, the system ensures that voltage reductions do not compromise audio quality, as the feedback mechanism detects when voltage adjustments might affect sound fidelity and compensates accordingly.
3Use of energy by moving object
If the amplifier supply voltage changes rapidly to follow audio signal demands, then power efficiency improves, but distortion occurs due to bandwidth limitations
Solution Approach 1:
The feedforward control architecture allows the power supply to anticipate and prepare for upcoming voltage demands by analyzing future audio data. This preliminary action eliminates the need for rapid reactive voltage changes that would exceed the power supply's bandwidth capabilities, thereby preventing distortion while maintaining power efficiency benefits.
Solution Approach 2:
The system takes preliminary anti-action by pre-adjusting the supply voltage before the audio signal demands it, based on predicted future requirements. This prevents the harmful effect of voltage lag and distortion that would occur if the system waited for the audio signal to demand voltage changes, thus counteracting potential distortion before it can occur.
Data Source
AI summary
A playback device including a processor that executes program instructions such that the playback device is configured to receive first audio data representing audio content, generate and output second audio data based on the first audio data, and at least in part while generating and outputting the second audio data, generate and output a control signal associated with the second audio data to vary a supply voltage for an audio amplifier. The playback device also includes a switch-mode power supply (SMPS) that varies the supply voltage for the audio amplifier based on the control signal. The playback device also includes an amplifier circuitry comprising the audio amplifier powered by the supply voltage from the SMPS. The amplifier circuitry is configured to receive the second audio data and generate an analog audio signal to drive a speaker based on the second audio data.