Class-G Audio Amplifier With Buck Control and Settling Delay
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Solution Overview
Problem
Conventional class-AB audio amplifiers have high power consumption, especially during light loads, due to their inefficiencies in voltage regulation and signal processing, leading to potential distortion and increased electromagnetic interference.
Innovation Solution
An audio amplifier with an embedded buck controller operating in a class-G configuration, which includes a buck converter that dynamically adjusts output voltage based on detected peak amplitudes and introduces a delay in signal processing to ensure settling time, reducing power consumption and preventing distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional class-AB amplifiers are used, then audio signal amplification is achieved, but power consumption is high especially during light loads
Solution Approach 1:
The patent implements dynamic supply voltage switching by monitoring the audio signal amplitude and switching between different supply voltage levels (e.g., 5V, 3.3V, 1.8V) based on the signal strength. During light loads, the amplifier operates at lower voltage levels to reduce power consumption, while during heavy loads, it switches to higher voltage levels to maintain signal quality and prevent distortion.
Solution Approach 2:
The patent changes the supply voltage parameter dynamically based on the audio signal amplitude. By adjusting the supply voltage according to the signal level, the amplifier achieves optimal power efficiency while maintaining adequate headroom for the signal, thus resolving the contradiction between low power consumption and high signal quality.
2Use of energy by moving object
If dynamic voltage adjustment is implemented, then power consumption is reduced, but voltage settling time causes signal delay
Solution Approach 1:
The patent anticipates the need for voltage switching by monitoring the audio signal amplitude in advance. When a signal level change is detected, the supply voltage is switched proactively before the actual signal processing begins, allowing the voltage to settle during the delay period and minimizing the impact on the audio output.
Solution Approach 2:
The patent introduces a delay circuit as an intermediary element that compensates for the voltage settling time. This delay circuit holds the audio signal temporarily during the voltage transition period, ensuring that the signal is not distorted or clipped while the supply voltage settles to its new level.
3Reliability
If sufficient headroom is maintained to prevent distortion, then signal quality is preserved, but power consumption increases
Solution Approach 1:
The patent applies partial headroom by providing sufficient voltage margin only when the audio signal amplitude requires it. During low-level signals, the amplifier operates with minimal headroom to reduce power consumption, while during high-level signals, adequate headroom is provided to prevent clipping and distortion. This selective application of headroom resolves the contradiction between signal quality and power consumption.
4Reliability
If class-AB operation is used, then continuous signal amplification is achieved, but quiescent current is high
Solution Approach 1:
The patent implements periodic voltage level adjustments based on the audio signal characteristics. Instead of maintaining a constant high quiescent current as in traditional class-AB amplifiers, the supply voltage is periodically adjusted to match the signal demands, allowing the amplifier to enter lower power states during periods of low or no signal activity while maintaining readiness for signal amplification.
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
The solution significantly reduces power consumption by up to 50% during average listening conditions compared to conventional class-AB amplifiers, while maintaining audio quality by ensuring sufficient headroom and avoiding voltage clamping.
Implementation Method 1
a buck controller having a supply input configured to receive a battery voltage, the buck controller configured to control an output voltage at the first supply terminal
Implementation Method 2
a delay insertion circuit configured to receive a processed digital stream from the digital signal processing circuit and configured to provide the processed digital stream to the class-AB driver stage a delay time after receiving the processed digital stream, where the delay time is based on the settling time
Data Source
AI summary
An audio amplifier includes: a buck controller configured to control an output voltage at a first supply terminal, the output voltage selected from a set including a plurality of output voltages, where the output voltage takes a settling time to settle; a first audio bridge including: a class-AB driver stage coupled to the first supply terminal, and a delay insertion circuit configured to receive a processed digital stream and provide the processed digital stream to the class-AB driver stage a delay time after receiving the processed digital stream, where the delay time is based on the settling time; and an audio amplitude detector configured to detect a first peak amplitude in the first digital audio stream, where the buck controller is configured to select a lowest output voltage from the set that is higher than the first peak amplitude plus a headroom voltage.