Modal Amplifier Rail Modulation for Fidelity and Power Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing linear amplifiers, such as class A amplifiers, are inefficient, especially at low signal levels, while switching amplifiers like class D amplifiers offer high efficiency but lower fidelity.
Innovation Solution
The power supply rails of a linear amplifier are modulated by a switching amplifier, allowing the linear amplifier to operate efficiently even at low signal levels while maintaining high fidelity by tracking the input signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a linear amplifier (class A) is used to amplify audio signals, then high fidelity sound reproduction is achieved, but power efficiency deteriorates especially at low signal levels
Solution Approach 1:
The power supply rail voltage is dynamically modulated to track the instantaneous amplitude of the audio signal. When the signal level is low, the rail voltage is reduced accordingly, allowing the linear amplifier to maintain high fidelity operation only when necessary and reducing power consumption during low-signal periods. This dynamic adaptation resolves the contradiction between maintaining fidelity and improving power efficiency.
Solution Approach 2:
The invention changes the operating parameters of the linear amplifier by modulating the power supply rail voltage based on the signal amplitude. By varying the rail voltage parameter in response to signal levels, the system achieves both high fidelity at appropriate voltage levels and improved power efficiency at lower voltage levels, resolving the trade-off between these two parameters.
2Use of energy by moving object
If a switching amplifier (class D) is used to improve power efficiency, then power efficiency is improved, but fidelity of sound reproduction deteriorates
Solution Approach 1:
The invention introduces a modulator circuit as an intermediary between the audio signal source and the linear amplifier. This modulator dynamically adjusts the power supply rail voltage based on the signal amplitude, enabling the linear amplifier to operate efficiently at lower voltages during low-signal periods while maintaining the ability to deliver high fidelity when needed. The modulator acts as a mediator that reconciles the efficiency benefits with fidelity requirements.
3Use of energy by moving object
If the power supply rail voltage is modulated to track the audio signal amplitude, then power efficiency is improved at low signal levels, but system complexity increases
Solution Approach 1:
The modulator circuit serves multiple functions: it monitors the audio signal amplitude, generates the appropriate control voltage, and adjusts the power supply rail voltage accordingly. By consolidating these functions into a single multi-functional circuit, the invention reduces the overall system complexity that would otherwise result from separate components for each function, while still achieving the power efficiency benefits of rail voltage modulation.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Configurable amplifier systems are described in which the power supply rail of a linear amplifier, e.g., a class A amplifier, is modulated by a switching amplifier, e.g., a class D amplifier, that may also be configured to operate independently of the linear amplifier. Techniques are also described by which the standing current of the output stage of a linear amplifier is modulated based on the input signal to the linear amplifier or based on modulation of the power supply rail of the linear amplifier.