Audio Amplifier Gain Control Using Model-Based Current Estimation
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Solution Overview
Problem
Audio amplifiers in mobile applications, such as automobiles, face high power consumption issues due to nominal supply voltage, leading to increased weight and fuel consumption from thick supply lines, and require strict current limits that vary with user settings and audio signals, necessitating a solution to monitor and control current consumption.
Innovation Solution
An audio amplifier with a variable gain amplifier and a limiter gain calculation unit that estimates input or output current based on a mathematical model, adjusting the limiter gain to prevent exceeding a threshold current value, thereby controlling input or output current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the supply voltage is increased to reduce current consumption, then the input current consumption decreases, but the supply line cross section and vehicle weight increase
Solution Approach 1:
The patent applies dynamics by implementing a dynamic current limiter that continuously monitors and adjusts the amplifier's output signal based on real-time current consumption measurements. The limiter adapts its limiting threshold and behavior according to the actual operating conditions, allowing the system to operate efficiently at nominal voltage without requiring oversized supply lines or increased vehicle weight.
2Reliability
If strict maximum current limits are imposed to prevent overheating, then supply line safety is improved, but the amplifier's output capability and audio quality are restricted
Solution Approach 1:
The patent implements feedback by measuring the actual current consumption of the amplifier and using this information to dynamically adjust the limiting behavior. The current limiter continuously monitors the amplifier's output current and compares it against dynamically determined thresholds, providing feedback control that ensures supply line safety while maximizing the amplifier's output capability within safe operating limits.
Solution Approach 2:
The patent applies parameter changes by dynamically modifying the limiting threshold and limiter gain based on measured current consumption and operating conditions. Rather than using fixed conservative limits, the system adjusts parameters in real-time to allow higher output capability when conditions permit, thereby maintaining supply line safety while improving amplifier productivity.
3Use of energy by moving object
If current limiting is implemented to control power consumption, then power supply requirements are reduced, but the device complexity increases
Solution Approach 1:
The patent applies self-service by implementing a current limiter that automatically monitors its own current consumption and autonomously adjusts its limiting behavior without requiring external control systems. The amplifier measures its own output current, compares it against thresholds, and dynamically adjusts the limiter gain accordingly, enabling self-regulated power consumption control while minimizing additional device complexity.
4Use of energy by moving object
If dynamic current monitoring and control is implemented, then current consumption is optimized, but the measurement and control complexity increases
Solution Approach 1:
The patent applies merging by integrating the current measurement and limiting control functions directly into the amplifier's existing signal processing path. The current sensing, measurement, and limiting control are combined in a unified circuit architecture rather than being implemented as separate independent systems, thereby optimizing current consumption while minimizing the complexity of measurement and control infrastructure.
Data Source
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AI summary
An audio amplifier for amplifying an input audio signal so as to provide an amplified output signal is disclosed. The audio amplifier includes a variable gain amplifier receiving the input audio signal and providing the output signal, whereby the output signal corresponds to the input signal amplified by a limiter gain. The audio amplifier further includes a limiter gain calculation unit, thus the input signal is amplified by the limiter gain. A control unit receives a signal representative of the input signal and is configured to estimate, based on a mathematical model, the input current or the total output current of the audio amplifier thus providing an estimated current signal corresponding to (and resulting from) the output signal, whereby the limiter gain calculation unit is configured to calculate, dependent on the estimation, the limiter gain such that the actual input current or the total output current of the audio amplifier does not exceed a threshold current value.