Loudspeaker Predistortion Circuit With Compression Gain Control
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Solution Overview
Problem
Existing non-linear distortion compensation circuits for loudspeakers, such as simplified feed-forward controllers, often result in predistortion signals being too large and getting cut off due to inaccuracies in linear amplitude modeling, and state feedback methods complicate operations.
Innovation Solution
Incorporating a gain module with a compression gain less than or equal to 1 into the compensation circuit to compress linear signals using a multiplier, ensuring the predistortion signal is not cut off, and utilizing a non-linear inverse dynamic circuit to accurately calculate and output the predistortion signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simplified feed-forward controller is used for non-linear distortion compensation, then the device complexity is reduced, but the predistortion signal becomes too large and gets cut off due to inaccuracies in linear amplitude modeling
Solution Approach 1:
The controller is segmented into distinct functional modules: a linear dynamic circuit for linear amplitude modeling, a gain module for compression gain calculation, a multiplier for signal compression, and a non-linear inverse dynamic circuit for predistortion signal generation. This segmentation allows each module to perform its specific function optimally while maintaining overall system manageability.
Solution Approach 2:
The gain module acts as an intermediary between the linear dynamic circuit and the non-linear inverse dynamic circuit. It introduces a compression gain (a positive number less than or equal to 1) that compresses the linear signal before it reaches the non-linear inverse dynamic circuit, preventing the predistortion signal from becoming too large and getting cut off.
2Reliability
If the compression gain is set to compress the linear signal, then the predistortion signal is prevented from being cut off, but the manufacturing precision of the compensation circuit increases
Solution Approach 1:
The compression gain is implemented as an adjustable parameter (a positive number less than or equal to 1) that can be optimized based on specific loudspeaker characteristics and operating conditions. This parameter adjustment allows the system to adapt to different scenarios without requiring complex circuit redesign, balancing reliability improvement with manufacturing feasibility.
3Measurement precision
If state feedback methods are used for non-linear distortion compensation, then the compensation accuracy is improved, but the ease of operation deteriorates due to complicated operations
Solution Approach 1:
The system performs preliminary linear amplitude modeling through the linear dynamic circuit and compression gain calculation through the gain module before the signal reaches the non-linear inverse dynamic circuit. This preliminary action prepares the signal in advance, eliminating the need for complex real-time state feedback operations during signal playback, thus maintaining accuracy while simplifying operation.
Data Source
AI summary
A non-linear distortion compensation circuit includes: a first input terminal of a linear dynamic circuit is configured to input an audio signal, and an output terminal is separately connected to a first input terminal of a gain module and a first input terminal of a multiplier; a second input terminal of the gain module is configured to input the audio signal, and an output terminal is connected to a second input terminal of the multiplier; an output terminal of the multiplier is connected to a first input terminal of a non-linear inverse dynamic circuit; a second input terminal of the non-linear inverse dynamic circuit is configured to input the loudspeaker model parameter, and an output terminal is connected to a loudspeaker. A compression gain that is output by the gain module is used to compress, by using the multiplier, a linear signal that is output by the linear dynamic circuit.