Digital Amplifier Error Correction for Supply Voltage Fluctuations
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Solution Overview
Problem
Digital amplifiers, particularly class D amplifiers, face challenges in correcting signal distortions caused by non-ideal switching transistors and supply voltage fluctuations, leading to output signal disturbances, especially in mobile devices where voltage fluctuations are significant.
Innovation Solution
A digital amplifier with an analogue error correction circuit that converts digital input signals into amplitude-discrete and temporally analogue signals, modulates pulse widths based on an analogue error signal, and uses a power switching stage with an analogue feedback circuit to generate an error signal for adjusting the correction, thereby compensating for supply voltage fluctuations and improving signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If digital amplifiers use switching transistors for high efficiency, then power loss is reduced, but signal distortions and output signal disturbances occur due to non-ideal switching characteristics
Solution Approach 1:
The patent implements an analogue feedback circuit that feeds back a portion of the output signal to the input stage. This feedback mechanism detects signal distortions caused by non-ideal switching transistors and automatically adjusts the input signal to compensate for these distortions, thereby maintaining high signal quality while preserving the energy efficiency of switching transistors.
Solution Approach 2:
The patent introduces an intermediate analogue error correction circuit between the digital input stage and the switching transistor stage. This intermediary circuit converts digital error signals into analogue correction signals that can be applied to the switching stage, enabling precise compensation for switching non-idealities without requiring high-resolution analogue/digital converters.
2Reliability
If high-resolution analogue/digital converters are used to correct signal distortions, then signal quality improves, but device complexity and cost increase
Solution Approach 1:
The patent applies partial correction by using a low-resolution analogue/digital converter (e.g., 1-bit or 1.5-bit) that provides just enough correction capability to handle the most significant distortions. This partial correction approach achieves adequate signal quality improvement without the complexity and cost of high-resolution converters, recognizing that perfect correction is unnecessary for practical applications.
3Ease of operation
If mobile devices operate with battery power, then portability improves, but supply voltage fluctuations increase causing amplifier performance degradation
Solution Approach 1:
The feedback circuit monitors output signal quality and automatically adjusts operating parameters to compensate for supply voltage fluctuations. When battery voltage varies during operation, the feedback mechanism detects resulting distortions and modifies the amplification process accordingly, maintaining consistent performance despite portable power supply variations.
Data Source
AI summary
Digital amplifier for amplifying a digital input signal, comprising a digital modulator for converting the digital input signal into an amplitude-discrete and temporally analogue signal, comprising an analogue error correction circuit which modulates the pulse widths of the amplitude-discrete and temporally analogue signal in dependence on an analogue error signal, comprising a power switching stage, the input of which receives the signal modulated by the error correction circuit and which delivers the modulated signal amplified at an output and comprising an analogue feedback circuit which, in dependence on the output signal of the digital modulator and on the output signal of the power switching stage, generates the analogue error signal for adjusting the analogue error correction circuit.