Multi-Bit Δ-Σ Digital Speaker Architecture Without Analog LC Filters
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Solution Overview
Problem
Current digital loudspeaker systems face limitations in achieving low power consumption, small form factor, and complete digitalization due to reliance on analog LC filters, which restricts the integration level and noise suppression capabilities, and are prone to nonlinear distortions and high power consumption.
Innovation Solution
A multi-bit Δ-Σ modulation-based digital speaker system that employs oversampling interpolation filtering, thermometer coding, multichannel mismatch shaping, and coding format conversion to convert high bit-width PCM signals into low bit-width signals, enabling self-demodulating and self-filtering capabilities without traditional analog filters, and optimizing power consumption and noise suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional analog LC filters are used for digital-to-analog conversion, then the speaker unit can be driven in analog input state, but the system suffers from high power consumption, large volume, and limited integration level
Solution Approach 1:
The patent extracts and removes the analog LC filter from the system by implementing complete digitalization of the speaker unit. The digital speaker unit directly processes digital input signals without requiring analog-to-digital conversion or analog filtering stages, thereby eliminating the power-consuming analog filter component while maintaining system reliability through digital signal processing.
Solution Approach 2:
The patent replaces the mechanical/analog filter system with a digital signal processing system. Instead of using physical inductors and capacitors to filter signals, the invention uses digital algorithms and processing to achieve the same filtering and conversion functions, thereby reducing power consumption and enabling better integration.
2Reliability
If analog LC filters are used for digital-to-analog conversion, then the speaker unit can be driven, but the system volume and weight increase
Solution Approach 1:
The patent extracts and removes the heavy analog LC filter components from the system. By implementing a fully digital speaker unit that processes digital signals directly, the invention eliminates the need for physical inductors and capacitors, thereby significantly reducing system weight while maintaining the essential digital-to-analog conversion capability through digital signal processing.
Solution Approach 2:
The patent replaces the mechanical filter system with a digital processing system. Instead of using physical components that add weight, the invention uses digital algorithms to perform filtering and conversion functions, thereby achieving the same technical效果 with minimal weight increase.
3Device complexity
If current digital power amplifier chips without analog low-pass LC filters are used, then integration level improves, but noise and harmonic distortion suppression ability is limited
Solution Approach 1:
The patent implements a feedback mechanism in the digital speaker unit where the output signal is monitored and fed back to the input stage. This feedback loop enables real-time correction of noise and harmonic distortion components, allowing the system to maintain high integration level without compromising suppression ability. The feedback control dynamically adjusts signal processing to minimize harmful factors.
Solution Approach 2:
The patent introduces an intermediary digital signal processing stage between the power amplifier and speaker unit. This intermediary processing layer performs noise filtering and harmonic distortion correction using digital algorithms, thereby maintaining system integration while effectively suppressing harmful factors that would otherwise be handled by analog filters.
4Reliability
If analog LC filters are used for digital-to-analog conversion, then the speaker unit can be driven, but the electro-acoustic conversion efficiency is low
Solution Approach 1:
The patent extracts and removes the analog LC filter that causes energy loss in the conversion process. By implementing a fully digital speaker unit that processes digital signals directly, the invention eliminates the inefficient analog filtering stage and achieves higher electro-acoustic conversion efficiency through optimized digital signal processing and direct digital-to-acoustic conversion.
Solution Approach 2:
The patent replaces the inefficient mechanical/analog filter system with a digital processing system. Instead of using physical components that cause energy loss during analog conversion, the invention uses digital algorithms to perform the same functions with minimal energy loss, thereby significantly improving electro-acoustic conversion efficiency.
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 achieves improved sound quality with reduced harmonic distortion, lower power consumption, and increased integration density, suitable for portable devices, while eliminating the need for digital-to-analog conversion, thus enhancing fidelity and battery life.
Implementation Method 1
multiple speaker units in a speaker array or multiple voice coils in a multiple voice coil speaker cooperate to complete an electro-acoustic conversion, so as to convert a digital switch electrical signal into an analog sound signal
Data Source
AI summary
The present invention discloses an implementation method and a device of a multi-bit Δ-Σ modulation-based digital speaker system. The method comprises, 1) digital format converting; 2) oversampling interpolation filtering; 3) multi-bit Δ-Σ modulating; 4) thermometer coding; 5) multi-channel mismatch shaping; 6) coding format converting; 7) multi-channel digital power-amplifying; 8) driving a speaker array or a multiple voice coil speaker to sound. The device comprises: a digital input interface, an oversampling interpolation filter, a multi-bit Δ-Σ modulator, a thermometer coder, a multi-channel mismatch shaper, a coding format converter, a multi-channel digital power-amplifier, and a speaker array or a multiple voice coil speaker; each portion being connected in proper order. The present invention can achieve a high-power output under a low-voltage power supply, save power consumption, implement a single-chip integration of a multi-channel reproducing system, reduce the volume and weight of the system and the implementing cost, and improve the quality of the reproduced sound.