H-Bridge Output Mode Switching for Hearing Aid Radio Interference
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Solution Overview
Problem
Digital hearing aids face interference issues due to capacitive coupling from three-level output stages, which affect radio receiver performance and limit their range and reliability, especially when used with wireless remote controls and other electronic components.
Innovation Solution
A method is introduced to dynamically switch between two-level and three-level modes for the H-bridge output converter based on the operating mode of the radio receiver, reducing interference by using a sigma-delta modulator to generate bit streams with two or three discrete levels and a controller to select the appropriate mode, thereby minimizing power consumption and capacitive interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a three-level H-bridge output stage is used to drive the acoustic output transducer, then power efficiency is improved and output performance is enhanced, but capacitive interference is generated that affects radio receiver performance
Solution Approach 1:
The patent implements dynamic switching between two-level and three-level H-bridge output modes based on the operational state of the radio receiver. The controller monitors whether the radio receiver is in idle mode or actively receiving signals, and accordingly selects the appropriate output mode. When the radio receiver is actively receiving, the system switches to two-level mode to minimize capacitive interference; when idle, it switches to three-level mode to maximize power efficiency and output performance.
Solution Approach 2:
The patent changes the operational parameters of the H-bridge output stage by switching between two discrete configurations: two-level mode with reduced voltage swings for low interference, and three-level mode with optimized voltage utilization for high efficiency. This parameter switching allows the system to adapt to different operational requirements and eliminate the need for separate dedicated output stages for different functions.
2Loss of energy
If the H-bridge output stage operates in three-level mode continuously, then power consumption is minimized, but interference with radio signal reception increases
Solution Approach 1:
The patent employs periodic monitoring of the radio receiver's operational state and periodic switching between two-level and three-level H-bridge modes. The controller continuously or periodically checks whether the radio receiver is in idle mode or actively receiving signals, and switches the output mode accordingly. This periodic adaptation ensures that power consumption is minimized during idle periods while radio signal reception reliability is maintained during active reception periods.
Solution Approach 2:
The patent implements a feedback mechanism where the controller monitors the operational state of the radio receiver and uses this information to control the H-bridge output mode. The radio receiver's state (idle or receiving) serves as feedback that determines the appropriate output configuration. This closed-loop control ensures that the system automatically adjusts to maintain both power efficiency and reception reliability without user intervention.
3Reliability
If a two-level H-bridge output stage is used to reduce interference, then radio receiver performance is improved, but power efficiency and output performance deteriorate
Solution Approach 1:
The patent makes the H-bridge output stage dynamic by enabling switching between two-level and three-level operational modes. Rather than being fixed in one configuration, the system adapts its output characteristics based on real-time requirements. The controller dynamically selects the appropriate mode: two-level when radio performance is critical, three-level when power efficiency is paramount, thereby eliminating the need to choose one compromised configuration.
Solution Approach 2:
The patent creates a universal H-bridge output stage that can perform multiple functions by operating in different modes. The same hardware circuitry serves both as a low-interference two-level output stage for radio reception applications and as a high-efficiency three-level output stage for audio output applications. This multi-functionality eliminates the need for separate dedicated circuits and optimizes performance for both functions.
Data Source
AI summary
In a hearing aid (40), a direct-digital H-bridge output driver stage (1) driven by a sigma-delta modulator (2) is configured to operate in a power-saving three-level output mode or a power-consuming two-level output mode. The three-level output mode of the H-bridge output driver stage (1) has low power consumption but suffers the disadvantage of emitting capacitive noise potentially interfering with the reception of radio signals in a radio receiver (17) in the hearing aid (40). By providing a novel method of selecting the two-level output mode whenever the radio receiver (17) is receiving signals, and selecting the three-level output mode whenever the radio receiver (17) is idle, this capacitive interference does not disturb the radio receiver (17) in the hearing aid (40). The invention provides a method and a hearing aid.