Hearing Device Receiver Current Estimation
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Solution Overview
Problem
Existing hearing devices face challenges in estimating the receiver current without impacting the maximum power output, as methods like series resistor insertion affect the power output and impedance.
Innovation Solution
A hearing device with a receiver current estimation unit that includes a filter with frequency response dependent on the receiver impedance, using a digital-to-analog converter, averaging unit, and multiplier to estimate the receiver current based on the power amplifier supply voltage and audio signal characteristics, without adding series resistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a series resistor is inserted on the supply line to measure receiver current, then current measurement becomes possible, but the maximum power output of the hearing device is impacted and overall impedance increases
Solution Approach 1:
The patent uses an intermediary approach by measuring the voltage across the power amplifier output terminals instead of inserting a series resistor in the supply line. This voltage measurement, combined with knowledge of the power amplifier's output impedance, allows indirect calculation of receiver current without physically disrupting the power supply path. The intermediary measurement point (voltage across PA output) enables current estimation while preserving the original power delivery path intact.
Solution Approach 2:
The patent replaces the physical mechanical/electrical intervention of inserting a series resistor with a signal processing approach. Instead of modifying the power delivery path physically, the invention uses digital signal processing to estimate current based on voltage measurements and modeled relationships. This substitution of physical measurement with computational estimation eliminates the harmful impact on power output while achieving the measurement goal.
2Measurement precision
If a series resistor is inserted in the power amplifier branches to measure current, then receiver current can be determined, but the overall impedance increases and power output is reduced
Solution Approach 1:
The patent extracts the measurement function from the power delivery path itself. Instead of embedding measurement resistors within the power amplifier branches, the invention separates the measurement function by using voltage sensing at the output terminals combined with computational current estimation. This extraction removes the measurement elements from the power path, preventing any increase in overall impedance while maintaining measurement capability.
Solution Approach 2:
The patent creates a computational model that copies the electrical relationships of the power amplifier and receiver system. By modeling the output impedance characteristics and using voltage measurements through this model, the system can estimate current without physical current-sensing resistors. This virtual copying of electrical behavior enables measurement without physical intervention that would alter impedance.
Data Source
Figure 1~2
AI summary
A hearing device is provided with means for estimating the current consumed by its receiver. The hearing device comprises a signal input means for converting an input signal into a digital audio signal, a signal processing unit for processing the digital audio signal, a digital-to- analog converter for converting a processed audio signal from the signal processing unit, a power amplifier for amplifying a converted audio signal from the digital-to-analog converter, a receiver for generating sound according to an amplified audio signal from the power amplifier, and a battery for powering the hearing device. Furthermore, the inventive hearing device additionally comprises a receiver current estimation unit comprising a filter for filtering a receiver current indicative signal derived from the processed audio signal, the filter having a frequency response H(f) which is dependent on an impedance Z(f) of the receiver.