Delta-Sigma Hearing Aid Input Converter With Voltage Step-Up
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Solution Overview
Problem
Delta-sigma A/D converters in hearing aids face challenges in minimizing noise contribution from the amplifier while reducing current consumption, which affects battery life and noise sensitivity.
Innovation Solution
Implementing voltage transformers upstream and downstream of the amplifier in the delta-sigma A/D converter to increase the input and feedback signal voltages, thereby reducing the relative amplifier noise contribution and current demands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the bias current for the amplifier is reduced to decrease current consumption, then current consumption is reduced, but the noise figure of the amplifier increases
Solution Approach 1:
A voltage transformer is introduced as an intermediary component between the input signal and the amplifier. The transformer steps up the input voltage before it reaches the amplifier, allowing the amplifier to operate with lower bias current while maintaining adequate signal levels. This mediator enables the system to achieve low power consumption without sacrificing too much signal quality.
2Duration of action of moving object
If the bias current for the amplifier is reduced to extend battery life, then battery life is extended, but the amplifier becomes more sensitive to noise
Solution Approach 1:
The voltage transformer performs preliminary action by stepping up the input voltage before the signal enters the low-current amplifier stage. This pre-amplification of voltage (not current) allows the subsequent amplifier to use minimal bias current while still processing adequate signal levels, thereby extending battery life without excessive noise sensitivity.
3Measurement precision
If voltage transformers are added to increase input and feedback signal voltages, then the signal-to-noise ratio is improved, but the device complexity increases
Solution Approach 1:
The voltage transformer changes the voltage parameter of the input signal before amplification. By transforming the voltage level upstream of the amplifier, the system achieves improved signal-to-noise ratio without requiring complex noise filtering or multiple amplification stages, thus limiting the increase in device complexity.
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
This approach effectively reduces the noise sensitivity of the amplifier, improves the signal-to-noise ratio, and decreases current consumption, enabling longer battery life in hearing aids without increasing power consumption.
Implementation Method 1
a first voltage transformer having a transformation ratio such that it provides an output voltage larger than the input voltage and placed in the input converter upstream of the input stage
Data Source
AI summary
In order to minimize noise and current consumption in a hearing aid, an input converter comprising a first voltage transformer and an analog-to-digital converter of the delta-sigma type for a hearing aid is devised. The analog-to-digital converter of the input converter has an input stage, an output stage, and a feedback loop, and the input stage comprises an amplifier (QA) and an integrator (RLF). The first voltage transformer (IT) has a transformation ratio such that it provides an output voltage larger than the input voltage and is placed in the input converter upstream of the input stage. A second voltage transformer (OT) having a transformation ratio such that it provides an output voltage larger than the input voltage, is optionally placed in the feedback loop of the converter. The voltage transformers (IT, OT) are switched-capacitor voltage transformers, each transformer (IT, OT) having at least two capacitors (Ca, Cb, Cc, Cd). The invention further provides a method of converting an analog signal.