Active Output Driver Supply Compensation for Battery Noise

Solution Overview

Problem

Hearing aids and portable audio devices using Class D output drivers face audio performance degradation due to fluctuations in battery voltage caused by variable current loads, leading to unwanted volume variations and noise, which cannot be effectively addressed by adding filtering components or larger batteries without compromising size and portability.

Innovation Solution

An electronic system that includes an analog-to-digital converter to sample fluctuating voltages, control logic to generate amplitude correction signals, and an output driver to regulate power supply based on these signals, using a sigma-delta modulator to reduce noise by pushing it above the human hearing range, and optionally employing a voltage regulator to maintain a stable voltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If filtering components or a larger battery are added to a portable audio device, then voltage stability is improved, but device size and weight increase

Engineering Contradiction:

Improvevoltage stabilityVSAvoiddevice weight

Core Design Contradiction:

Stability of the object's compositionVSWeight of stationary object

Solution Approach 1:

The patent replaces the mechanical/physical approach of using larger batteries or filtering components with an electronic control system. The output driver actively monitors and adjusts its operation based on detected voltage fluctuations, using digital signal processing to compensate for supply variations without adding physical mass to the device.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system dynamically changes operating parameters of the output driver based on detected voltage conditions. By monitoring voltage fluctuations and adjusting drive signals in real-time, the system adapts to varying supply conditions, maintaining audio performance without requiring a larger battery or additional filtering hardware.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If filtering components or a larger battery are added to a portable audio device, then voltage stability is improved, but device size increases

Engineering Contradiction:

Improvevoltage stabilityVSAvoiddevice volume

Core Design Contradiction:

Stability of the object's compositionVSVolume of moving object

Solution Approach 1:

The patent replaces the mechanical/physical approach of using larger batteries or filtering components with an electronic control system. The output driver actively monitors and adjusts its operation based on detected voltage fluctuations, using digital signal processing to compensate for supply variations without adding physical mass to the device.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system dynamically changes operating parameters of the output driver based on detected voltage conditions. By monitoring voltage fluctuations and adjusting drive signals in real-time, the system adapts to varying supply conditions, maintaining audio performance without requiring a larger battery or additional filtering hardware.

Inventive Principle:

Principle #35Parameter changes

3Loss of energy

If Class D output drivers are used for high power efficiency, then energy consumption is reduced, but audio performance degrades due to voltage fluctuations

Engineering Contradiction:

Improvepower efficiencyVSAvoidaudio performance

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where the output driver continuously monitors the supply voltage and detects fluctuations. Based on this feedback, the system dynamically adjusts its operation to compensate for voltage variations, maintaining consistent audio output levels and preventing audible artifacts while preserving the high efficiency benefits of Class D operation.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs preliminary detection and correction of voltage fluctuations before they can significantly impact audio output. By monitoring supply voltage in advance and preparing compensation signals, the system prevents performance degradation rather than reacting to it after the fact, ensuring consistent audio quality throughout voltage transitions.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS10117035B2Active output driver supply compensation for noise reduction

Publication Date: 2018.10.30 SEMICON COMPONENTS IND LLC

AI summary

An electronic system, in some embodiments, comprises: a power source; a load coupled to the power source; an analog-to-digital converter, coupled to the power source and the load, that samples a fluctuating voltage supplied by the power source and generates a digital representation of said fluctuating voltage; control logic, coupled to the analog-to-digital converter, that generates an amplitude correction signal based on said digital representation of the fluctuating voltage and on a target voltage; correction logic, coupled to the control logic, that uses the amplitude correction signal and an audio signal to generate a switch control signal; and an output driver, coupled to the correction logic, that controls coupling between the power source and the load based on the switch control signal.