Audio Amplifier Gain Control With Analog-Digital Step Compensation

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Solution Overview

Problem

Existing audio amplifiers require separate gain controls that are unintuitive and can lead to poor signal quality if used improperly, and remote control integration is limited.

Innovation Solution

A system combining analog and digital circuit elements to modify gain in response to a single user-operable control, with discrete gain steps in both domains to maintain consistent overall gain, and digital processing to compensate for analog gain and remove signal discontinuities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a single analog control is used to drive multiple analog gain stages, then the control can be operated remotely by a mobile application, but the control is not configured for remote operation and its usefulness is limited

Engineering Contradiction:
Improveremote control capabilityVSAvoidcontrol usability
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent creates a virtual copy of the physical control knob in the mobile application interface. The virtual control member replicates the appearance and functionality of the physical control member, allowing users to operate the gain control remotely through the mobile application with the same user experience as the physical interface.

Inventive Principle:
Principle #26Copying

2Adaptability or versatility

If separate gain controls are provided for wide input level range, then the input level range can be divided into smaller segments, but the controls become confusing and unintuitive to operate

Engineering Contradiction:
Improveinput level range coverageVSAvoidcontrol intuitiveness
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent merges the physical and virtual control members into a unified control system. Both control members operate the same gain control function and are synchronized, presenting a single intuitive control interface to the user rather than separate, confusing controls. The system combines analog and digital control paths while maintaining a unified user experience.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single gain control is designed to handle multiple input level ranges universally. By combining analog and digital gain stages under a single control interface, the system provides wide input level coverage (beyond the ADC input range) while maintaining intuitive operation. The control member serves multiple functions: it controls analog gain stages for high-level inputs and digital gain for lower-level inputs, adapting its behavior based on the input signal level.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If multiple analog gain stages are used to handle wide input levels, then the input level range can be extended, but signal quality deteriorates if controls are used improperly

Engineering Contradiction:
Improveinput level rangeVSAvoidsignal quality
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The system uses feedback to monitor the input signal level and automatically selects the appropriate gain stage configuration. The digital signal processor detects the input level and controls the analog gain stages accordingly, ensuring that the signal remains within the optimal range for the ADC converter. This feedback mechanism prevents improper control usage from degrading signal quality while maintaining extended input level range.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system dynamically changes the gain parameters of the analog circuit elements based on the input signal level. By adjusting the analog gain stages in response to detected input levels, the system extends the usable input range while maintaining signal quality. The digital signal processor modifies the analog gain parameters to match the input conditions, preventing clipping and distortion.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4165778B1Audio signal amplifier gain control
Publication Date: 2026.02.25 BOSE CORP
  • EP4165778B1 patent drawingFigure 1
  • EP4165778B1 patent drawingFigure 2A~2B
  • EP4165778B1 patent drawingFigure 3

AI summary

A system for controlling the gain of an input signal in an audio signal amplifier. The system includes a user-operable gain control, and analog and digital circuit elements that together are configured to modify the gain of the input signal in response to the user-operable gain control.