Amplitude-Controlled Amplifier Circuit for BTL Switching Loss Reduction

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Bridge-tied-load (BTL) amplifier configurations are inefficient at low power signal levels due to switching losses in class-D amplifiers and power consumption issues, particularly in portable devices where power efficiency is crucial.

Innovation Solution

An amplifier circuit that dynamically transitions between BTL and single-ended modes based on output signal amplitude, with a controller managing the operation to minimize power consumption by disabling one driver at low amplitudes and using class-D amplifiers only when necessary, thereby optimizing power efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If BTL configuration is used to drive transducer with high power, then power output capability is improved, but power consumption increases

Engineering Contradiction:

Improvepower output capabilityVSAvoidpower consumption

Core Design Contradiction:

PowerVSUse of energy by moving object

Solution Approach 1:

The amplifier dynamically switches between BTL and single-ended modes based on the amplitude of the input signal. For low-amplitude signals, only one driver operates in single-ended mode to reduce power consumption. For high-amplitude signals, both drivers operate in BTL mode to provide sufficient power output capability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The amplifier changes its operating parameters (mode of operation) based on signal conditions. The controller monitors the input signal amplitude and adjusts the operating mode accordingly, transitioning from single-ended mode at low amplitudes to BTL mode at high amplitudes, thereby optimizing the trade-off between power consumption and power output capability.

Inventive Principle:

Principle #35Parameter changes

2Power

If class-D amplifiers are used in BTL configuration, then power output is improved, but switching losses increase

Engineering Contradiction:

Improvepower outputVSAvoidswitching losses

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The amplifier uses periodic switching action characteristic of class-D amplifiers but applies it selectively. The class-D switching is enabled only when high power output is required (BTL mode with high-amplitude signals). For low-amplitude signals, the amplifier operates in single-ended mode where switching losses are avoided or minimized, thus reducing overall energy loss while maintaining power output capability when needed.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS11271532B1Amplifiers

Publication Date: 2022.03.08 CIRRUS LOGIC INC

AI summary

This application relates to an amplifier selectively operable in first or second modes. The first mode is a BTL mode with first and second output drivers (103p, 103n) both active to generate respective driving signals that vary with an input signal. The second mode is an SE mode, where the first output driver (103p) is active to generate a driving signal at and the output of the second driver (103n) is held constant. A controller (201) selectively controls the mode based on an indication of output signal amplitude. In the first mode, a ratio of magnitude of the two driving signals varies with the indication of output signal amplitude, i.e. the magnitudes of the two driving signals may vary so as to be not equal.