Class-D Amplifier Tri-Wave Scaling for Linearity at Voltage Switching
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Solution Overview
Problem
Mobile devices require high power efficiency to extend battery life, but using switching amplifiers like class-D amplifiers can lead to issues with quiescent current, compromising amplifier linearity.
Innovation Solution
An amplification device that includes a pulse generation circuit, driver circuit, and tri-wave generation circuit to generate and adjust signals based on multiple operating voltages, ensuring the duty ratio of output signals remains consistent during voltage changes, thereby maintaining linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If switching amplifiers (class-D amplifiers) are used to achieve high power efficiency, then power efficiency is improved, but quiescent current becomes an issue and amplifier linearity is compromised
Solution Approach 1:
The patent implements dynamic adjustment of the tri-wave signal level in proportion to changes in operating voltages. When the first pair of operating voltages is switched to a second pair, the tri-wave generation circuit dynamically adjusts the signal level to maintain consistent duty ratio, thereby preserving amplifier linearity while enabling voltage switching for power efficiency
Solution Approach 2:
The patent changes the level parameter of the tri-wave signal in proportion to the changes in operating voltages. By adjusting this parameter dynamically during voltage switching, the system maintains the duty ratio of output signals consistent across different voltage levels, resolving the linearity issue while achieving power efficiency through voltage switching
2Loss of energy
If multi-level operating voltages are used to reduce quiescent current, then quiescent current is reduced, but amplifier linearity is compromised
Solution Approach 1:
The system dynamically adjusts the tri-wave signal level based on the currently active pair of operating voltages. This dynamic adaptation ensures that regardless of which voltage level is active, the duty ratio remains consistent, maintaining linearity while enabling low quiescent current operation through multi-level voltage switching
Solution Approach 2:
The level of the tri-wave signal is changed in proportion to the operating voltages being used. This parameter adjustment compensates for the effects of multi-level voltage switching, ensuring that the amplifier maintains linear operation across different quiescent current levels
Data Source
AI summary
An amplification device including: a pulse generation circuit configured to generate a pulse signal from an input signal and a tri-wave signal; a driver circuit configured to output an output signal corresponding to the pulse signal, based on a first pair of operating voltages among a plurality of operating voltages; and a tri-wave generation circuit configured to generate the tri-wave signal, and to adjust a level of the tri-wave signal in proportion to a second pair of operating voltages, when the first pair of operating voltages is changed to the second pair of operating voltages.