Explore the workings of current-mode Class-H amplifiers, their efficiency, performance, types, and role in modern audio applications.
Introduction
Current-mode Class-H amplifiers are a type of audio amplifiers that offer high efficiency and improved audio performance. These amplifiers, which are often found in audio power amplifiers and battery-powered devices, dynamically adjust the supply voltage to the output stage to reduce power loss.
Working Principle of Current-Mode Class-H Amplifiers
In a current-mode Class-H amplifier, the audio signal is first processed by a modulator. This modulator converts the input audio signal into a current signal, hence the term ‘current-mode.’ The modulated current signal is then fed to the output stage.
Dynamic Power Supply
The unique feature of a Class-H amplifier is its dynamic power supply. The supply voltage to the output stage is not constant, but rather it changes according to the demands of the audio signal. The output stage only gets the voltage it needs to amplify the current signal, which is derived from the input audio signal.
- Efficiency: This dynamic adjustment of the supply voltage significantly improves the efficiency of the amplifier, reducing heat generation and power waste.
- Performance: Furthermore, since the output stage only amplifies the current signal, the distortion and noise typically associated with voltage amplification are greatly reduced, leading to superior audio performance.
Two-Level and Multi-Level Class H
There are two types of Class-H amplifiers: two-level and multi-level. In a two-level Class-H amplifier, the supply voltage can be set to one of two levels, while a multi-level Class-H amplifier can switch between more than two levels, offering even greater efficiency and flexibility.
Conclusion
Current-mode Class-H amplifiers have become popular in modern audio applications due to their high efficiency and excellent audio performance. By dynamically adjusting the supply voltage according to the audio signal’s demands, they offer a solution that is both power-efficient and high-performing.
