Class G/H amplifiers refer to different designs that boost Class AB output stages. Both denominations, either G or H, are interchangeable. Yet, the terms vary from one manufacturer to another. Experts commonly use these devices in large audio amplifiers. They have effective techniques that allow them to achieve greater efficiency with low distortion.
Class G Amplifiers
Class G amplifiers use rail switching to reduce power consumption and increase productivity. These amps offer several power rails at different voltages. In addition, you can switch between one and the other when the signal output approaches each level. This type of amplifier becomes more efficient as it reduces the wasted power at the output transistors.
Keep in mind that each amplifier is efficient in its own way. The Class D amplifier, for instance, has electromagnetic interference effects, but not the rest of them. In contrast, Class G amps tend to be more efficient than the Class AB amp, but less efficient than the Class D amplifiers nevertheless.
Class H Amplifiers
People also know class H amplifiers as rail trackers. These are able to create a variable analog supply rail by modulating the supply rails. As a result, the rails are only a few volts larger than the signal tracking. The output stage works efficiently all the time because of the circuit’s ability to keep the T2 and T4 rail transistors limited until it needs a higher voltage due to a voltage peak. Class H amps are like two amplifiers in series.
Both Class G and H: Characteristics
Both Class G and Class H amplifiers provide enhancement to the basic AB design. The Class G amp uses several power supply rails that range between diverse voltages. Firstly, they can switch back and forth to higher and lower voltages when needed. Secondly, they switch to a higher voltage when the audio signal wave has a peak value higher than the level of the supply voltage. In a similar manner, they switch back to a lower voltage when the peak value of the audio signal decreases. By doing this, they reduce the usual power consumption and the heat caused by the wasted power.
Class G/H amplifiers require complex power supplies that increase the cost. Class H amps improve over Class G amplifiers by varying the supply voltage. The power supply voltage tracks the peak level of the signal to reach a slightly higher audio wave. When the signal peak value falls below the desired level, it returns to its initial state.
