The function and working principle of power amplifier

发表于2020-07-14

  1. A power amplifier, called a "power amplifier," is an amplifier that produces the maximum power output to drive a load (such as a speaker) at a given distortion rate. The power amplifier plays the key role of "organization and coordination" in the whole sound system, which determines whether the whole system can provide good sound quality output to a certain extent.

    Function of power amplifier

    Preamplifier: The function of the preamplifier is to output the program signal sent by the signal source to the rear amplifier after the necessary processing and voltage amplification. It's like a fork in the road. It controls which audio signals are connected to the amplifier and which are disconnected from the amplifier.

    Background amplifier: The function of the background amplifier is to perform simple power amplification. Its function is to amplify the signal from the front stage as faithfully as possible. The requirement for the background is that the amplification factor should be as high as possible and the distortion of the amplified signal should be as low as possible. In addition to amplifying circuit, protective circuit is also designed, such as short circuit protection, overvoltage protection, overheat protection, overcurrent protection.

    Amplifying volume: The main function of power amplifier is to amplify the volume, which is generally used for household audio and various audio equipment.

    Improved sound quality: In addition to increasing volume, power amplifiers also improve sound quality. However, it should be noted that only when the power amplifier is properly installed can it effectively improve the sound quality of our sound system.

    Second, the working principle of power amplifier

    Power amplifiers actually work simply by amplifying various sound signals played by the sound source and pushing the speaker to produce sound. We explain in detail how class D amplifiers commonly work:

    Class D amplifier is a kind of amplifier that inputs analog audio signal or digital information into pulse width modulation or pulse density modulation pulse signal and USES pulse signal to control high power. Class D amplifier is an amplifier mode in which the amplifier element is in the on/off state. The amplifier is off when there is no signal input

    Electric power. During the operation, the input signal is used to saturate the transistor, and ACTS ACTS as an on-on switch to connect the power to the load. The ideal transistor consumes no power because there is no saturation voltage drop. In practice, the transistor always consumes some power with a small saturation voltage drop. This power consumption is related only to the characteristics of the pipe and not to the size of the signal output, so it is particularly useful for super power applications. Ideally, class D amplifiers are 100 percent efficient, class B amplifiers are 78.5 percent efficient, and class A amplifiers are only 50 or 25 percent efficient, depending on the type of load.

    Class D amplifiers were actually only switch-on; in the early days, they were used only for switching control circuits of relays and motors. But with the development of digital audio technology, ways to amplify audio using hi-Fi have become increasingly clear.