What is the power amplifier?
Power amplifier, referred to as 'power amplifier' for short, refers to the ability to generate a maximum power output to drive a certain load (Such as speakers)The amplifier. The power amplifier plays a pivotal role of 'organization and coordination' in the entire audio system, which to some extent dominates whether the entire system can provide good sound quality output. The power amplifier can be said to be the largest family of all kinds of audio equipment. Its function is mainly to amplify the weak signal input by the sound source equipment, generate enough current to push the speaker to replay the sound. Considering power, impedance, distortion, dynamics, different use ranges and control and adjustment functions, different power amplifiers also have different internal signal processing, line design and production process. What is the power amplifier? Power amplification uses the current control action of the triode or the voltage control action of the FET to convert the power of the power supply into a current that changes according to the input signal. Because sound is a wave of different amplitude and frequency, that is, AC signal current, the collector current of the triode is always β times of the base current, and β is the AC magnification of the triode, if a small signal is injected into the base, the current flowing through the collector will be equal to β times of the base current, and then the signal will be isolated by a direct capacitor to obtain the current (Or voltage) It is a large signal of the original β times, and this phenomenon becomes the amplification effect of the triode. After constant current and voltage amplification, power amplification is completed. In a communication device, the last stage of a multi-stage amplifier always carries a certain load, such as making the speaker sound, or connecting the signal to a long-distance line for long-distance transmission, etc, this requires the amplifier to output a certain signal power. Therefore, this level of amplifier is called a power amplifier. The power amplifier and the voltage amplifier have something in common, that is, the two are to amplify the electrical signal, so the circuit structure is basically the same, such as the input loop is the same as the signal source and the grid bias series, the output loop is also connected in series with the screen power supply, and the analysis method is basically the same. It is also illustrated and equivalent circuit, but the difference is that, voltage amplification requires a large convergence of the output voltage, while power amplification requires a certain amount of power, that is, the amplitude of the output voltage and current is required to be large. Therefore, how to make the load get as much output power as possible is the main requirement for the power amplifier. Therefore, the standard for measuring the performance of power amplifiers is mainly to obtain maximum output power and higher efficiency as much as possible under the condition of allowable nonlinear distortion.