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Digital Amplifiers Audio Power Amplifier

Digital Amplifiers Audio power amplifier

Digital amplifiers (also known as the ding class amplifiers) are audio power amplifiers that amplify audio signals using switch technology. The amplifier was introduced in the 1970s, but the climate was not formed at the time because of the sound quality. After more than two decades, with the development of electronic technology and components manufacturing process, people's awareness of environmental protection has been enhanced and digital amplifiers have reemerged. Due to the digital amplifier power amplifier stage work in switching state, amplifier has a small, lightweight, high efficiency, large output power, calorific value is small, and many other advantages, has become a main development trend of audio power amplifier. To meet this trend, many semiconductor manufacturers in the world have developed special integrated circuits for different USES for digital amplifiers. Containing butyl including only the output level of integrated circuit, PWM analog signal input processor (driving integrated circuit), digital signal input of the PWM processor (driving integrated circuit), and will drive circuit and the output stage all integrated on a chip monolithic fully integrated circuits, in order to meet the constitute the needs of a variety of different USES digital amplifier. Different integrated circuits should be selected according to their use.

(1) make a headphone amplifier

Given the low power required for headphones, the power voltage need not be too high, just less than 5V. In order to reduce the size of the amplifier, all circuits should be integrated into a single chip integrated circuit. For example, choose NJU8721, NJU8725, TI company's TPA2000D4 produced by new Japan wireless company. (2) production of power amplifiers that drive small loudspeakers

This kind of situation can choose the output power in 1W ~ 10W single piece full set into circuit. Such integrated circuits include yda131-e of yamaha, TA2021 of Tripath, TPA2000D2 of TI, TDA7480 of ST microelectronics co., LTD. In these amplifiers integrated circuits, some of the integrated circuits are powered by a battery of four or five cells, and the speaker can produce enough volume in 24 hours.

(3) digital amplifier for digital signal input

In this case, the digital input PWM processor and the output level integrated circuit of the ding class can be combined. The combination of the digital input PWM processor and the grid drive combined with high power MOS - FET can also be used. But for the latter scheme, the ideal voltage stabilized power supply must be used.

Due to the resolution of the width of the PWM signal by rushed there is a limit, will ensue quantization noise, so you have to use more than three order type high-order noise reducing such as plastic audio technology with sound field.

(4) make analog signal input digital amplifier

At this time, the analog input PWM processor should be selected to convert the analog signal into PWM digital signal. Then the output level or the gate drive and the output of the MOS - FET are added.

Since there are usually negative feedback, the requirements for power supply need not be too high. The power supply of the capacitor input rectifier circuit is sufficient.

(5) the output is greater than 100W

In this case, the output level integrated circuit of ding class has not been able to meet the requirements of high power output, and the combination mode of the grid driven centralized circuit and MOS - FET must be used. It is very important to choose MOS - FET at this time. The MOS - FET recommended in this grid drive IC data table should be selected as far as possible. Recently, sanyo electric has developed a hybrid integrated circuit, stk210-030, which is dedicated to power level.