| Audio power amplifier is widely used in high performance audio systems, stereo phonographs, servo amplifier and instrument systems. Nowadays, people emphasize high power and high efficiency as well as high fidelity feature of audio power amplifier. So it is worth to design an audio power amplifier with the features of high power and high efficiency.The paper has designed a new-type of audio power amplifier. There are so many opportunities to develop and apply, because it is still at study phase. The design in my paper has good performance to use. We can apply it to portable electronics such as cellular, CD, DVD, MP3 players, PAD'S, some other portable electronics, etc.After studying power amplifier, in this paper, I introduce the kinds of power amplifier. First, I introduce the familiar linear and non-linear power amplifier, and then analyze advantages and disadvantages of this amplifier. I compared the characters of traditional class D power amplifier and the amplifier that is based on self-oscillating theory. Next, I refer to the structure of SCOM class-D audio power amplifier that is based on self-oscillating which is studied in my paper.The Cass D power amplifier in this paper, which is called Synchronized Controlled Oscillated Modulator (SCOM), is designed based on self-oscillating and synchronized controlled theory. The SCOM consist of operational, comparer, power driver, filter circuit and output stage. Audio signal is resumed by the inductance in speaker, and it saves arrears of chip. I designed an operational amplifier and a comparer innovatively with good characters that can be used in SCOM. I finished all the stimulations in this design. Powered by one power supply, bridge-tied load is used in order to improve THD and output power. Feedback circuit is used to improve linearity and PSRR. It can save the arrear of the chip and the cost because this circuit utilizes filter free modulator. Is has achieve all requests after test and test loading with a speaker of8Ω+ 20μH .I choose EDA tools provide by CADENCE to finish the circuit and layout design. The process of HNEC250G_PCELL (one poly and four metals) is selected in my design. The output power is 0.5W, the efficiency is higher than 70%, THD is small than 1 % and the area of chip is 480μm×300μm. All of these satisfy the requests of design. |
PDF Full Text Request