【作者】 陈艳；

【导师】 应建华；

【作者基本信息】 华中科技大学 ， 微电子学与固体电子学， 2006， 硕士

【摘要】 音频功率放大器广泛应用于家庭影院、音响系统、立体声唱机、伺服放大器等电子系统中。人们在追求高保真度音频功放的同时,也希望功放有大的输出功率和高效率。因此,设计一种失真度小,输出功率大,效率高的音频功放也有很重要的现实意义。本文介绍了一种额定输出功率为20W的音频功率放大器芯片的设计。该芯片采用了AB类推挽输出级,内部有Miller补偿,可保证闭环稳定性。芯片内部设有过温保护电路,过流保护电路和过压保护电路,对芯片实施了三重保护,在输出大功率或驱动感性负载的同时,可保证芯片不被损坏。芯片能够在±25V的电源电压下为4?或8?的负载提供20W的输出功率。该电路设计采用了先进的电路结构,保证了大功率输出时的低失真度,同时具有100dB的开环增益,4A的电流容量,10V/μS的转换速率和40kHz的功率带宽等性能指标。本文对各模块性能指标的设计做了详细介绍,同时也对版图设计注意事项做了简单介绍,还给出了芯片在典型应用下系统仿真的波形。最后,提出了芯片功能改进的方案及相应的后续工作。该芯片采用4μm Bipolar高压工艺实现。利用Cadence Spectre对各部分电路进行了仿真,仿真结果完全满足设计要求,同时利用Cadence Virtuoso进行版图绘制。目前该芯片正在流片。更多还原

【Abstract】 Audio Power Amplifier is widely used in high performance audio systems, stereo phonographs, servo amplifiers and instrument systems. Nowadays, people emphasize high power and high efficiency as well as high fidelity feature of audio power amplifier. So it’s worth to design an Audio Power Amplifier with the features of high power and high efficiency.In this paper, a 20 watt audio power amplifier has been developed, which has class-AB output stage, and with Miller compensation internal to guarantee the stability of close loop. The chip has internal current limit、thermal shutdown and over-voltage protection circuit. When it is delivering high output power to the load or driving nonlinear reactive loads, the degradation of the output transistor or catastrophic failure of the whole circuit may happen without those internal protection circuit . It’s capable of delivering 20 watt of output to a 4 ? or 8 ? load at±25 V supplies. The design takes advantage of advanced circuit techniques and process technology to achieve extremely low distortion levels even at high output power. The chip also has the following features: open loop gain of 100dB, current capability of 4A, slew rate of 10V/μs and power bandwidth of 40 kHz.Design of each block is described in detail, layout consideration is also presented in brief and the simulation waves are given. At last , the improvement of chip features is proposed as the feature work.The 4μm High Voltage Bipolar process is used to fabricate this chip. We use Cadence Spectre to run simulation, and results of system simulation indicate that the performance of this circuit meets exactly with the design goals. Meanwhile, we use Cadence Virtuoso to edit layout, and the chip has been in fabrication now.更多还原