双模式控制防失真K类音频功率放大器设计

摘要

A dual mode control , anti distortion , ultra low EMI , internal integrated boost circuit is designed to realize the high vol-ume output high efficiency audio power amplifier . The system can be used to control the amplifier ’ s work in the distortion mode or normal mode according to the size of the output signal , adjust the gain to achieve anti distortion function automatically . The circuit is realized by 0 . 5 μm CMOS CSMC process . The test results show that: under the condition of 5 V power supply voltage , load RL=8 Ω+33 μH , the power amplifier can maintain the Total Harmonic Distortion+Noise ( THD+N ) in 0 . 2% with the input signal range from 0 V to 3 . 3 V , the largest output power is 2 W . The power amplifier can also provide 2 W output power when the lithi-um battery voltage drops which is suitable for the application of portable products .%提出了一种具有双模式控制、防失真、超低 EMI、内部集成升压电路的高效率音频功率放大器。系统可通过一线脉冲方式控制放大器工作在防失真模式或普通模式，其中防失真功能通过输出信号的大小自动调整增益实现。电路采用 CSMC 0.5μm CMOS 工艺实现，测试结果表明：在电源电压5 V、输出端接感性负载 RL=8Ω+33μH 的条件下，该功放能够在0～3 V 的信号输入范围内保持总谐波失真加噪声(THD+N)仅为0.2%，最大输出功率2 W。该功率放大器在锂电池电压下降时也能持续提供2W 的输出功率，适合便携式产品的应用。