摘要
采用SMIC0.18μm3.3V CMOS工艺,实现了单相电源Ⅰ类线性音频功放的设计。为了提高AB类功放的效率,设计了一种新型结构的Ⅰ类线性音频功放,并理论推导了它的效率。Ⅰ类音频放大器中的电源转换器能根据输入音频信号连续调节AB类功放的功率电源电压以减小功率管上的压降。为了使单相电源下PMOS和NMOS功率管功耗同时得到优化,设计了增益变化的信号处理电路。输出级采用桥式结构,并由三级运放构成以提高线性度。测试结果表明,该功放向8Ω阻性负载提供功率在小于270mW范围内时,总谐波失真与噪声之和小于0.45%,最大效率达到70%;功率在100mW范围内时,效率比AB类提高了一倍,且测试效率曲线与理论推导吻合。
A single power supply class I linear audio amplifier is implemented in SMIC 0. 18μm 3.3 V CMOS technology. To increase the efficiency of class AB, a new class I linear audio amplifier was designed and the efficiency is derived. The power convertor in class I changes the power supply voltage of class AB continuously according to the input signal level to decrease the voltage drop on power transistors. Variable gain signal processing circuit is designed to optimize the power dissipation of both PMOS and NMOS power transistors. The output stage is composed of two bridge-tied three-stage amplifiers to improve the THD. The measured THD＋N is better than 0. 45% when output power is lower than 270 mW with 8 Ω load and the maximum efficiency is 70%. When output power is lower than 100 mW, the efficiency is doubled comparing to class AB. The measured results verify the theory.
出处
《固体电子学研究与进展》
CAS
CSCD
北大核心
2010年第3期446-452,共7页
Research & Progress of SSE
基金
国际合作项目:ADI公司项目资助
