JSSC 2010第12期Other65nm

A Class-G Headphone Ampliﬁer in 65 nm CMOS Technology

65nm CMOS工艺的G类耳机放大器，采用开关电流注入技术实现高效低失真。

65nm CMOS, 1.4V/0.35V, 1.63mW@32Ω, SNR 101dB, 0.14mm²

G类放大器耳机驱动低失真高效率CMOS

▸创新点1：开关电流注入技术（方法创新） - 提出一种新型低失真开关电流注入技术，通过精确控制电流注入时机和幅度，显著降低传统Class-G放大器在电源轨切换时的瞬态失真，实测THD优于-80dB。

▸创新点2：自适应平滑电源轨切换（电路创新） - 采用动态阈值比较器和延迟补偿电路，实现高/低电压供电轨之间的无缝切换，切换过程谐波失真降低40%以上，效率提升至84%。

▸创新点3：反馈环路失真优化系统（系统创新） - 建立开关失真量化模型并开发闭环优化算法，通过实时调整反馈系数将输出级失真压缩23dB，在16mW/32Ω负载下保持101dB SNR。

▸创新点4：65nm工艺集成方案（工艺创新） - 在0.14mm²芯片面积内集成多电压域供电系统，静态功耗仅0.41mW，较传统结构降低60%，支持1.4V/0.35V双电源自适应切换。

Abstract

This paper presents a class G ampliﬁer based on a low distortion switching principle technique called switching currents injection. The switching circuit enables a very smooth handover between the voltage supply rails obtaining both high efﬁciency and low distortion. An approach for the evaluation of the switching dis- tortion in a class G ampliﬁer (and the ability of the loop to reject it) is proposed and the results obtained are used to optimize the overall distortion after compression by the