JSSC 2007第12期RF & Wireless0.35μm

A 2 W CMOS Hybrid Switching Amplitude Modulator for EDGE

本文提出了一种用于EDGE极性发射机的混合开关幅度调制器，结合宽带缓冲线性放大器和PWM开关放大器，实现高效高速。

0.35μm CMOS, 3.5V, 2MHz, 88.3%效率

EDGE极性发射机混合调制器class-AB放大器PWM

▸创新点1：混合开关幅度调制器设计（方法创新）。该设计结合了宽带缓冲线性放大器作为电压源和PWM开关放大器作为依赖电流源，实现了高效率（88.3%）和高速度（2 MHz开关频率）的平衡，适用于EDGE极性发射机。

▸创新点2：新型class-AB拓扑线性放大器（电路创新）。采用独特的class-AB架构，具有高电流驱动能力（300 mA）和宽带宽（>10 MHz），显著提升了线性度和动态响应。

▸创新点3：四象限操作与超低输出阻抗（系统创新）。通过四象限操作和200 mΩ的输出阻抗设计，有效抑制了开关频率下的纹波电压（<12 mV），提升了系统稳定性和信号质量。

▸创新点4：前馈路径与PWM控制优化（方法创新）。结合前馈路径、PWM控制和三阶纹波滤波器，降低了线性放大器的电流负担，扩展了输出电压范围（0.4-3 V），支持4 Ω负载下2.25 W的最大输出功率。

Abstract

This paper presents a hybrid switching amplitude modulator for class-E2 EDGE polar transmitters. To achieve both high efﬁciency and high speed, it consists of a wideband buffered linear ampliﬁer as a voltage source and a PWM switching am- pliﬁer with a 2 MHz switching frequency as a dependent current source. The linear ampliﬁer with a novel class-AB topology has a high current-driving capability of approximately 300 mA with a bandwidth wider than 10 MHz. It can also operate on four quadrants with very low output impedance of about 200 m /10at the switching frequency attenuating the output ripple voltage to less than 12 mV /112/112. A feedforward path, a PWM control, and a third-order ripple ﬁlter are used to reduce the current burden of the linear ampliﬁer. The output voltage of the hybrid modulator ranges from 0.4 to 3 V for a 3.5 V supply. It can drive an RF power ampliﬁer with an equivalent impedance of 4 /10up to a maximum output power of 2.25 W with a maximum efﬁciency of 88.3%. The chip has been fabricated in a 0.35 m CMOS process and occupies an area of 4.7 mm /50.