S波段高效F类/逆F类GaN HEMT功率放大器设计

为了解决F类和逆F类（F-1类）功率放大器设计过程中受晶体管寄生参数影响，导致功放效率低以及输出匹配电路结构复杂的问题，提出了一种新型的输出匹配电路结构.首先，在直流偏置线中加入谐波调谐功能，避免单独设计谐波控制电路；其次，为满足F类和F-1类功放在器件本征漏极端所需的阻抗状态，匹配寄生参数呈现的封装端谐波阻抗，采用一段L型传输线结构代替传统的L-C集总元件寄生补偿方法；最后，由两段串联的传输线实现最优基波阻抗与50 Ω负载间的匹配.为验证方法的有效性，采用CGH40010氮化镓高电子迁移率晶体管（Gallium nitride high electron mobility transistor，GaN HEMT）器件，设计并加工了两款工作在2.4 GHz的F类和F-1类功放.测试结果显示:F类功放的峰值功率附加效率（power added efficiency，PAE）为75.5%，饱和输出功率为40.8 dBm；F-1类功放的峰值PAE为77.6%，饱和输出功率为40.3 dBm.该方法降低了电路复杂度和设计难度，可以较容易地补偿晶体管寄生参数，功放在高频工作时的效率得到提升，为利用GaN HEMT器件设计高效功放提供了一种可行的方案.

Design of S-band high-efficiency class-F/class-F-1 GaN HEMT power amplifiers

In order to solve the problem that the class-F and the inverse class-F (class-F-1) power amplifiers (PAs) affected by the parasitics of the packaged transistor, resulting in a low efficiency performance and complicated circuit structure, a novel output matching circuit is proposed. Firstly, the DC bias line with harmonic tuning was equipped in the harmonic control circuits, thus simplifying the complexity of the harmonic control circuits. Then, an L-type transmission line circuit was adopted to replace the traditional L-C lumped components, which matched the harmonic impedances presented by the parasitics, thus the class-F or class-F-1 harmonic impedance conditions at the intrinsic drain of transistor can be realized. Finally, two series transmission lines transformed the optimum fundamental impedance into 50 Ω load. For demonstration, the class-F PA and class F-1 PA using the CGH40010 GaN HEMT device are designed and fabricated, which operating at 2.4 GHz. Measurement results show that the peak power added efficiency (PAE) of the class-F PA reaches 75.5%, the corresponding output power is 40.8 dBm; the peak PAE of the class-F-1 PA is 77.6%, and the corresponding output power is 40.3 dBm. The proposed method simplifies the complexity of the PA circuit, can easily compensate the parasitics of transistor, and provides a feasible solution for designing high efficiency PAs using GaN HEMT active devices.