L波段F类高效率载片式功率放大器设计

Design of L-band class-F high efficiency carrier power amplifier

摘要:

为解决传统F类功率放大器受晶体管输出电容和输出电感影响,导致调谐匹配网络结构复杂的问题,提出了一种紧凑型的输出调谐匹配电路结构。通过分析基波匹配电路的阻抗特性,在谐波频率处可将其等效为一段有限的到地电抗。在设计谐波匹配电路时,将该电抗元件与谐波匹配电路进行协同设计,避免引入多余的元件来消除基波匹配网络对谐波匹配网络的影响,减小了功放的整体面积。最后,仅引入一个LC串联谐振网络,实现对输出二次\\三次谐波的控制以提高输出效率。基于该电路结构,采用0.25 μm GaN HEMT管芯设计了一款L波段高效率功率放大器,并且使用内匹配技术在7 mm×8 mm铜-钼-铜载片上实现。实测结果表明,在漏源电压28 V、10%占空比的脉冲输入的工作条件下,该功率放大器在1.18~1.42 GHz频带内实现饱和输出功率48.1~48.4 dBm,功率附加效率61%~63%,功率增益大于26 dB。该结构在提高效率的同时,降低了电路复杂度。

Abstract:

To solve the problem that the tradition class-F power amplifier is affected by transistor output capacitance and output inductance, resulting in complicated tuning circuit, a compact output harmonic tuned matching circuit is proposed. By analyzing the impedance characteristics of the fundamental wave matching circuit, equivalent to a finite reactance to the ground at the harmonic frequency, the reactance and the harmonic tuned matching circuit are co-designed to avoid introducing redundant elements and eliminate the influence of fundamental matching network on harmonic matching network, thus reducing the power amplifiers size. Finally, only an LC tuning network is introduced to realize the control of the output the second and third harmonics to improve the output efficiency. Based on this circuit structure, a high efficiency L-band power amplifier using 0.25 μm GaN HEMT transistor is designed and implemented on a 7 mm×8 mm Cu-Mo-Cu Carrier using internal matching technology. The measured results show that under the condition of a drain-source voltage of 28V and the input of 10% duty cycle pulse signal, the amplifier achieves the large-signal performance of 61%-63% PAE and over 26 dB power gain at a saturated power of 48.1-48.4 dBm within 1.18-1.42 GHz. The structure improves the efficiency and reduces the complexity of the circuit.