325 MHz连续波<styled-content style-type="number">2500</styled-content> W GaN HEMT功率放大器

刘欢; 魏洪涛; 蔡道民

doi:10.11884/HPLPB202638.260035

摘要: 本文基于GaN HEMT器件，设计和制作UHF频段的超大功率、高效率的固态射频微波放大器，以满足科学、医疗和工业应用。采用0.8 μm GaN HEMT工艺，借助微波软件进行电、磁和热等设计和仿真等，首先在器件层面上优化器件的源漏间距、场板结构和衬底减薄等尺寸，器件击穿电压提升400 V；其次在装配工艺层面优化AuSb焊料烧结工艺，提升大功率管芯烧结于金刚石铜管壳成品率，空洞率小于5%，有效降低热阻；最后在电路制作层面选用高低不同的介电常数PCB和采用谐波调谐技术，实现准方波电压和半正弦电流波形，降低器件功耗，提升漏极效率。调测结果如下：在工作电压50 V、栅极电压−3 V、频率325 MHz、连续波工作状态下实现了饱和输出功率大于2 500 W，功率附加效率大于85%，功率增益大于19 dB，热阻降低至0.20 ℃/W，效率指标比同类LDMOS高10%以上。成功实现了GaN HEMT放大器向低频领域的扩展，可广泛应用于工艺加热、医疗和大科学装置等领域。

Abstract:

Background The escalating demand for ultra-high-power radio frequency(RF) sources in scientific research (e.g., particle accelerators), industrial heating, and advanced medical equipment necessitates breakthroughs in solid-state microwave amplifier technology. While GaN HEMT devices offer superior power density, extending their operation to lower UHF bands while maintaining extreme efficiency remains a critical challenge due to thermal management limitations and waveform engineering complexities.

Purpose This study aims to design and fabricate an ultra-high-power, high-efficiency solid-state microwave amplifier operating in the UHF band based on GaN HEMT technology, specifically targeting continuous-wave(CW) output exceeding 2500W with a drain efficiency greater than 85%.

Methods Utilizing a 0.8 μm GaN HEMT process, comprehensive electro-thermal co-design and simulation were conducted. At the device level, source-drain spacing, field plate structures, and substrate thinning were optimized to enhance breakdown voltage. At the assembly level, AuSb solder sintering processes were refined to improve die-attach yield on Cu-diamond heat sinks, minimizing voids. At the circuit level, a hybrid PCB stack-up with varying dielectric constants and harmonic tuning networks were implemented to shape quasi-square voltage and half-sinusoidal current waveforms, thereby reducing power dissipation.

Results Under a CW operating condition of 325 MHz with a drain voltage of 50V and gate voltage of -3V, the fabricated amplifier achieved a saturated output power of >2500 W, a power-added efficiency (PAE) of >85%, and a power gain of >19 dB. The thermal resistance was successfully reduced to 0.20 ℃/W, and the efficiency outperformed comparable LDMOS-based technologies by over 10%.

Conclusions The successful demonstration of this GaN HEMT amplifier not only validates the feasibility of extending high-performance GaN devices into the low-frequency UHF regime but also provides a robust technological solution for applications requiring multi-kilowatt RF power, such as industrial heating, medical systems, and large-scale scientific facilities.

325 MHz连续波2500 W GaN HEMT功率放大器

325 MHz continuous wave 2500 W GaN HEMT power amplifier