Ku波段GaN MMIC高线性功率放大器设计

Design of Ku Band GaN MMIC Power Amplifier with High Linearity

设计了一款Ku波段工作频率为13.0~15.5GHz的GaN MMIC高线性功率放大器,采用0.25μm GaN HEMT工艺,电路采用两级放大器的结构。通过两种不同的末级匹配网络的设计,对比分析匹配网络的设计对功率放大器效率与线性度的影响。一种是匹配到最佳功率附加效率(PAE)的末级匹配网络,一种则是匹配到最佳线性度的末级匹配网络(用最佳三阶交调产物与载波比值(IM3)来表示),级间和输入级匹配网络也尽量达到低损耗、高线性指标,从而提高整体电路的线性度,并尽量使得效率不恶化。测试结果表明,功率放大器的最大输出功率可以达到37.5dBm,匹配到最佳PAE的功率放大器功率附加效率均大于32%,最大可以达到36%,匹配到最佳IM3的功率放大器PAE低了2到4个百分点,线性度指标IM3则高了1到2个dBc。该测试结果表明,对于高线性功率放大器,末级匹配网络可以在最佳PAE点的基础上适当地向最佳IM3点靠近,以逼近更好的线性度指标,但若距离最佳IM3太近,PAE则会有较大的恶化。

A Ku band GaN MMIC power amplifier working at 13.0-15.5 GHz was designed and fabricated in a 0.25μm GaN HEMT technology.Two different output matching networks were employed and their influence on the efficiency and linearity of power amplifier were analyzed.The first one was matched to the best PAE while the second one was matched to the best linearity quantified by IM3.To get the best linearity and PAE,inter-stage matching network and input matching network were optimized.The test results indicate that the largest output power is up to 37.5 dBm and the PAE of circuit with output matching network is larger than 32% with a maximum of 36%.While linearity is increased by 1~2 dBc with PAE of 2~4 percent lower in the case of the best IM3 matching.It is suggested that to get the higher linearity,output matching network should be set between the best PAEand the best IM3.