C波段全集成GaN MMIC Doherty功率放大器设计

Design of a C⁃Band Fully⁃Integrated GaN MMIC Doherty Power Amplifier

采用0.25μm氮化镓高电子迁移率晶体管(GaN HEMT)工艺设计了一种全集成单片微波集成电路(MMIC)多尔蒂(Doherty)功率放大器(DPA)。采用了新型的拓扑结构,去除了传统DPA中主路放大器的阻抗变换器以及两路合成后的阻抗转换器,直接在主路输出匹配网络(OMN)中实现饱和点和回退点的阻抗的转换,采取适当的阻抗,与传统电路相比,降低了阻抗转换率,拓宽了频带。此外功率分配器也采用了新颖的拓扑结构,减少了元器件的使用,并且在DPA的匹配网络中使用集总电感的电容降低版图的面积。设计了一款工作在4.6~5.4 GHz的Doherty类功放,版图后仿真结果显示,饱和输出功率为40 dBm,饱和点漏极效率DE为58.9%~61.3%,6 dB回退点的漏极效率为38.3%~45%,增益为8.4~11.3 dB,版图面积为2.4 mm×1.1 mm。

A fully integrated monolithic microwave integrated circuit(MMIC)Doherty power amplifier(DPA)is designed using 0.25μm GaN HEMT technology.A new topology is adopted,where the impedance converter of the main amplifier and the impedance converter after the two⁃way synthesis are removed,and the impedance conversion of the sa⁃turation point and the backoff point is directly realized in the main output matching network(OMN).Additionally,ap⁃propriate impedance is adopted,which reduces the impedance conversion rate and broadens the frequency band com⁃pared with the traditional circuit.The power divider also adopts a novel topology,which reduces the use of components.On the other hand,lumped inductance capacitors in the matching network of the DPA reduce the layout area.A Doherty power amplifier operating at 4.6~5.4 GHz is designed.The post⁃layout simulation results show that the PA achieves a saturated output power of 40 dBm,a drain efficiency at the saturation point of 58.9%~61.3%,a drain efficiency at the 6 dB back⁃off point of 38.3%~45%,and a gain of 8.4~11.3 dB.The layout area is 2.4 mm×1.1 mm.