28 GHz GaN Power Amplifier MMIC Design

The demand for high communication capacity,low latency,and massive connectivity in mobile communications has driven the rapid development of fifth-generation mobile communication technology(5G),which is based on the Sub-6 GHz band and has brought a great upgrade to people’s communication experience.In pursuit of higher communication capacity,millimeter wave communication systems have attracted the research of many scholars.Power amplifiers(PAs)are an important part of communication systems,and the millimeter wave band poses many challenges to PA design,such as power output level,broadband matching design,efficiency level,and heat dissipation issues.In this paper,two PA monolithic microwave integrated circuits(MMICs)operating at 24-28 GHz and 34-36 GHz are developed and designed around millimeter-wave GaN PAs.First,a two-stage high-efficiency GaN PA MMIC operating at 24-28 GHz is developed,and an improved elliptical response output matching network design method is proposed to improve the out-of-band rejection of the PA.The experimental test results show that this PA MMIC has a good out-of-band rejection performance and achieves a saturation power added efficiency(PAE)higher than 29%in the 24-28 GHz range,with a peak PAE of 36.3%at 27GHz.The saturated output power is in the range of 33.8-35.6 d Bm in the operating band.For a100 MHz five-carrier Long Term Evolution(LTE)modulated signal,the PA achieves an Adjacent Channel Leakage Ratio(ACLR)better than-40 d Bc in the operating band with digital pre-distortion techniques.The PA MMIC footprint is 2.4 x 1.0 mm~2.Then,a two-stage high-efficiency GaN high PA MMIC operating at 34-36 GHz is designed,and the output network of this PA is optimized for power combining and matching performance in order to improve the efficiency of the PA.The simulations show that the matching network of the PA MMIC has low in-band loss and achieves good base-wave matching,with peak PAE of 28%and power gain of 11 d B at a saturation output power of 36.1 d Bm in the 34-36 GHz band.The PA MMIC layout area is 3.7×1.8 mm~2.