Research On X-band GaN Switching Power Chips

Solid-state microwave technology makes military electronic systems smaller and lighter,and also has the characteristics of high reliability.As a typical representative of wide bandgap semiconductors,gallium nitride（GaN）materials are very suitable for application in the field of microwave power devices with their own material advantages,making them a hot spot in the current research and application of military electronic systems.X-band（8～12GHz）is an important frequency band for radar applications,so the research of X-band microwave chips is of great significance to radar systems.The switching power chip is a chip that integrates the power amplifier and the switch,and is the key component of the radio frequency transceiver（T/R）front end.Compared with the traditional T/R discrete switch chip and power amplifier chip scheme,the integrated chip is more conducive to the miniaturization of the RF front end,and reduces the micro-assembly process to improve the T/R assembly efficiency and system reliability,which is of great significance to military electronic equipment.Based on the 0.15μm SiC-based GaN process,this thesis studies the X-band switching power chip,focusing on the excessive insertion loss and mismatch of the switch and power amplifier output network,and proposes a method for the fusion design of switching and power amplifier output matching network,the main work is as follows:1.In view of the demand of switching power chip for low insertion loss,high power capacity（greater than 10W）switch,a single-pole double-throw（SPDT）switch chip is designed by combining multiple series and parallel switching transistors,the chip area is1.6×0.7mm²,the simulation results show that the switch has a power processing capability of 20W,the insertion loss is less than 0.7d B in the full frequency band range of 8～12GHz,and the isolation is greater than 29d B.2.In view of the demand of switching power chip for broadband and high-efficiency power amplifier,a power amplifier with an area of 3.5×2.2 mm² is designed by adopting multi-stage amplification and multi-channel power synthesis reactance matching method,and the simulation results show that the power amplifier has a small signal gain greater than 33.5 d B in the range of 8～12 GHz,an input return loss S11 is less than-15 d B,the output power Pout is greater than 41.5d Bm,the power additional efficiency PAE is greater than 38%,and the power gain is greater than 21d B.3.Aiming at the port impedance mismatch problem of traditional cascaded design switching power chips,a design method is proposed to replace the matching components in the power amplifier output matching network by using the equivalent components of the switch,so as to realize the integrated integration of the switch of the transmission branch and the power amplifier output matching network.This method eliminates impedance mismatches introduced by cascading and reduces the overall insertion loss of the switch and output matching network.The simulation results show that the network insertion loss of the fusion design is reduced by more than 0.1 d B in the X-band full frequency band compared with the cascade method.The continuous wave test results show that the designed switching power chip has a small signal gain of more than 32 d B and an S₁₁ below-10 d B in the range of 8～12 GHz,a saturated output power greater than40 d Bm,and a power additional efficiency（PAE）higher than 30%.The receive branch switch has insertion loss within 1.7 d B and isolation greater than 35 d B.