Research On AlGaN/GaN Hemt Microwave Power Characteristics And The Internal Matching Technology

In recent years, the third-generation semiconductor material GaN with advantages of wide bandgap, high electron saturated velocity, high critical breakdown field and high thermal conductivity, is becoming the most attractive one of new type semiconductor materials. Various studies show that high-power internal matching GaN HEMT , because of its small size, light weight, high output power, high Operating temperature, in all types of communication, radar and navigation equipment ,have been widely applied in the aviation, aerospace, phased array radar, and will have greater prospect. Basing on above background, this paper advised to study GaN HEMT microwave power characteristics and to develop independently high-power internal matching GaN HEMT.DC and microwave power performance of self-developed GaN HEMT of 2mm gate-width was studied. Study results showed that the GaN HEMT current collapse is less than 15 percent. Saturation currents can reach 1000 mA/mm. The transconductance of 240 mS/mm. Cut-off frequency can reach 40 GHz. The maximum output power is above 10W, power gain is higher than 6dB, and power-added efficiency is higher than 36%.By Curtice cubic model, Large signal model has been built for self-developed GaN HEMT of 2mm gate-width. After measuring accurately I-V and S-parameter for modeling, the parasitic parameters and parameters of I-V, Cgs and Cgd model were extracted. The Certification proves that the model can be used for computer simulation. At Vds = 28V, Vgs = 3.6V, the input impedance and the output impedance are as follows: (14.2-j8.3) ? and (5.2-j4.4) ?. Basing on characteristics of output-power and impedance of self-developed GaN HEMTof 2mm gate-width, the internal matching circuit and Splitters have been designed, and package and microwave power testing have been made. According to Wilkinson splitters, a one-to-four splitter has been designed. Through T-section impedance matching network, the gate connected whit splitter, and drain directly connected with splitter. Computer simulation and optimization has been done for the circuit by ADS, and ultimately the parameters of components in the circuit were determined. After the package device has been accomplished, microwave power testing has been made. Results show that the X-band output power is above 30W, at this time gain of 6.8dB, power-added efficiency of 38.2%.