Characteristic And Power Amplifier Investigation On Gan High Electron Mobility Transistor

The rapid development of the global wireless communication technologiesincreases the market demand for transceiver of a wireless communication system andgives higher performance requirements of the transceiver. In the entire wirelesscommunication system, the power amplifier is the critical components of thetransmitter, whose performances, such as bandwidth, output power, efficiency andworking temperature, severely affect the overall fuction of the system. The powerdevice is the most important and critical part of the power amplfier, such as the deviceof silicon-lateral deffusion metal oxide semiconductor, GaAs, InP and SiC, etc. Due tothe physical charactristics limitations of the materials themselves, they can not meetthe needs of the application, and the development of new materials using for powerdevices is extremely urgent. As the behalf of the third generation of semiconductormaterial, GaN, which is a wide-bandgap semiconductor material, become a hotresearch topic due to its excellent electrical and thermal properties. The advantageouscharacteristics of GaN HEMT are well known and documented. These include highbreakdown voltage, high current carrying capability, high power density and highfrequency of operation. These attributes make GaN HEMT well suited for present andfuture wireless communication systems. It is a cutting-edge research that is thephysical characteristics of the high electron mobility transistor of GaN and itsapplication in the power amplfier. The research has important value and practicalsignificance. The dissertation focuses on the research on the characteristics of highelecton mobility transistor using GaN and its application in power amplifer.To study the small signal model of GaN HEMT. A small-signal equivalent circuitmodel is proposed, and a direct extraction method with detailed parameter extractionprocess is given to extract the small signal parameters. The accuracy of the model isverified by the comparison of the simulated and measured S-parameter. A large-signalnonlinear model, whose DC model is improved by considering the impact of thegate-source voltage on the knee voltage, is established for GaN HEMT based onEEHEMT1(the ADS large-signal nonlinear model). The accuracy and usability of thelarge-signal nonlinear model is proved by the comparison of the simulated andmeasured data.A design procedure and implementation for a broadband balanced PA has beenpresented from several aspects; wideband matching, broadband couplers, bias circuit and thermal design. A wideband balanced PA is fabricated based on GaN HEMTdevices. Measured results are in agreement with design expectations showing highefficiency and large bandwidth. The excellent results obtained verify the correctnessof the design method.The effects of a transistor output capacitance is analyzed for performance of aClass-E power amplifier. The output capacitance of the transistor is found to destroythe ZCS and ZCDS conditions of a Class-E power amplifier. The increase of theoutput capacitor will cause the decline of the amplifier efficiency and output power.And the maximum operation frequency of the Class-E PA is found to be affected bythe transistor’s output capacitance. In order to eliminate the limitation on themaximum operation frequency caused by the transistor’s output capacitor, amulti-frequency inductance-compensation method is proposed to eliminate the impactof large output capacitance. The theoretical derivation is carried out in detail, and thecorrectness of the theoretical analysis is proved by simulation results.Two transmission-line compensation circuits is developed, considering theapplication of the multi-frequency inductance-compensation technology in themicrowave band, to effectively eliminate the limitation on the opertation frequency ofthe transistor output capacitance. Analytical expressions are derived to determine thevalues of the required circuit elements in detail. The proposed circuit has beensimulated and the predicted behavior is substantiated by measurements results. Basedon the theory developed, a class-E PA has been designed, fabricated and measured.The agreement between simulation and measured data, taken together with ease offabrication demonstrates the validity and advantage of the proposed capacitivecompensation network. The restriction on operating frequency imposed by thetransistor’s increased output capacitance is eliminated, and the comprehensiveperformance of the power amplifier is significantly improved.An inverse Class-E power amplifier with finite D.C. feed inductance is propesedand analyzed. A set of design equations are derived in order to obtain the values of thecircuit components and evaluate the major performance parameters. As analyticalsolutions of the resultant circuit equations are cumbersome, the performance of theproposed inverse class-E PA is analyzed using numerical simulations, tables, andgraphs. The advantages of an inverse Class-E amplifier are compared with otherclass-E PA. The proposed PA has been simulated and the predicted behavior has beensubstantiated by measurements. The agreement between simulation and measured data,demonstrates the validity of the proposed PA. In order to make it better in the microwave band applications, a transmission-line topology is proposed of theinverse class-E power maplifier. A3-GHz inverse class-E power amplifier instancehas been designed, fabricated and measured. Due to the effective harmonicsuppression, the using and compensation of the transisitor drain inductor and outputcapacitor, the output power and efficiency are effectively improved. Excellentmeasured results prove that the circuit technology can be widely used in the design ofthe microwave-band high-efficiency power amplifier.