Research On S-band GaN High Efficiency Internally Matched Power Amplifier Design Technology

Gallium nitride(GaN) as a new generation of semiconductor materials, has the advantages of a wide bandgap, high electron mobility, high saturated electron velocity and high breakdown electric field. All of these meet the requirements of high voltage, high current and high power density. It is very suitable for high power and high efficiency microwave power amplifier. Current radar communication systems demand for higher power and efficiency solid-state power amplifier. Internally matched microwave high power devices, as a class of solid state devices, because of small volume, light weight, difficulty of realization and relatively low cost, are very popular in all kinds of communication, radar and navigation markets. Therefore, on the basis of the GaN, internally matched microwave power devices are becoming a hot spot of research in recent years. Harmonic control, in recent years, as a kind of effective technology in improving microwave power amplifier efficiency, often has been found in microwave monolithic integrated circuit(MMIC) and microwave hybrid integrated circuit(MHIC). Due to space constraints in internally matched devices, complex harmonic control unit is difficult to match the environment. Therefore, this thesis will review on the principles and design methods of harmonic control power amplifier. According to the characteristics of GaN HEMT, the harmonic control method applied in GaN internally matched power amplifier is discussed. Main work and innovation are as follows.Based on the domestic GaN HEMT devices, the amplifier takes two signal paths in the form of structure. In the transistor input, according to the actual size and power amplifier structure, combined with a parallel R-C network and a series R-C network, both in different frequency bands to improve the stability, design a stability network which can realize unconditionally stable in the entire band and eliminate odd-mode oscillation across two signal paths. Through a power divider with impedance transformation function at the input and ouput terminals, the impedance matching network transformation ratio could be reduced. Combined with the harmonic control theory, matching networks with shunt capacitance on high dielectric constant substrate, series inductance by bonding wire, have been designed under the guide of second harmonic load-pull system. It meet the high efficiency working conditions. And through the analysis of time domain voltage and current waveforms, from the view of waveform engineering, the effectiveness of harmonic control method to design high efficiency amplifiers have been demonstrated. In the end, an S-band GaN high efficiency internally matched power amplifier has been fabricated.At the bias point VGS=-2.8V, VDS=28V, the simulation result shows that, within 2.7~3.5 GHz, input power Pin=37dBm, output power Pout>47dBm, Gain>10dB, power added efficiency PAE>68%. To the measured result, at 3.1 GHz, this microwave power amplifier demonstrates a small signal gain of 9.1dB, and Pin=44dBm, Pout=47.4dBm, Gain=3.4dB, DE(drain efficiency)=44.6%, PAE=24.3%.For the design of wide bandgap semiconductor high efficiency internally matched power amplifier, this paper has a practical significance.