Analysis And Design Of Pulsed High Power Amplifier Based On GaN HEMT

In recent years,with the rapid development of wireless communications and aerospace systems,the solid state power amplifiers have been one of the most important components in the field of radar transmitters,wireless communications and electronic countermeasures.The high power,small size and high efficiency of the power amplifier have become the current research trends.Compared with the continuous-wave power amplifier,the pulse power amplifier can effectively improve the efficiency of the power amplifier and reduce the cooling requirements of the system,so the pulse power amplifier has been widely used in pulse radar and wireless communication transmitters etc.This thesis is focused on the design of a high-power pulse power amplifier based on the GaN HEMT devices and the main work can be summarized as follows.Firstly,the X-band high power amplification link is designed,and the overall design scheme,device selection,bias circuit,matching circuit and cavity design are all analyzed in details.The simulation software ADS is used to simulate and optimize the RF circuit.The simulation software HFSS is used to simulate the self-resonant frequency of the cavity.Finally,the final layout and cavity structure are drawn by Auto CAD and Solidworks.Secondly,according to the demand of power amplifier link,the drain-pulse modulation is chosen as the modulation mode of our pulse power amplifier.Furthermore,the factors affecting the time-domain parameters of pulse waveform are further anlyzed,and the pulse modulation voltage is optimized to ensure rapid rising and falling edge,as well steady voltage in the pulse state.At the same time,a negative gate voltage supply circuit and a protection circuit are designed to meet the voltage requirements of the power amplification link.Finally,the layout of the power supply circuit is completed by Altium Designer.Finally,a VB-based control program has been used to debug and test the power supply circuit and RF link,which can efficiently control all measuring instruments,and the communication between the software control interface and each measuring instrument is realized by the virtual software structure VISA.Due to the time limatation,only the driver-level PA was tested.From the measured results of the pulse high power amplifier described in this paper,at the center frequency f0GHz(bandwith:600MHz)and under the 1ms pulse period and 0.1%?1%of duty cycle,the high power amplifier can deliever more than 250W pulse output power,the gain is more than 58dB,and the PAE is beyond 30%from the frequency band.