Research On High Efficiency And Linearization Of Microwave Power Amplifier

Microwave power amplifier is one of the most critical component in wireless communication system.With the rapid development of wireless communication systems today,their requirements for the efficiency,bandwidth,and linearity of microwave power amplifiers are increasing.This dissertation has conducted in-depth research on the above issues.The research content is as follows.1.Introducing the types of high-efficiency power amplifiers,and on this basis,in order to adapt to today's broadband wireless communications,proposing the basic theory of high-efficiency power amplifiers that increase the phase-shift parameters of the mixed continuous inverse class.Solving the wide-band high-efficiency fundamental and harmonic impedance solution space of the power amplifier on the smith circle diagram.In the space of this impedance solution,the low-pass matching theory is adopted,and the input and output of the power amplifier are designed using the source-pull and load-pull techniques.The matching circuit allows the input impedance of the current source plane of the power amplifier tube to fall within the impedance solution space,thereby completing the design of a broadband high-efficiency power amplifier.This paper designs a broadband high-efficiency power amplifier operating at 2-3GHz.After testing,the drain efficiency is 67.5%-77.8%,the saturation output power is 40.2-42.4W,and the saturation power gain is 10.2-12.4dB.2.The Doherty power amplifier is studied for the non-constant envelope signal modulation method used for wireless base stations.The non-constant envelope signal modulation method causes the power amplifier not always operating at saturated output power which shows high efficiency,but will partially work at the back-off power,resulting in efficiency reducing.On the other hand,the bandwidth,efficiency and fallback efficiency of the Doherty power amplifier were studied.By removing the one-quarter wavelength impedance conversion line which limiting bandwidth and replacing the synthetic network with a wide-band stepped impedance conversion line,the back-off efficiency of the broadband Doherty power amplifier is effectively improved.Finally,a Doherty power amplifier with a working frequency band of 1.8-2.8GHz was designed.After testing,the saturation power is 43.4-44.6d Bm.The drain efficiency here is 55.8-71.3%,and the drain efficiency of 6 dB is greater than the drain efficiency.45.1%,saturation gain greater than 9.4dB.3.Based on the reflection-type analog predistortion theory,the linearizer is designed and a Ku-band reflection-type analog predistortive linearizer is designed using a Schottky diode and a 3dB bridge.After ADS simulation and optimization,at the center frequency of 14 GHz,by changing the bias voltage,the maximum gain expansion amplitude can reach 5.2d B,the maximum amplitude of phase compression can be achieved by 33.2with good nonlinear characteristics.