The Research Of Continuous Power Amplifiers

In order to meet the requirements of massive high-speed data transmission in wireless communication systems,the key equipment in communication system—power amplifier(PA),carries more and more expectations,including the requirements for highefficiency,wide working band,digitization and so on.The continuous PA mode has been the leading candidates for realizing high-efficiency,extending bandwidth and improving linearity.The research on the design space is beneficial to designing high-performance power amplifier.In this thesis,based on the basic continuous mode,the continuous model with better performance and adaptability for different application scenarios is derived.The main contents and innovation points of this thesis are summarized as follows:1.The typical modes of high-efficiency and broadband PAs are summarized,and their time-domain waveforms and design space are compared in this thesis.Based on the newly proposed the series continuous model,a novel hybrid continuous mode is proposed.Compared with the former,the latter’s current and voltage waveforms are reshaped and the impedance solutions space offers a greater freedom,which is good for designing output matching network(OMN).Based on the proposed mode,in this thesis,the method of designing a continuous power amplifier matching network with low-pass filter prototype is introduced in detail,including the ideal-network synthesis and implementation using transmission lines.Finally,based on the above analysis,a power amplifier working form 2.3 GHz to 3.9 GHz is designed.The measured drain efficiency is 57%-79% and the gain is greater than 9.8 dB,which is comparable with other continuous models.2.In this thesis,a hybrid continuous inverse mode with variable real part of optimal fundamental impedance is analyzed math mathematically.The hybrid continuous inverse mode contains the classical continuous inverse Class-F mode,the continuous inverse F mode with maximally flat current waveforms and the inverse Class-B to Class-J continuum mode and so on,which provides alternative design space for realizing the broadband high-efficiency PAs.And the performance of the mode is analyzed.And in the wide design space,the excellent performances are still sustained.And a highefficiency PA using the stepped-impedance microstrip-line bandpass-filter network is designed to verify this theory.Experimental results show that the saturation drain efficiency(DE)is over 70% from 3.2 to 3.7 GHz.For a 5 MHz two-tone signal,drain efficiency of 40.3%–48% is measured at a carrier-to-intermodulation ratio(C/I)of-30 dBc.3.The high-efficient working mechanism of continuous class models “waveform engineering” is analyzed and an extend class-B/J mode is presented in this thesis.The enhanced voltage waveform formulation,which gives multiple impedances solutions of the fundamental and harmonics for the target performance by adding the harmonic elements,has been described mathematically.Unlike conventional continuous Class-J mode,the real and imaginary parts of optimal fundamental and second-harmonic impedance of the new mode can vary on the smith chart.A high-efficiency PA from 2.85-4.25 GHz,based on the optimal impedance at package plane,is designed.The measurement results illustrate that the drain efficiency(DE)is 58%-78% and PAE is 54.5%–74% across the entire band.For a 5 MHz WCDMA signal with a peak-to-average ratio(PAR)of 8.6 dB,an adjacent channel leakage ratio(ACLR)of-31.5 to-38 dBc is measured at an average DE of 38%–48% when the output power(Pout)is 36 dBm from 2.85–4.25 GHz.4.The difficulties in designing continuous power amplifier with multi-octave working bands are analyzed.Based on the extended class-B/J model,a 0.7-3.6GHz highefficiency PA is designed to verify the theory.In the design process,the method for choosing optimal design space is discussed,and the best design space is adopted.The influence on efficiency when harmonic second harmonic and third harmonic mismatch is analyzed.Analysis results show that,in order to improve efficiency,second harmonic impedance is better to be right away from optimal impedance and third harmonics is better to approach the open point by the edge of Smith chart.By synthesizing the device output package parasitics and the matching networks,a compact 10 W PA with 47% higher PAE and 10.2–12.6 dB gain is designed.