Power Combining Technology Based On Substrate Integrated Suspended Line

Recently,with the strong development of wireless communication technology towards miniaturization and low power consumption,the same requirements are made for wireless communication devices including the transmitter.The power amplifier is the high power consumption component in the transmitter.It is an important method to reduce the size and power consumption of a transceiver by finding out how to reduce the size,enhance integration and improve the efficiency of the power amplifier.In recent years,substrate integrated suspended line(SISL)with the property of multi-layer has attracted the study enthusiasm of researchers,because of its advantages like self-packaging and low loss.Therefore,based on the above advantages of SISL,the research of power combining technology is carried out in this dissertation,including how to reduce loss,reduce circuit size,achieve high integration and multi-function,etc.The main contents are as follows:1.The method to reduce the circuit size of power divider is proposed by increasing the coupling of coupled line to reduce the electrical length and by bending the two output paths into the regular octagonal spiral shape to improve the circuit area utilization.Based on this topology,a power divider working at 2.5 GHz is designed,the total electrical length is decreased by 37%as compared with the traditional Wilkinson power divider.The measured effective circuit size is 0.1λ_g×0.1λ_g,whereλ_g is the guided wavelength at the center frequency 2.5 GHz.2.SISL based dual-layer inter-digital capacitor with high capacitance density and SISL based dual-layer spiral inductor with high inductance density and high Q-factor is proposed to reduce circuit size and loss.Filter function integration is realized by using the two quasi-lumped elements to construct LC resonate circuits.Based on this method,a bandpass filtering power divider,a lowpass filtering power divider,and a bandpass filtering power amplifier are designed.The bandpass filtering power divider works at0.95 GHz,and the measured effective circuit size is only 0.085λ_g×0.071λ_g,whereλ_gis the guided wavelength at the center frequency 0.95 GHz.The lowpass filtering power divider works at 0.9 GHz,and the measured effective circuit size is 0.05λ_g×0.08λ_g,whereλ_g is the guided wavelength at the center frequency 0.9 GHz.Both of the two power dividers exhibit good filtering responses and small circuit sizes.The bandpass filtering power amplifier works at 0.9 GHz,and the 40 d B rectangular coefficient is3.45.A high harmonic suppression level with an attenuation level of 40 d Bc is realized,and the measured effective circuit size is only 0.12λ_g×0.07λ_g,whereλ_g is the guided wavelength at the center frequency 0.9 GHz.To our best knowledge,it is the smallest bandpass filtering power amplifier based on the PCB process.3.Two dual-band power dividers that based on coupled lines and with tunable frequency ratio are proposed.Both of the two power dividers work at WLAN dual-band frequency.For the first power divider,a transmission line and a coupled line are used to realize dual-band impedance transformation,and a SIR resonator is loaded at the input to generate a transmission zero between two passbands to improve the frequency selectivity.For the second power divider,a two-section cascaded coupled line is used to realize dual-band impedance transformation,and a coupled line is in series at the input to produce a transmission zero between two passbands to improve frequency selectivity and increase the bandwidth in the meantime.For both of the two power dividers,the frequency ratio can be adjusted by changing the coupling strength of the second coupled line of the dual-band impedance transformation networks.The dual-band bandwidth of the second power divider is nearly doubled compared with the first one.4.The circuit loss of power dividers or combiners and power amplifiers are reduced by cutting off the redundant substrate of SISL.The electromagnetic fields of SISL circuits are mainly distributed in lossless air,so it has a low dielectric loss.In this dissertation,the suspended substrate of the substrate integrated suspended line except for metal circuit covered and for supporting,other parts are all cut off,to make more electromagnetic fields distributed in lossless air,so the circuit loss of the power divider/combiner can be further reduced.5.The metal integrated and substrate integrated suspended line(MI-SISL)is firstly proposed to solve the dissipation problem of high power amplifier based on SISL.In this dissertation,the top and bottom substrate boards of traditional SISL are replaced by metal boards with high electrical and thermal conductivity.As compared with SISL,MI-SISL based power amplifier is easier to exchange heat with the outside world.