Investigations On The Millimeter-Wave Broadband Radio System And Broadband High-efficiency Power Amplifier

With the development of the mobile communication and the popularization of wireless transferring service,the wireless system is hoped to offer higher transmission rate to meet the requirement of fast transmission of high-capacity data,such as high-definition video without compression,high-definition wireless display and so on.According to the plan,the next generation mobile communication system is required to offer 1000 times faster transmission rate than that of the current system.The next generation system needs wider operating bandwidth to reach the target,up to hundreds of MHz,even several GHz.Furthermore,the next wireless system needs higher efficiceny to realize energy saving.In order to follow the tendency of the development of future mobile communication,the research works on millimeter-wave broadband radio system and broadband high-efficiency power amplifier are carried out.The millimeter wave communication is paid attention widely and researched as the candidate project of the next generation wireless communication because of the sufficient spectrum resource in the millimeter-wave band.The millimeter-wave broadband radio system is researched and designed to support the study of millimeter wave communication technology.The influence on the system performance from the inband flatness is solved.Moreover,the substrate integrated waveguide(SIW)filter is studied in this paper to slove the problem of high insertion loss of general filters.The power amplifier(PA),as a key element in the radio system,cosuming most of the energy of the transmitter,has important influence on the power consumption index of the overall system.The PA is hoped to achieve high efficiency over a broad band,cover more communication standards to adapt the development of wireless communication in the future.In recent years,the broadband power amplifier has been being a hot topic in academia.The details are illustrated as follows:1)The SIW filter is the candidate for the design of millimeter wave system as its low insertion loss,easy integration with other plane circuits,etc.The transmission zeros(TZs)are often introduced near the passband to improve the selectivity of the filter.The cross-coupled SIW filter is studied,using the coupling between different cavities and the coupling between higher/lower modes in the same cavity.A SIW filter is designed with the center frequency of 28 GHz,and the bandwidth of 600 MHz.The filter has sharper transition performance as the introduction of TZs at 27 GHz and 29 GHz.In the upper frequency of the SIW filter,several undesired pass bands appear because of the higher-order resonant modes,thus restricting the bandwidth of the stopband.Two methods are proposed to suppress the high-order modes.One is to etch narrow slots on the metallic plate of cavities,the other is to use double coupling irises instead of single iris between two cavities.Both of them are discussed and analyzed detailed.A SIW filter is designed with the center frequency of 20 GHz.Due to the suppression of high-order modes,the first spurious appears at about 50 GHz,and the suppression in the stopband is better than 30 dB.The bandwidth of the stopband is broadened extremely.Some work has been published in the international conference 2016 IEEE International Symposium on Circuits and Systems(ISCAS2016)and some design is submitted to IET Electronics Letters.2)A Q-band millimeter wave transceiver is designed with the operation frequency of 44.82 GHz and the bandwidth of 500 MHz.The superheterodyne structure is adopted.The system is connected with the baseband hardware with single-ended I/Q interface,connected with the antenna with SIW transition.The immediate frequency(IF)is set as 3.78 GHz.In order to evaluate the performance of the system,the broadband modulation signals,]6QAM and QPSK,are used to test the transceiver in the wireless environment.The data rate of the signals is 400 Ms/s.The signals are transmitted by the transmitter,through 2-meter space attenuation,received and converted to baseband by the receiver.The demodulated baseband signals have the signal-to-noise ratio(SNR)of about 20 dB.The research has been published in the international conference 2016 International Conference on Microwave and Millimeter Wave Technology(ICMMT2016).3)The prototype system is developed to support the research of the China MMW high-speed communication standard "Q-LINKPAN".The transceiver uses the structure of two frequency conversions and real signal sampling at the baseband.The baseband hardware transmits or receives real signal at some carrier frequency,then the signal is converted to millimeter wave by two frequency conversions.The system supports 576-MHz bandwidth,with the millimeter center frequency of 42.795 GHz.The AD samples the signal at the carrier frequency of 1.44 GHz,with the sampling rate of 1.92 GHz in the receiver.The DA produces the signal at the carrier of 1.92 GHz,with the sampling rate of 2.64 GHz in the transmitter.The system uses the mode of TDD.A single-carrier 64QAM signal,with the data rate of 480 MHz,is used to test the single-channel performance of the system.The received signal has SNR of 28 dB after digital equalization.The system can achieve data transmission rate of 4095 Mbps under the mode of 2×4 MIMO.4)The voltage and current waveforms of the continuous inverse class F PA are studied and modified.The range of the third harmonic impedance is extended and the power amplifier has more flexible harmonic impedance requirements.A 2.1?2.4 GHz high-efficiency PA is designed and the impedance of its output matching network(MN)is compared with the theoretical one.The designed PA can maintain more than 71%drain efficiency across the bandwidth.The research has been published in Microwave Journal.5)The broadband matching problem in designing broadband PA is studied.The conventional simplified real frequency technique(SRFT)algorithm is modified and can be used to synthesize compact MN with the shorted-series stub for DC bias.A broadband high-efficiency PA is designed using the proposed algorithm,with the frequency range of 1.7?3.1 GHz.the PA achieves 68.07%-79.49%drain efficiency and 40.93 dBm-42.4 dBm output power.The fabricated PA has a small size due to the compact MNs.The research has been published in IEEE Microwave and Wireless Components Letters.