Research On High Efficiency Rectifiers With Modulated Waveform For Simultaneous Wireless Information And Power Transmission Systems

Simultaneous Wireless Information and Power Transmission(SWIPT)technology,combing the Wireless Information Transmission and Wireless Power Transmission together,carries out the high-quality communication and power transfer by electromagnetic wave at the same time.It can be widely utilized in Wireless Sensor Networks(WSN),Internet of Things(Io T)and implant medical devices.The rectifier,converting the received microwave power into the direct power and supply it to the wireless devices,is the key component of a SWIPT system.By using the theoretical formula,simulation and experiment,the research and design of the rectifiers with different modulated waveforms for SWIPT are studied in this thesis.Four main works are included as follows.Firstly,the theoretical formula of the pulse wave rectification is derived,and verified by the simulations and experiments of the rectifier designed on the GCPW(Grounded Coplanar Waveguide)transmission line.It is found that the rectifying efficiency can maintain on a high level with different duty cycle by changing the load of the rectifier.When the pulse wave signal is 4 μs and the repetition period is 10 μs(duty cycle equals 0.4),the measured maximum efficiency is 75.4 % at 5.77 GHz carrier frequency with the mean input power of 19.2 d Bm.The experimental results under different duty cycle validates the conclusion derived from the formula.Secondly,the rectifier with the Amplitude Modulation(AM)waveform is studied.Theoretical formula of the rectification process of AM waveform is deduced,and the relationship among the amplitude modulation factor,the input power and the rectifying efficiency is summarized.For the proposed high-efficiency AM wave rectifier,the simulated maximum efficiency is 78.1 % at 5.8 GHz carrier frequency on the 15.7 d Bm input power with 0.2 amplitude modulation factor.The simulated results under different amplitude modulation factor validate the formula.Thirdly,the high efficiency rectifier with multisine waves is studied.Different types of the dc-pass filter are compared and simulated to choose the most moderate one for multisine signal rectification.Then the three tones rectifier with multisine waveform is designed.When the central frequency is 5.8 GHz with 50 MHz frequency spacing,the simulated maximum efficiency is 72.6 % at the input power of 15.7 d Bm.For the multisine signals with the same central frequency and input power,the rectifying efficiency decreases with the number of carrier waves increasing.Fourthly,the rectification with digital modulation wave is preliminarily studied by the experiments.A high efficiency continuous wave(CW)rectifier based on voltage double topology is designed,which is suitable for a high input power.The maximum measured efficiency is 78.7 %,68.6 % and 66.3 % when the input waveform is CW,64QAM(64 Quadrature Amplitude Modulation)and QPSK(Quadrature Phase Shift Keying)at 2.59 GHz carrier frequency on the 25.6 d Bm input power.A SWIPT system which includes the designed rectifier is proposed.When the carrier frequency is 2.58 GHz and the input power is 26.9 d Bm,the maximum measured efficiencies for the CW input waveform and QPSK signal are 74.9 % and 67%,respectively.Meanwhile,the received signal remains unchanged comparing with the transmitted one.