Tham khảo tài liệu 'sustainable energy harvesting technologies past present and future part 14', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Design Issues in Radio Frequency Energy Harvesting System 249 Published works have demonstrated the need for a DC-to-DC boost converter placed between the rectifying antenna circuit rectenna and the storage device. Recent efforts have demonstrated that a 40mV rectenna output DC voltage could be boosted to V to trickle charge some battery. A Coilcraft transformer with turns ratio Ns Np equal to 100 was used in the boost converter circuit. An IC chip leading manufacturer Linear Technology Corp. LT Journal 2010 has released a linear DC-to-DC boost regulator IC chip capable of boosting an input DC voltage as low as 20 mV and supplying a number of possible outputs specifically suited for energy harvesting applications. While this IC is a great milestone readers and researchers need to understand the techniques to achieve such ICs and also the limitations that apply. In the following sub section we will describe the methods toward designing a DC-DC boost converter suitable for micropower RF energy harvesting. In the design we will attempt to clarify the parameters that affect the DC-DC conversion efficiency. For this design Envelope simulation in Agilents s ADS is used. This simulation technique is the most efficient for the integrated rectenna and DC-DC boost converter circuits. DC-DC boost converter design theory and operation The DC-DC boost converter design theory and actual implementation are presented in this section. The inequality Vin Vout defines the boost operation. In this Chapter our boost converter concept is illustrated in Fig. 20. A small voltage Vin is presented at the input of the boost converter inductive pump which as a result generates some output voltage Vout. The output voltage is feedback to provide power for the oscillator. The oscillator generates a square wave Fosc that is used for gate signalling at the N-MOSFET switch. Fig. 20. Boost converter concept. The drain signal of the N-MOSFET is used as the switch node voltage Vsn at the .
