Technique Review for Differential Drive Crossing Coupling Rectifier in RF Energy Harvester

This paper presents a comprehensive technique review for CCDD rectifier. It includes the challenges for the design of RF-to-DC rectifier and techniques for the efficiency improvement by controlling the gates and bodies of MOS in CCDD rectifier. The comparison of different techniques for efficiency improvement is concluded. The idea for novel CCDD is discussed and simple simulation result is shown in this paper. Introduction Over the past decades, low power design has attracted massive researches to push integrated system to consume as less as power with proper trade-off between parameters. Many low power and low voltage circuits have been reported [1]. However, it is still challenging to maintain these circuits working more than ten years without battery. Though integration has massively been increased driven by Moore’s law and power consumption has aggressively decreased, battery capability has not kept the pace of industry’s development. This trend has severely constrained the deployment of IoT. As the network of IoT requires massive nodes, about several millions, the battery replacement extremely increases the management cost. Figure 1. Main blocks for RF energy harvesting system. Energy harvesting technology is emerging as an excellent candidate to achieve self-sustainable nodes for IoT applications [2]. It has attracted intensive researches among academics. Although wireless energy among the free space features the minimal energy density due to the transmission loss among the above energy sources, RF energy harvesting attracts the researchers’ interests for its potential feasibility and compatibility with RF transceiver as antenna can both achieve signal receiving/transmitting and energy converting, so no extra energy converter component is required. As shown in Fig. 1, a simplified system blocks for RF energy harvesting constitutes with antenna, RF-to-DC rectifier and Power management unit (PMU). Antenna is used to receive the ambient RF energy in open air. RF-to-DC rectifier achieves to obtain the required DC energy. PMU is used to dynamically control the received energy. And high efficiency of RF-to-DC rectifier plays the most important role in RF energy harvesting system. As shown in Fig. 2, RF-to-DC rectifier can be categorized into two branches: single rectifier (Fig. 2a) and CCDD rectifier (Fig. 2b). This paper only focuses on the efficiency improvement techniques for CCDD rectifier. The rest of this paper is organized as follows. In section 2, the challenge for rectifier design will be stated. In section 3, techniques for high efficiency by controlling the gate and body of differential drive crossing coupling rectifier are reviewed. Finally, section 4 concludes this paper.