# Dual-Band Rectifier Circuit Design for IoT Communication in 5G Systems
## 1 Introduction  
The Fourth Industrial Revolution changed the industry model by applying digitalization to old-style factories. This revolution is known as \"Industry 4.0\". The 4.0 attribute focuses on the Internet of Things (IoT) applied to industrial systems [1]. The IoT is a system in which different \"things\", such as people, animals, objects, computing devices, or digital machines, connect to each other and are capable of transferring data over a network without requiring any interaction between humans or humans and computers. A \"thing\" in the IoT (Internet of Things) could be an animal on a farm with a biochip transponder, a human with a heart implantable device, a car that has built-in sensors to alert the driver when something goes wrong with his vehicle, or any other natural or man-made object that can take an IP (Internet Protocol) address and can transfer data via the Internet. More and more organizations in many industrial units are using the Internet of Things to work more efficiently and more professionally, to understand their customers better, enhance customer services, improve decision making, and finally increase the value of their business. Hence, nowadays, the Internet of Things is one of the most important technologies, and it will continue to grow as more and more industries and businesses understand the potential of connected devices to keep them competitive [2; 3]. According to the [4; 5], there is an unprecedented increase at a rate of over 50% per year of wireless data traffic for each user. This is expected to accelerate over the next 10 years with the frequent use of video and the rise of the IoT. To address this phenomenon, the wireless industry is moving towards 5G cellular technology. With a possible peak speed of 20 Gbps and minimal latency (compared to 4G peak speed of 1 Gbps), 5G technology can enhance the performance of commercial and industrialapplications as well as other digital experiences, such as online gaming and teleconferencing. While earlier generations, such as 4G, were more concerned with providing connectivity, 5G virtualized networks take connectivity to the next level, bringing linked benefits from the cloud to clients [6]. Since the establishment of the fifth-generation (5G) cellular network, substantial new technological innovations have brought cutting-edge applications and services [7; 8] to current cellular and mobile networks [9; 10; 11; 12; 13; 14; 15]. Scientists generally agree that the IoT era can significantly contribute to the current need to transition to green energy. With the evolution of electronic devices and the increase in energy requirements, the capacity to collect RF energy from dedicated or ambient sources could be used to charge low-power devices continuously and, over time, eliminate the need for batteries [16; 17; 18]. Ambient RF energy harvesting is always available as a free energy source and is omnidirectional [19]. However, its primary disadvantage is its low power. The combination of an antenna and a rectifier creates a system called a rectenna [20]. Figure 1 depicts a classic RF energy harvesting system [21] that contains a transmission antenna and a rectenna (receiving antenna, an impedance matching network (IMN), a rectifier, and a DC-DC converter). RF signals are collected from the antenna, and then the rectifier converts these signals into DC voltage. The impedance-matching network (IMN) regulates the impedance between the antenna and the rectifier. The DC-DC converter boosts and stabilizes the output of the rectifier [22]. The rectifier is the most important part of the rectenna system, which significantly affects the system's efficiency [23]. The need for a rectifier circuit in autonomous systems is critical [24], especially in places with size and weight limits. There is a need for rectifiers that can transfer energy in many systems with minimum losses. In addition to that, the design of such a circuit must be very compact. There are a vast number of applications of such circuits in an IoT network.