# A 0.18 um CMOS Millimeter Wave Antenna-on-Chip with Artificial Magnetic Conductor Design
## 1 Introduction  
The increasing demand for wireless connections has led to data traffic congestion on the traditional microwave spectrum. To cope with such huge demand, the Third Generation Partner Program (3 GPP) expanded the frequency band of 5G new radio (5G NR) to FR1 (0.4 GHz-7.1 GHz) and FR2 (24.2 GHz-52.6 GHz) to achieve higher connectivity, a higher data rate, ultra-low latency, higher energy efficiency, and higher spectral efficiency to process these data and information [1, 2]. Under the network coverage of the fifth-generation mobile communication, billions of physical devices worldwide are connected to the Internet and transmit a large amount of data information through a network independent of human behavior [3, 4]. The Internet of Things has promoted the rapid growth of smart homes, smart cities, smart grids, industrial automation, health care, environment, and traffic monitoring. Even the sudden outbreak of the coronavirus epidemic did not show a downward trend in demand [5, 6, 7]. With the transformation of mobile communication networks, there is more and more research on the frequency bands of millimeter wave communication systems, including n257 (26.5 GHz-29.5 GHz), n258 (24.2 GHz-27.5 GHz), n259 (39.5 GHz-43.5 GHz), n260 (37 GHz-40 GHz), and n261 (27.5 GHz-28.3 GHz). The realization of high-performance, low-cost and low-power transceivers has become an important research topic [8]. At the same time, the 60 GHz and 77 GHz bands are also being studied in the fields of industry, science, medical treatment, and automotive radar [9]. In addition to the millimeter wave band, the terahertz above 100 GHz is also attracting attention. Technological progress has meant that the development of terahertz is also included in the possibility of future mobile networks [10]. The terahertz can be applied to physical systems such as autonomous driving vehicles, robot networks, and virtual reality or in intelligent sensing, imaging, defect detection, short-range wireless communication, and other applications [11]. In the past two decades, integrated circuits have made a breakthrough in growth because of advanced technology. Billions of transistors can be manufactured on a few square millimeters of a wafer, and the precision of manufacturing technology is becoming more and more mature [12]. As the high-frequency capability of chip antenna is improved through scaling, the complementary metal oxide semiconductor (CMOS) has become a feasible manufacturing method for chip antenna and can integrate a complete chip antenna system on a single chip through CMOS technology, further improving the competitiveness of the system [13; 14]. Compared with the traditional antenna system, the chip antenna system has higher bandwidth, better integration, and lower power consumption. In addition, as the most critical part of the system, the chip antenna eliminates the parasitic effect and uncertainty of the circuit caused by additional connections. The chip antenna can be directly connected to the circuit without an additional matching network, which provides more flexible design methods for designers and facilitates chip layout [15; 16]. In addition to the millimeter wave spectrum, CMOS technology is also considered a good choice for the terahertz because its scaling and low-cost technology also have characteristics of high-density integration and performance improvement like the millimeter wave system. For this reason, the chip antenna in the terahertz is also crucial to the terahertz system [17]. The progress of communication technology has brought great potential for the development of terahertz, which will be applied in medical imaging, astronomy, and other fields in the future [18]. In recent years, millimeter wave chips have been extensively studied. They have different orientations and implementation methods, such as miniaturization [19], resonance analysis [20; 21], integrated circuit design [22; 23], the introduction of AMCs [24; 25; 26], and integration with printed circuit boards [8; 27].