Abstract
Wireless communication has undergone a significant evolution from 1G to 5G, with diverse applications targeting different areas, such as low-power Internet of Things (IoT) and high-speed data communication. It is expected that the next generation of communication will be a coexistence of these areas and possibly more. The IoT market is predicted to exceed 25 billion devices by 2030, highlighting its immense potential for growth in the future. One of the major application areas in 5G IoT is Massive Machine-Type Communications (mMTC), which targets low-power, low-data-rate, and wide-coverage applications, such as smart agriculture and industrial monitoring. However, with the massive deployment of IoT nodes in these applications, the cost of replacing batteries for all IoT nodes becomes unacceptable. To address this issue, Wake-up receivers (WuRx) can be integrated into the IoT node to allow it to start working only when the wake-up signal is detected. Since most event-driven applications, such as temperature or moisture monitoring for agriculture, are only active once every few hours, the use of wake-up receivers enables IoT nodes to save a significant amount of power and extend their battery life to several years.
Since the IoT node is in sleep mode most of the time, WuRx's power dominates the total power consumption. Thus reducing the WuRx's power to sub 10 µW is imperative for extending the battery lifetime. In the meantime, better sensitivity is necessary to extend the communication distance for wider area coverage and massive deployment. Heterodyne architecture typically presents a superior sensitivity due to the additional filtering at the intermediate frequency (IF) stage but at the cost of higher power consumption because of the local oscillator (LO) generation using phase-locked loops (PLL). As a result, PLL integration in the WuRxs needs to be low-power and low-phase-noise to not degrade the signal-to-noise Ratio (SNR) of the WuRx.
In addition, high-speed applications such as Virtual Reality (VR), autonomous driving, and cloud computing push for the next-generation wireless communication development beyond 100 GHz to acquire more bandwidth. However, the path loss increases quadratically with frequency, which demands higher output power to achieve the same communication distance as in 5G. Therefore, power amplifiers (PAs), critical blocks to amplify the signal to high power levels in the transmitter, require high output power and efficiency. The distributive active transformer (DAT)-based power combining technique is popular at low frequencies and offers good efficiency and impedance transformation to achieve high output power. The design challenges of DAT in F band (90 GHz to 140 GHz) power amplifiers are investigated.
This research presents design techniques to demonstrate that heterodyne architecture wake-up receivers with integrated PLL can achieve below -100 dBm sensitivity and excellent interference robustness with micro-watt-level power consumption, to extend the area coverage of outdoor battery-driven IoT devices. Additionally, the distributive active transformer power combining topology can achieve a compact core area, and a good balance between bandwidth and loss for the F band PA design, which extends the communication range for the next-generation wireless communication applications.
