Meeting the demand for ultra-high data-rate wireless communication

The exponential growth in data traffic and the need for high data rates in wireless communication systems require new technological solutions. For his thesis Piyush Kaul explored the challenges of packaging and integrating integrated circuits (ICs) with antennas and waveguides at millimeter-wave (mm-Wave) frequencies. By addressing these challenges, a new method for integrating ICs into metal waveguides was developed. The research introduces an active waveguide unit that combines electromagnetic and circuit design to integrate a power amplifier IC into a metal waveguide. A key innovation is the development of a contactless IC-to-waveguide transition, which reduces loss compared to traditional interconnect technologies. This is crucial for creating active antenna arrays used in high-speed backhaul systems. The thesis also addresses manufacturing and packaging issues, providing a comprehensive approach to designing high-performance mm-wave systems.

As more and more devices connect to the wireless network, more channel bandwidth (a.k.a radio spectrum allocation) is required to maintain higher data rates and network reliability. The radio spectrum is a finite resource governed by regulations to ensure sufficient spectrum for the most needed services, minimize national and international interference, and boost spectrum efficiency through, e.g., spectrum reuse. The backhaul network forms the backbone of the wireless infrastructure as it ensures high throughput and a reliable network to support connected mobile devices. Globally, the number of mobile devices connected to the network will approach 9 billion by 2025, and today, there are already 4 million microwave backhaul hops in operation. The growth in mobile data devices is continuing, straining the channel capacity of the backhaul network, which could impact the user service quality. Therefore, microwave backhauling is essential in providing overall energy efficiency and wireless link quality to support the increase in mobile devices. Backhaul systems are evolving to satisfy the rapidly rising channel capacity demands. The millimeter-wave (mm-Wave) spectrum (30-300 GHz) is critical in future innovations, such as next-generation wireless communications with enhanced capacity toward and beyond 100 Gbps data rate, particularly in point-to-point backhaul connections.

 Enhancing mm-Wave wireless integration

The research in this thesis introduces a new approach to developing ultra-high data-rate wireless communication links, specifically in the millimeter-wave (mm-Wave) frequency bands. To facilitate these wireless links, this research introduces the requirements of modern wireless systems and motivates the development of a microwave backhaul system at mm-Wave frequencies. The research proposes a novel integration and packaging method at mm-Wave frequencies to design and optimize electronics and antennas jointly. This method addresses several issues in conventional packaging and integration concepts, such as higher loss due to additional packaging steps, sensitivity to manufacturing tolerances at mm-Wave frequencies, and other effects. The proposed method utilizes a contactless connection based on electromagnetic coupling between electronics and waveguides. This connection reduces loss, alleviates tolerance uncertainties associated with integration and packaging, and can potentially improve bandwidth and system gain.

Developing advanced mm-Wave transmitters

This research envisioned a new transmitter front-end comprising a power amplifier and an antenna, and explores several semiconductor technologies to develop a wireless point-to-point communication system for future backhaul applications at mm-Wave frequencies. To facilitate the development of this new transmitter, the research emphasized the understanding of challenges in packaging, integration, and interfacing of electronics and antennas at mm-Wave frequencies. This understanding led to the development of a new methodology and a prototype based on a contactless connection for packaging and integrating electronics and waveguides/antennas.

The PhD research was conducted in the Integrated Circuits group within the Department of Electrical Engineering at TU/e. The project belongs to the research line of development of high-speed wireless systems to enable the next generation of communication systems. Primarily, this research focuses on the packaging and integrating electronics and antennas at millimeter-wave frequencies. It was financed by Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO).

Title of PhD thesis: Waveguide-Integrated Multi-channel Power Amplifiers at E-Band. Supervisors: Prof. Marion Matters-Kammerer, and Dr. Rob Maaskant.