The evolution of communication started in the early 1900s, and its commercialization slowly widened from single point-to-point communication to broadcasting systems. Later, the era of wireless communication began with far more applications.

In modern communication, the usage of cellular networks has become part of life, with exponentially increasing local and personal area networks. Modern wireless communication systems increase productivity, creativity, and innovative business. Semiconductor devices are foundational to the development and implementation of emerging wireless technologies.

What is ultra-wideband communication?

Ultra-wideband (UWB) is a revolutionary approach to wireless communication that enables high-speed data transfer. It can operate on a wide frequency spectrum, typically between 3.1-10.6 GHz. This enabled the use and marketing of products that incorporate UWB technology.

It transmits and receives pulse-based waveforms compressed in time rather than sinusoidal waveforms compressed in frequency. This enables the successful transmission of very low power spectral density. The equivalence of a narrowband pulse in the time domain to a signal of very wide bandwidth in the frequency domain is illustrated in Fig. 1.

The UWB spectral mask allows a spectral density of -41.3 dBm/MHz throughout the UWB frequency band. Operation at such a wide bandwidth entails lower power, which enables peaceful coexistence with narrowband systems. The FCC’s power requirement of –41.3 dBm/MHz is equal to 75 nanowatts/MHz for UWB systems.

Fig. 1: The equivalence of a pulse-based waveform in the frequency domain. Source: Rakesh Kumar, Ph.D.

Such a power restriction allows UWB systems to reside below the noise floor of a typical narrowband receiver, as depicted in Fig. 2. It enables UWB signals to coexist with current radio services with minimal or no interference.

Fig. 2 Coexistence of UWB signals with narrowband and wideband signals. Source: Rakesh Kumar, Ph.D.

Role of Semiconductor Devices in Ultra-Wideband Technology

UWB technology relies on generating very short pulses (in the nanosecond range) to transmit data over a wide frequency spectrum. Semiconductor devices such as high-speed transistors and integrated circuits are essential for creating these pulses with the required precision and timing. Semiconductors are used in the modulation and demodulation processes, converting data into UWB signals and vice versa. Complex signal-processing tasks are involved in this, which semiconductor-based components can handle effectively.

Semiconductor devices are fundamental to the successful deployment and operation of UWB technology. They enable the precise generation, processing, and management of UWB signals, ensuring high performance, low power consumption, and secure communications across a wide range of applications.

What are millimeter and sub-millimeter wave communications?

The important requirements when 5G millimeter-wave was introduced were a short latency and wide bandwidth to cover static, dynamic, and high-speed mobile applications.

The available unregulated, unlicensed millimeter-wave spectrum has a very large unutilized bandwidth with higher flexibility. More users and a large number of devices can be accommodated with a 10 to 100 times higher data rate. Since the advantages of millimeter wave frequency bands are greater, a great deal of interest has been generated in society.

The International Telecommunications Union (ITU) describes the millimeter-wave band as having a frequency range of 30 GHz to 300 GHz and a wavelength range of 1 mm to 10 mm. Similarly, the sub-millimeter band of frequency lies between 300 GHz and 3 THz.

The low-cost devices placed everywhere on the roads and in public places provide connectivity and access to almost all real-time data and updates. Seamless access to information will replace bulky memory devices and hard drives. Beam-forming, high-gain directional antennas can increase the range of communication.

Applications

The millimeter and sub-millimeter wave communication spectrum has a wide variety of applications in home and office automation systems, vehicular automation systems, traffic monitoring and vehicle tracking applications, civilian surveillance, cellular and personal mobile systems, aerospace and satellite applications, medical imaging and remote health care monitoring systems, and commercial sectors.

Cellular and personal mobile communication is the first and main reason for the evolution of the 5G and 6G systems. The large bandwidth characteristics of millimeter waves enable them to offer high-resolution video streaming for medical and civilian applications.

Challenges

The millimeter and sub-millimeter waves are largely affected by the atmosphere. Water vapor and oxygen present in the atmosphere interfere with these electromagnetic waves and attenuate the signal. Due to this attenuation, millimeter-wave communication is mainly limited to short-distance communication.

The short-range communication characteristics of millimeter-wave exhibit it as a suitable candidate for frequency reuse, thereby increasing the overall capacity. A number of users/devices can be accommodated on the wireless network. Picocell and femtocell concepts are used to increase capacity by involving frequency reuse and reducing the cost of operation.

Many technical hurdles, such as transceiver modeling, suitable electromagnetic sources, and efficient antennas, are involved in the development of the millimeter-wave communication system. Hence, much research is being done to answer these challenges. For long-distance communication systems, array antennas and repeaters are utilized. Beam-forming methods can increase the range by generating directional beams.

Role of Semiconductor Devices in Millimeter and Submillimeter Wave Communication

Semiconductor devices, such as oscillators and mixers, are essential for generating and converting high-frequency signals. Materials like GaAs, Gallium Nitride (GaN), and Silicon Germanium (SiGe) are preferred for mmWave applications due to their superior electron mobility and thermal properties compared to silicon.

Complementary metal-oxide-semiconductor (CMOS) technology is increasingly being adapted for mmWave applications. Semiconductor technologies enable the design of compact and efficient antenna arrays for mmWave communications. Semiconductor-based phased array antennas allow for dynamic beam steering.

To conclude, semiconductors enable the generation, amplification, processing, and transmission of high-frequency signals while also addressing challenges related to integration, thermal management, and signal propagation. As these technologies continue to evolve, the role of semiconductors will remain critical in driving innovation and enabling new applications in communications, radar, sensing, and beyond.

Summarizing the Key Points

●The interest in wireless communication has stepped up to the next level with the desire for a high data rate with a large bandwidth, low latency, and seamless connectivity.

●The low power specifications of UWB signals present a variety of opportunities and challenges to designers in a wide variety of fields, including RF and circuit design, communication system design, and antenna design.

●Millimeter-wave and sub-millimeter-wave communication systems were employed to meet the demands of modern communication systems.

●Semiconductor devices provide accurate design specifications and integration of IoT-based compact communication systems for various applications.