Efficient Terahertz Transmitters and Receivers in Silicon for Broadband Sensing and High-Speed Wireless Communication
With the emergence of new IOT and mobile applications, there has been an ever-increasing demand for high-data-rate wireless communication and high-resolution sensing. Researchers have put an extensive e ort to push the operating frequency of the communication and sensing systems. Sub-Terahertz (Sub-THz) band offers a wide unlicensed bandwidth that plays a critical role in the realization of high-speed wireless communication links. In addition, THz waves benefit from short wavelengths putting them at advantage compared to lower frequency bands for sensing and short-range high-resolution radars. Considering that current commercial THz systems are costly and bulky, developing these systems in standard silicon technologies is vital to lower the cost. In addition, this enables the integration of THz systems with other circuit blocks to implement a compact solution. THz generation in standard silicon technologies faces various challenges, including the limited speed of transistors. Since conventional techniques in the RF domain are not practical in the THz band, researchers have proposed new techniques to tackle the limitations of THz generation in silicon. Despite recent advancements, state-of-the-art THz systems still suffer from lower efficiency and low radiated power.
This study proposes a novel technique based on PIN diode reverse recovery to improve the power, bandwidth, and efficiency of the generated THz waves. Using the concept of reverse recovery, a PIN-diode-based pulse radiator is introduced that generates pulses with 1.7-ps Full Width at Half Maximum (FWHM). In the frequency domain, the generated pulses correspond to a frequency comb. The tones of the frequency comb are received using a harmonic mixer in the frequency range 220-1125 GHz. On the receiver side, a low-power heterodyne frequency comb receiver using Schottky Barrier Diode (SBD) is demonstrated.The receiver is used in conjunction with the broadband pulse radiator to implement a dual-comb spectroscopy system operating up to 550 GHz. By extending the idea of PIN reverse recovery into Continuous-Wave (CW) domain, a PIN diode-based CW 2�3 array source is designed that radiates at 430 GHz with 18.1-dBm Effective Isotropic Radiated Power (EIRP). Finally, the custom-built THz chips are employed for different applications, including micro-Doppler sensing of sound vibrations, long-distance THz communication, plasma physics characterization, imaging, and gas spectroscopy. My research on THz circuit design and techniques has resulted in innovations and advancements in the THz field by introducing new techniques for broadband efficient THz generation in low-cost silicon technologies. The proposed techniques pave the way for utilizing THz systems for different applications in applied physics, healthcare, and networks.