AC-coupled substrate-integrated waveguide slot antenna in CMOS for terahertz applications

Abstract

Substrate integrated waveguide (SIW) technology exhibits an emerging and very promising candidate for the development of circuits and components in the millimeter-wave region. As a part of the high-frequency wireless communication system, the on-chip antenna is playing an important role. However, designing an on-chip antenna presents significant challenges due to the design-rule restrictions posed by the foundries. Also, antenna performance degrades owing to the process limitation and the conventional structure. In this thesis, an on-chip SIW slot antenna has been designed in the TSMC 65-nm CMOS process to improve the radiation efficiency and to minimize the radiation leakage of the antenna. The antenna shows radiation efficiency of 35% and −10-dB bandwidth of 20 GHz at 410 GHz. However, characterizing on-chip antennas at this THz frequency range is difficult due to parasitic radiations from the measurement apparatus such as THz probes. One way to measure the antenna response is to integrate a detector circuit. Typically, a detector circuit needs RF and DC signal isolation. However, the SIW structure of the antenna is DC-shorted in the sidewall which poses a great challenge to building a detector circuit. Therefore, an AC-coupled SIW slot antenna has been presented by exploiting the antenna sidewall as a DC capacitor. Therefore, the SIW slot antenna including the DC capacitor can work well as expected. The designed AC-coupled SIW slot antenna integrated detector exhibits voltage responsivity of 316 V/W and 37 pW/Hz1/2 at 410 GHz.