High-Gain and High-Efficiency Sub-Terahertz Antenna-on-Chip With Microbumps for Highly-Integrated Systems

This article presents a novel high-gain antenna-on-chip (AoC) solution for the sub-terahertz band using a standard semiconductor and packaging process. The novel AoC is realized by bonding on a usual AoC in a semiconductor technology with a microbump in a flip-chip technology. As a result, an additional radiation mode can be activated, leading to increased radiation efficiency and gain. Both usual and novel AoCs were designed in the dipole-type antenna configuration for the band of 300 GHz. The usual AoC was fabricated using a $0.13 \, \mu \text{m}$ silicon-germanium (SiGe) technology, while the novel AoC was fabricated using the same $0.13 \, \mu \text{m}$ SiGe technology and the standard flip-chip technology. The usual and novel AoCs have the same die area of $2 \times 2$ mm2. Compared with the usual AoC, the novel AoC has demonstrated the enhancement of all performance parameters. The radiation efficiency, peak realized gain, and impedance bandwidth have been improved significantly, rising from 15.9% to 41.1%, 1.91 to 8.67 dBi, and 15.6 to 39.6 GHz, respectively. Hence, it is believed that the novel AoC solution is particularly suitable for highly integrated sub-terahertz systems.

I. Introduction

The frequency range, from 0.3 to 3 terahertz (THz), has been recognized as a critical spectrum range for a variety of applications including security screening [1], medical imaging [2], radars [3], biological and material analysis [4], etc. It is also an especially appealing spectrum for next-generation wireless communication [5]. However, the high cost and low degree of integration of the III-V devices required for these systems limit their widespread usage. The advancements in the high-frequency capability of CMOS have made it possible to consider CMOS as a lower-cost alternative for implementing systems that can significantly expand the spectrum’s utilization [6].