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 <inline-formula> <tex-math notation="LaTeX">$0.13 \, \mu \text{m}$ </tex-math></inline-formula> silicon-germanium (SiGe) technology, while the novel AoC was fabricated using the same <inline-formula> <tex-math notation="LaTeX">$0.13 \, \mu \text{m}$ </tex-math></inline-formula> SiGe technology and the standard flip-chip technology. The usual and novel AoCs have the same die area of <inline-formula> <tex-math notation="LaTeX">$2 \times 2$ </tex-math></inline-formula> 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.