A Terahertz CMOS V-Shaped Patch Antenna with Defected Ground Structure

Abstract

In this paper, a V-shaped patch antenna with defected ground structure is proposed at terahertz to overcome the limited performance of a standard complementary metal-oxide semiconductor (CMOS) patch antenna consisting of several metal layers and very thin interdielectric layers. The proposed V-shaped patch with slots allows the increased radiation resistance and broadband performance. In addition, the patch resonating at different frequency from the V-shaped patch is stacked on the top to broaden the impedance-matching bandwidth. More importantly, the slots are formed in the ground plane, which is called the defected ground structure, to further increase the radiation resistance and thus improve the bandwidth and efficiency. It is verified from electromagnetic simulations that the leakage waves from the defected ground can enhance the antenna directivity and gain by coherently interfering with the topside radiation. The proposed on-chip antenna is fabricated using a standard 65 nm CMOS process. The on-wafer measurement shows very wide bandwidth in input reflection coefficient (<−10 dB), greater than 28.7% from 240 to >320 GHz. The measured peak gain was as high as 5.48 dBi at 295 GHz. To the best of the authors’ knowledge, these results belong to the best performance among the terahertz CMOS on-chip antennas without using additional components or processes such as dielectric resonators, lens, or substrate thinning.

A Broadband THz On-Chip Transition Using a Dipole Antenna with Integrated Balun

“…Recently, there has been extensive research on THz applications in various fields, such as high-speed communications, non-destructive inspections, spectroscopy, and medical imaging [2][3][4]. THz monolithic integrated circuits (TMICs), such as power amplifiers, multipliers, mixers, and antennas, have been successfully developed using advanced transistor technologies, such as a complementary metal oxide semiconductor (CMOS), gallium arsenide (GaAs) high-electron mobility transistors (HEMTs), and indium phosphide (InP) heterojunction bipolar transistors (HBTs) [5][6][7][8][9][10]. These semiconductor-based technologies allow the production of low-cost, compact, portable, and mass-producible THz systems.…”

THz CMOS On-Chip Antenna Array Using Defected Ground Structure

“…Figure 9 shows the photograph of the fabricated CMOS on-chip antenna (antenna element, 1 × 2 array, and 2 × 2 array). We measured the antenna performance by on-wafer probing in which the metal probes can affect the radiation performance of the on-chip antenna [11]. In order to reduce this effect, very long 50 Ω lines (length >300 µm (~0.7λ at 300 GHz) ) are inserted between the antenna input and RF probe pad.…”

“…To increase the gain and radiation of the frontside radiating antenna, a dielectric resonator was attached on top of the CMOS on-chip patch in [10]. The defected ground structure (DGS) was introduced by the authors to increase the radiation resistance and bandwidth of the CMOS on-chip patch antenna [11]. However, single on-chip antenna still exhibits a limited gain performance at THz frequencies.…”

“…The designed on-chip patch antenna consists of a top metal layer (M10) as a radiating patch and two lower-most metal layers (M1 and M2) as a ground plane, so that the thickness of the dielectric substrate in between can be maximized to allow for high radiation resistance. It can enable the CMOS on-chip patch antenna to have improved bandwidth and radiation efficiency [11,13]. Figure 1b shows the reference patch antenna designed at a center frequency of 300 GHz, where an inset feed is employed for the input impedance match.…”

“…Therefore, there should be research in improving the bandwidth and gain of a CMOS on-chip antenna at THz frequencies. Recently, the V-shaped patch antenna with the DGS was proposed by the authors, improving the performance of the CMOS on-chip antenna [11]. The slots in the DGS allow the leakage of the electromagnetic wave into the silicon substrate, which increases the radiation resistance and thus the bandwidth and efficiency of the antenna.…”