Low-Loss Low-Cost Substrate-Integrated Waveguide and Filter in GaAs IPD Technology for Terahertz Applications

Abstract

A low-loss and low-cost terahertz (THz) substrate-integrated waveguide (SIW) and a SIW filter implemented in a commercially-available GaAs integrated-passive-devices (IPD) technology are proposed for THz applications. Ellipse vias penetrating through a 100-μm thick GaAs substrate are employed to realize a low-loss SIW. The via's orientation is designed as being transverse, instead of being longitudinal, to the propagation direction of the input wave, which can improve the insertion loss by 2.7 dB at 415 GHz due to lower signal leakage from the waveguide. The proposed SIW is able to provide simulated insertion loss of only 0.39 dB/mm, i.e., 0.14 dB/λg, at 340 GHz. A new SIW filter structure using the ellipse vias is proposed which not only successfully realizes a low-loss fourth-order Chebyshev filter under hard design-rule-check (DRC) rules imposed by the IPD technology, but also can enhance out-of-band rejection by 10.5 dB at 390 GHz as compared with conventional waveguide filters. A slot-coupled coplanar waveguide (CPW) to SIW transition structure without any impedance tuning stub required is also proposed to measure the proposed SIW and SIW filter. The proposed transition structure can give simulated insertion loss of 0.7 dB at 340 GHz while keeping return loss better than 10 dB from 307 to 374 GHz. Eight samples are measured to demonstrate the robustness of the proposed designs against process variations. Experimental results show that the proposed transition structure with a 220-μm long SIW and the SIW filter can provide measured insertion loss of 0.7 and 3.6 dB at 327.5 GHz, respectively. The reasons for the discrepancy between the simulation and measurement results are identified and discussed in detail. As compared with prior works, the proposed SIW and SIW filter exhibit lower loss, lower cost, higher repeatability, higher reliability, and mass-producible capability. To the best of the authors' knowledge, this is the first demonstration of the THz SIW and THz SIW filter designs using a commercially-available and mass-producible IPD technology reported thus far.

THz electronics for sensing and communication applications

“…On-chip microstrip lines and coplanar waveguides at THz frequencies suffer from high insertion loss due to high dielectric and ohmic losses. As illustrated in Figure 2, a low-loss substrate-integrated waveguide (SIW) implemented in a GaAs IPD carrier was proposed to address the lossy transmission lines 11 . Ellipse vias with an optimized orientation provided by the technology are used to construct the sidewall of the waveguide.…”

High-Q terahertz bandstop filter via cuboid frame structure

“…The terahertz (THZ) wave is between the electromagnetic wave and visible light [1][2][3], and exhibits many specific electromagnetic properties; thereby it has been widely used in nondestructive testing, imaging technology and medical diagnosis [4][5][6][7]. A THZ filter, such as a bandpass filter or a bandstop filter, is one of the core parts for detecting applications, which has prompted intensive research in recent decades [8][9][10]. Among them, the bandstop filter can filter a little interference signal and pass most of a target signal in a THZ band, * Authors to whom any correspondence should be addressed.…”

On‐chip miniaturized bandpass filter using gallium arsenide‐based integrated passive device technology

“…An IPD‐based wideband BPF is presented in Reference 10, while its upper band rejection needs to be enhanced. A SIW‐based filter is fabricated by using GaAs IPD technology for Terahertz frequency band, which has a compact size 11 . An ultra‐wide upper stopband GaAs IPD filter shows in Reference 12, but its rectangular coefficient still needs to be improved.…”