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In this work, we propose a new concept of phase shifting by tuning the coupling distance between two parallel silicon slabs that support the propagation of an in-phase supermode. A prototype device was implemented in the 220–330-GHz band by integrating the micro-electro-mechanical system (MEMS)-actuated phase-shifting mechanism, based on two moveable parallel-coupled high-resistivity silicon slabs, inside a metallized hollow rectangular waveguide in silicon-on-insulator (SOI) micromachining technology. The prototype device has been characterized to a maximum continuous phase tunability of 550° with a maximum insertion loss of 1.87 dB achieved at 330 GHz. A maximum figure-of-merit (FOM) of 375°/dB is achieved at around 320 GHz, which presently is the highest FOM value reported for any phase shifter in the subterahertz (sub-THz) frequency range. The bandwidth covers the whole waveguide band with an average and worst case insertion loss of 1.94 and 2.5 dB, respectively, a worst case insertion-loss variation of 0.7 dB and a phase error better than 4° for all phase states. A large displacement of MEMS electrostatic comb-drive actuators that are co-fabricated in the micromachined waveguide platform is achieved by a driving voltage of 50 V. The prototype footprint is $7.3 \times 5.3$ mm2. [ABSTRACT FROM AUTHOR]

In this article, we present a new technology platform for creating compact and loss-efficient wafer-scale integrated micromachined substrate-integrated waveguides with silicon-core (Si-SIWs) for the 230–330-GHz frequency range. The silicon dielectric core enables highly integrated sub-millimeter-wave systems, since it allows for downscaling the waveguide’s cross section by a factor of 11.6, and the volume of components by a factor of 39.3, as compared to an air-filled waveguide. Moreover, geometrical control during fabrication of this type of waveguides is significantly better as compared to micromachined hollow waveguides. The measured waveguide’s insertion loss (IL) is 0.43 dB/mm at 330 GHz (0.14 dB/ $\lambda _{g}$ , normalized to the guided wavelength). A low-loss ultrawideband coplanar-waveguide (CPW) transition is implemented to enable direct measurements of devices and circuits in this waveguide platform, and this is also the very first CPW-to-SIW transition in this frequency range. The measured IL of the transition is better than 0.5 dB (average 0.43 dB above 250 GHz), which is lower than for previously reported CPW-to-SIW transitions even at 3 times lower frequencies; the return loss is better than 14 dB for 75% of the band. As devices examples implemented in this platform, a filter and H-plane waveguide bends are shown. The waveguides and the devices are manufactured by deep-silicon etching using a cost-efficient two-mask micromachining process. [ABSTRACT FROM AUTHOR]

This paper investigates the fabrication accuracy and repeatability of micromachined quadruplet filters designed at a center frequency of 270 GHz with a 5-GHz bandwidth using a versatile multilayer chip platform which allows for axially arranged waveguide ports. A large number of narrowband silicon-micromachined filters arranged on multiple chips are investigated for fabrication imperfections, assembly misalignment, and fabrication yield, employing fabrication-prediction and different chip-to-chip self-alignment feature strategies. A numerical technique for characterization of the entire fabrication process of the filters through extracting the error statistics for coupling coefficients of a large number of different samples from separately assembled chips is proposed. A total of 47 test filters in effectively 15 different design variants have been fabricated in two fabrication runs, evaluated, and analyzed. The most critical sources of errors are determined. The expected accuracy of the entire filters fabrication process is demonstrated through the yield analysis based on the collected error statistics. [ABSTRACT FROM AUTHOR]

This paper presents novel ultracompact waveguide bandpass filters that exhibit pseudoelliptic responses with the ability to place transmission zeros on both sides of the passband to form sharp rolloffs. The filters contain E -plane extracted pole sections (EPSs) cascaded with cross-coupled filtering blocks. Compactness is achieved by the use of evanescent mode sections and closer arranged resonators modified to shrink in size. The filters containing nonresonating nodes are designed by means of the generalized coupling coefficients’ extraction procedure for the cross-coupled filtering blocks and EPSs. We illustrate the performance of the proposed structures through the design examples of third- and fourth-order filters with center frequencies of 9.2 and 10 GHz, respectively. The sizes of the proposed structures suitable for fabricating using the low-cost {E} -plane waveguide technology are 38% smaller than ones of the {E}$ -plane extracted pole filter of the same order. [ABSTRACT FROM AUTHOR]