Micromachined Terahertz Rectangular Waveguide Bandpass Filter on Silicon-Substrate

Abstract

A micromachined 385 GHz rectangular waveguide cavity bandpass filter is presented. The proposed filter is fabricated using deep reactive ion etching on silicon substrate, with sputtered gold inner surface metallization. The vector network analyzer measured results show the lowest insertion loss is about 2.7 dB with a 15 GHz bandwidth. Effects of micro-electro-mechanical systems process on the filter's performance are discussed in detail.Index Terms-Bandpass filter (BPF), micro-electro-mechanical systems (MEMS), rectangular waveguide, terahertz (THz).

Silicon Micromachined Waveguide Quadrature-Hybrid Coupler at Terahertz Frequency Band

“…The standard WR-2.2 rectangular waveguides with the size of 559 μm×279 μm are adopted as the input and output waveguides, to make it easier to connect with external circuits. As mentioned in [18], the conductivity of an electroplated gold film is less than that of bulk gold and the surface roughness of an electroplated gold film also results in less-conductive sidewalls, consequently inducing the deterioration of the insertion loss. To ensure the design precision, these factors of micromachining process should be considered in the simulation process, in which the conductivity of electroplated gold is set as 3.96×10 7 and the roughness is set as 1 μm.…”

“…According to the observation in [18], the insertion loss of a straight waveguide fabricated by the DRIE technology is about 0.4 dB/mm in the band of 325~440 GHz, which should be taken into consideration when the operating frequency is increased to 300 GHz or higher. Therefore, the extended waveguide of the terahertz coupler should be kept as short as possible, which brings about a much smaller size coupler (about 6.3 mm×6.3 mm×1 mm) compared with the waveguide flange (about 19.05 mm×19.05 mm×4.255 mm, according to [19,20]) used in the measurement.…”

Sub-Millimeter-Wave 10 dB Directional Coupler Based on Micromachining Technique

“…According to the observation in [1], the insertion loss of a straight waveguide fabricated by the DRIE technology is about 0.4 dB/mm in the band of 325∼440 GHz, which cannot be ignored when the operating frequency is increased to 300 GHz or higher. Hence, the whole size of the directional coupler should be kept as small as possible.…”

“…Because the straight waveguide loss cannot be ignored when the frequency is up to 300 GHz [1], the length of the input/output straight waveguide should be kept as short as possible for less loss. However, it is difficult to measure all characteristics of the four-port coupler with small-size using the two-port VNA with big-size flanges.…”

Micromachined multilayer bandpass filter at 270 GHz using dual-mode circular cavities

“…Since fabrication of resonating devices at high frequencies requires high precision geometrical features for good performance and in particular for high product uniformity without postfabrication tuning, photolithographic-based micromachining, even allowing for MEMS reconfigurability [1][2], is an excellent fabrication technology for higher-order complex filters at sub-THz frequencies. Several micromachined examples of direct-coupled and cross-coupled bandpass filters designed for sub-THz frequency range have been reported [3][4][5][6][7]; all of them require a custom-made split-block assembly to connect with standard waveguide flanges. Recently, in [8], a micromachined multilayer cross-coupled filter had been implemented for Ka-band; however even for this 10-times lower frequency than in the present paper, and despite using micromachining, that design was not very robust resulting in detuning and shifting of the response with a relatively poor 8 dB return loss.…”