Innovative micromachined microwave switch with very low insertion loss

The amorphous-to-crystalline transition in Al(1.0%wtSi)/Zr and Al(Pure)/Zr multilayers grown by direct-current magnetron sputtering system has been characterized over a range of Al layer thicknesses (1.0–5.0 nm) by using a series of complementary measurements including grazing incidence X-ray reflectometry, atomic force microscopy, X–ray diffraction, and high-resolution transmission electron microscopy. The Al layer thickness transition exhibits the Si doped in Al could not only disfavor the crystallization of Al but also influence the changing trends of surface roughness and diffraction peak position of phase Al〈111〉. An interesting feature of the presence of Si in Al layer is that Si could influence the transition process in Al(1%wtSi) layer, in which the critical thickness (1.6 nm) of Al(Pure) layer in Al(Pure)/Zr shifts to 1.8 nm of Al(1.0%wtSi) layer in Al(1.0%wtSi)/Zr multilayer. We also found that the Zr-on-Al interlayer is wider than the Al-on-Zr interlayer in both systems, and the Al layers do not have specific crystal orientation in the directions vertical to the layer from selected area electron diffraction patterns below the thickness (3.0 nm) of Al layers. Above the thickness (3.0 nm) of Al layers, the Al layers are highly oriented in Al〈111〉, so that the transformation from asymmetrical to symmetrical interlayers can be observed. Based on the analysis of all measurements, we build up a model with four steps, which could explain the Al layer thickness transition process in terms of a critical thickness for the nucleation of Al(Pure) and Al(1%wtSi) crystallites.

Microwave and millimeter-wave integrated circuits and distribution networks often require two transmission lines to cross over each other. In this paper, experimental measurements and 3D-Finite Difference Time Domain (FDTD) analysis are used to characterize Coplanar Waveguide (CPW) and Finite Ground Coplanar (FGC) waveguide crossover junctions for the first time. It is shown that FGC crossover junctions have approximately 15 dB lower coupling than CPW crossover junctions with no degradation in return and insertion loss.

In this paper, we present a novel laterally actuated DC-contact three-state RF MEMS switch. Rotary electrostatic comb-drive actuators which can be rotated both clockwise and anti-clockwise are chosen as the drive mechanism of the switch and are integrated inside of the switch, hence the switch has a very compact structure. The proposed switch is designed in such a way that it can be used in antenna switch applications where having high isolation and low insertion loss are of most important operating characteristics. The switch has three operating states of ON, OFF and deep-OFF. Different FEM simulations are carried out in order to optimize RF and mechanical behavior of the switch. The switch has acceptable RF performance in a frequency range from DC up to 40 GHz with near to zero power consumption. The actuation voltage of the switch is 50 V. The switching time from OFF to ON state or deep-OFF state is 79 µs and return time to OFF state is 130 µs. The switch has an insertion loss less than ź0.87 dB up to 40 GHz, and return loss below ź21 dB at the same frequency range. The OFF state and deep-OFF state isolations are ź35 and ź60 dB up to 40 GHz, respectively.

Modern wireless communication systems demand high bandwidth and effective interference mitigation. This research introduces a compact ultra-wideband (UWB) reconfigurable antenna utilizing a Radio Frequency Micro-Electro-Mechanical Systems (RF-MEMS) switch to address these challenges. The study evaluates three antenna designs: a partially ground-fed antenna, a Co-Planar Waveguide (CPW)-fed antenna with a rectangular ground-plane slot, and a C-shaped slot UWB antenna. Reconfigurability is achieved by incorporating an RF-MEMS switch, connected to the ground-fed antenna through an open stub. The proposed antennas employ a reduced electrical size and an innovative virtual ground feed technique to provide outstanding frequency reconfigurability, along with a single-band notch function controlled by ON and OFF states of the RF-MEMS switch. The Fixed–Fixed RF-MEMS switch provides low insertion loss and high isolation, ensuring excellent RF performance. The proposed antenna design integrates an RF-MEMS switch to enable frequency reconfigurability, dynamically switching between UWB (3.1–11 GHz) and a notched band (5–6 GHz) for interference suppression. The simulated and fabricated prototype demonstrates a peak gain of 9 dBi in UWB mode, with a notch band attenuation of − 5 dBi, ensuring reliable performance across the operating range. The antenna maintains VSWR < 2 across the band except for the notched region, with stable omnidirectional radiation patterns. Compared to existing designs, the proposed structure offers compact size (28 × 23 × 1.6) mm3, superior reconfigurability, and improved gain stability, making it an excellent candidate for next-generation UWB communication systems.

In this paper we purpose a triangular split ring resonator (TSRR) loaded with co-planar waveguide (CPW) line for realizing a planar band-pass filter for miniaturization and high data rate WiMAX communication system. It consists of a 50Ω CPW line with triangular resonator etched on backside of substrate, parallel to the CPW. Because of negative permeability offered by the SRR and series capacitance this structure exhibits backward wave propagation in the vicinity of its resonant frequency. Due to the strong inductive coupling between resonator and line and periodically loading the line with narrow wires, resulting high selectivity with low insertion loss in the wide band-pass characteristic.

The application of an electrooptic sampling technique for the characterization of propagating modes of uniplanar guiding structures on GaAs is described. The characteristics of slotline and even and odd modes of coplanar waveguides (CPW) on semi-insulating GaAs substrate are investigated. The potential distribution over the cross section of each was measured. The guide wavelength for each guide was directly obtained from standing-wave measurements by electrooptic sampling, and the dispersion characteristics of CPW modes and slotline were measured from 15 to 40 GHz. >

In this paper, the design, integration, and measurement of quadrature couplers integrated in a multilayer thin-film multichip-module technology are discussed. We have investigated four- and six-finger coplanar-waveguide (CPW) Lange couplers and a coupler based on reentrant sections. Three methods for the design of CPW Lange couplers are compared for the first time. The method of Paolino consistently results in the best performance. The four-finger Lange coupler results in a -3.2+/-0.2-dB coupling bandwidth from 10.8 to 14.9 GHz, with a return loss better than -18 dB and an isolation better than -20 dB. The six-finger Lange coupler results in a -3.2+/-0.5-dB coupling bandwidth from 9.5 to 17 GHz, with a return loss and isolation better than -16 dB. The coupler using reentrant sections results in a -3.4+/-1.1-dB coupling bandwidth from 6.9 to 18.8 GHz with a return loss and isolation better than -21 dB. It is shown that CPW Lange couplers are not sensitive to planarization effects, while for the design of couplers using reentrant sections, the effect should be taken into account. The Lange couplers have the additional advantage that they are easier to design, have a lower insertion loss, and can be very well predicted using method-of-moments simulations.

New coplanar waveguide (CPW) filters with a forkshaped defected ground structure (DGS) are proposed for radio-frequency (RF) and microwave applications.The miniature CPW DGS filters developed are based on the silicon technology.The filters are able to provide the bandstop characteristics with high attenuation in the stop band and low insertion loss in the pass band.A typical filter designed for Ka-band satellite communication systems exhibits an attenuation of 26.3 dB at a resonant frequency of 28.35 GHz.

High isolation and low insertion loss is highly regarded for the devices designed for high frequency applications. A compact radio-frequency microelectromechanical systems switch on quartz substrate is presented in this paper. The high isolation is achieved by incorporating two membranes in series and shunt configuration on a single substrate while maintaining the compactness of the switch dimensions. The ohmic and capacitive switch membranes are designed in a cavity over co-planar waveguides on substrate. Spring constant, pull-in voltage, pressure distribution, squeeze film air damping, Q-factor, R, L and C for switch are calculated and analyzed by finite element modeler. Eigenfrequency analysis is also carried out using FEM to analyse the mode shape for first 6 eigenfrequencies. Biasing pads are provided on both ends of the switch for electrostatic actuation. Membranes with low spring constant are designed and optimized to work on same voltage level. Stress on membranes is analyzed and taken care of by the including meanders. This proposed switch is showing excellent isolation of $$75$$75 dB and low insertion loss of $$0.13$$0.13 dB at $$28$$28 GHz with need of actuation voltage of $$22.5$$22.5 V for both membranes in complete switch area of $$0.4$$0.4 mm$$^2$$2. The switch has wide bandwidth of $$30$$30 GHz from K and Ka band with above $$62$$62 dB of isolation.

In this paper, we have enhanced the performance of the existing switch operating at 35 GHz by using a novel optimization process and these results are compared with the existing experimental results. The same optimization process is utilized to design the switch at 5G mobile communication frequencies (38 GHz) and its performance is analyzed. The switch is designed on the coplanar waveguide having 50 Ω impedance matching and is optimized based on the wireless application system for Ka-band (27–40 GHz) at a resonance frequency of 38 GHz. The proposed switch at 38 GHz exhibits low input reflection coefficient (S11) of 13.86 dB (> 10 dB), low insertion loss (S12) of 0.44 dB (< 1 dB) and high isolation (S21) of 33 dB at Ka-band frequencies. The proposed structure is designed to have less spring constant of 2.38 N/m and actuation voltage of 11.97 V. During UP state position switch develops an ON-state capacitance of 31 fF and OFF state capacitance of 0.152 pF during downstate with a capacitance ratio of 4.90. The switch requires low switching time of 0.19 ms and it can withstand up to the force of 12.97 × 10−4 N which is generated during actuation. Thus, the proposed switch can be effectively optimized for good performance and can be used for high-frequency 5G communication applications.

Electrostatic actuation is seemingly the most prevalent method of applying forces to deformable elements in microsystems. Two factors make electrostatic actuation appealing in systems with micron-scale dimensions. First, it is associated with the physics of the system, when practical voltages (e.g. –100 V) are applied across micron-scale gaps; the resulting electrostatic fields are sufficiently high to deform elements which, in turn, are sufficiently flexible due to their micron-scale thickness. Second, electrostatic actuation is perfectly compatible with microfabrication technology used for fabricating ICs. The same fabrication processes may be used to produce isolated conducting elements that are supported by flexible suspensions.

In this letter, a planar left-handed propagating medium consisting of a coplanar waveguide (CPW) inductively coupled to split ring resonators (SRR) and periodically loaded with narrow metallic wires is proposed. The wires make the structure behave as a microwave plasma with a negative effective permittivity which covers a broad frequency range. The negative permeability required to achieve left-handed wave propagation is provided by the rings in the vicinity of their resonant frequency. The result is a structure which allows negative wave propagation in a narrow frequency band. The transmission coefficient measured in a fabricated prototype device exhibits very low insertion losses in the pass band and high-frequency selectivity. Since rings are much smaller than signal wavelength at resonance and can be easily tuned, SRR-CPW-based structures are of interest for the design of very compact microwave circuits based on left handedness.

This paper reports the design, fabrication, electrical characterization and packaging of micromachined shunt capacitive switch with low actuation voltage. These switches are fabricated on a low resistive silicon substrate using only a four mask surface micromachining process. The co-planar waveguide is patterned using chrome/gold layer. Positive photoresist S1813 is used as the sacrificial layer. The top beam membrane is made of gold. The membranes are released through a wet release process through Piranha solution. Supercritical point drying tools were used for the top beam release after wet etching to provide anti-stiction. The switches are 300 µm long with 10 μm holes on the top membrane to lower both residual stress and pull-in voltages. These switches exhibit low actuation voltages in the range of 5.5–6.4 V. The RF characterization shows that these switches have low insertion loss and high isolation in the frequency range of interest. The packaging was carried out using commercially available surface mount style RF packages. However, the whole packaging process is performed under low temperature in order to free the MEMS structures of thermally induced stress which otherwise would affect the performance of the switch. The adhesion of the die to the bottom package is excellent and is tested by die shear test. The packaged switch has passed the non-destructive pull test.

Coplanar waveguides are fabricated by directly bonding 17-μm Al foils to Si substrates with different resistivities. A lower insertion loss is observed for a Si substrate with higher resistivity since the substrate loss is decreased. Calculation using an analytical model shows that the insertion loss increases by reducing the thickness of conductors, which demonstrates the superiority of direct bonding of metal foils for realizing low-loss passive components to be integrated on semiconductor substrates.

Correlation of mechanical damage and electrical behavior of Al/Mo bilayers subjected to bending