Redundancy RF MEMS Multiport Switches and Switch Matrices

The objective of this paper is to investigate novel configurations of planar multiport radio-frequency (RF) microelectromechanical systems (MEMS) C-type and R-type switches and redundancy switch matrices for satellite communications. An in-house monolithic fabrication process dedicated to electrostatic multiport RF MEMS switches and switch matrices is developed and fine tuned. The proposed C-type switch is a four-port device with two operational states. This switch exhibits an insertion loss of less than 0.3 dB and isolation of about 25 dB at satellite C-band frequency range. The novel R-type switch is also a four-port device with an additional operational state. The measured results show an insertion loss of better than 0.4 dB and an isolation of better than 25 dB at C-band. This is the first time that an R-type RF MEMS switch is ever reported. Several of these switches are integrated in the form of redundancy switch matrices, and two novel monolithic five to seven redundancy switch matrices are developed, fabricated, and tested. It is shown that the additional operating state of the R-type switch not only decreases the number of elements by 50% but also reduces the size drastically     

A comparative study of two techniques for improving power‐handling capability of CMOS T/R switches

This article proposes an asymmetric topology for transmit/receive (T/R) switches and more importantly presents a comparative study of both LC‐tuned and resistive body‐floating techniques for improving the power‐handling capability of the T/R switches in the same 0.18‐μm triple‐well CMOS. It is shown from simulations and measurements that the switches adopting either technique achieve comparable performances. For instance, the switch employing the LC‐tuned body‐floating technique exhibits insertion loss of 1.5 dB, isolation of 23.5 dB, and power‐handling capability of 22.5 dBm at 5.2 GHz, whereas the switch using the resistive body‐floating technique exhibits insertion loss of 1.3 dB, isolation of 24 dB, and power‐handling capability of 22.2 dBm, respectively. Therefore, one can conclude that the asymmetric topology with the resistive body‐floating technique is more suitable for designing T/R switches for wireless local area network applications as it consumes smaller silicon area. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010.     

Novel Reliable RF Capacitive MEMS Switches With Photodefinable Metal–Oxide Dielectrics

In this paper, the design, fabrication, and measurement of reliable low-cost capacitive radio-frequency microelectromechanical systems switches with a novel fabrication approach using direct photodefinable high-k metal oxides are presented. In this approach, a radiation-sensitive metal-organic precursor is deposited via spin coating and converted to a high-k metal oxide via ultraviolet exposure. Measurements of the bridge-type switches have been done up to 40 GHz. These switches are reliable (> 340 million cycles) and exhibited low insertion loss (about 0.3 dB at 20 GHz) and better isolation (about 24 dB at 20 GHz) at frequencies below the resonant frequency as compared to switches that are fabricated using a simple silicon nitride dielectric.     

A Liquid–Solid Direct Contact Low-Loss RF Micro Switch

This paper reports the design, fabrication, and testing of a liquid-metal (LM) droplet-based radio-frequency microelectromechanical systems (RF MEMS) shunt switch with dc-40 GHz performance. The switch demonstrates better than 0.3 dB insertion loss and 20 dB isolation up to 40 GHz, achieving significant improvements over previous LM-based RF MEMS switches. The improvement is attributed to use of electrowetting on dielectric (EWOD) as a new actuation mechanism, which allows design optimized for RF switching. A two-droplet design is devised to solve the biasing problem of the actuation electrode that would otherwise limit the performance of a single-droplet design. The switch design uses a microframe structure to accurately position the liquid-solid contact line while also absorbing variations in deposited LM volumes. By sliding the liquid-solid contact line electrostatically through EWOD, the switch demonstrates bounceless switching, low switch-on time (60 mus), and low power consumption (10 nJ per cycle).     

RF-MEMS Capacitive Switches Fabricated Using Printed Circuit Processing Techniques

This paper presents radio frequency microelectromechanical systems (RF-MEMS) capacitive switches fabricated using printed circuit processing techniques. The key feature of this approach is the use of most commonly used flexible circuit film, Kapton E polyimide film, as the movable switch membrane. The physical dimensions of these switches are in the mesoscale range. For example, electrode area of a typical capacitive shunt switch on coplanar waveguide (CPW) is 2 mmtimes1 mm, respectively. A CPW shunt switch with insertion loss <0.4 dB and isolation >10 dB in the frequency range of 8 to 30 GHz is reported. K-band, Ku-band, and X-band high-isolation CPW shunt switches designed by inductive compensation of the switch down-position capacitance are also presented. Inductance compensation has been implemented by introducing inductive step-in-width junctions in the MEMS switch electrode. The K-band switch provides a maximum isolation value of 54 dB at 18 GHz. For the K-band switch, the insertion loss is less than 0.3-0.4 dB in the frequency range of 1-30 GHz and the isolation values are better than 20 dB in the frequency range of 12 to 30 GHz. The Ku-band switch provides a maximum isolation of 46 dB at 16.5 GHz. For the Ku-band switch, the insertion loss is less than 0.4-0.45 dB in the frequency range of 1-30 GHz and the isolation is greater than 20 dB in the frequency range of 12 to 22 GHz. The X-band switch provides a maximum isolation value of 32 dB at 10.6 GHz. The insertion loss is less than 0.25-0.3 dB in the frequency range of 1-18 GHz and the isolation is better than 20 dB in the frequency range of 8.5 to 13.5 GHz for the X-band switch. The measured typical pull-down voltage is in the range of 100-120 for this type of switches. These switches are uniquely suitable for monolithic integration with printed circuits and antennas on organic laminate substrates     

A 60‐GHz single‐pole‐single‐throw switch in 65‐nm bulk CMOS

A single‐pole‐single‐throw (SPST) switch in a π‐network topology is designed in a 1.2‐V 65‐nm bulk CMOS RF process for millimeter‐wave applications in the 60‐GHz band from 57 to 66 GHz. The SPST switch with an active chip area of only 96 μm × 140 μm achieves the measured 11‐dB return loss, 1.6‐dB insertion loss, and 27.9‐dB isolation at 60 GHz. The SPST switch also shows the simulated power‐handling capability of 11.4 dBm and switching speed of 1 ns at 60 GHz. These results clearly demonstrate that the SPST switch in CMOS rivals the performance of SPST switches in GaAs and therefore has potential to be used in highly‐integrated 60‐GHz CMOS radios. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.     

A Highly Reliable Lateral MEMS Switch Utilizing Undoped Polysilicon as Isolation Material

The lateral actuated switch requires an isolation structure to provide mechanical coupling and electrical isolation between the actuator and the contacts. This isolation structure usually imposes extra difficulty on the fabrication process. In previous reports, we demonstrated a thermal actuated lateral switch, where the nitride isolation structure was a weak point, leading to reliability problems. In this paper, we developed a modified switch utilizing undoped polysilicon as the isolation material. The undoped-polysilicon isolation structure requires only one extra step of sheltered implantation, and it provides robust mechanical connection. A 20-mum-long undoped-polysilicon isolation structure has a current leakage of less than 2 nA under a 15-V operation voltage. The proposed switch works under a 12-V driving voltage with 60-mW input power. The time response is measured to be 130 mus, and a maximum operation frequency of 4.5 kHz is reached. An ON-state insertion loss of -0.41 dB at 20 GHz and an OFF-state isolation of -20 dB at 20 GHz have been achieved on the normal low-resistivity silicon substrate. The undoped-polysilicon isolation method can be used in other surface-micromachined lateral switches as well.     

MEMS capacitive series switch fabricated using PCB technology

In this article, an RF MEMS capacitive series switch fabricated using printed circuit processing techniques is discussed. Design, modeling, fabrication, and characterization of the CPW series switch are presented. An example CPW series capacitive switch with insertion loss less than 0.5 dB in the frequency range of 13–18 GHz and isolation better than 10 dB up to 18 GHz is discussed. The switch provides a minimum insertion loss of about 0.1 dB at the self‐resonance frequency of 16 GHz and a maximum isolation of about 42 dB at 1 GHz. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007.     

A lateral RF MEMS capacitive switch utilizing parylene as dielectric

A novel lateral RF MEMS capacitive switch was reported in this paper. This switch employed parylene as the dielectric material, taking advantages of its low temperature deposition and conformal coating. The low resistivity single crystalline silicon served as the material of the mechanical structures. The switch was fabricated by bulk micromachining processes with only two lithographic masks and a shadow mask. The dynamical response, parylene insulation performance, and RF performances of the fabricated switch were characterized, respectively. The switching time from the open state to the close state was 105 μs at a loaded voltage of 78 V, while 15.6 μs from the close state to the open state. The isolation was better than 15 dB from 20 to 40 GHz, and the maximal isolation was 23.5 dB at 25 GHz; while the insertion loss was below 1.4 dB at 25 GHz, when bonding wires connected the ground lines. These results verify that the parylene is a good candidate material to act as sidewall dielectric to realize the lateral capacitive switch.     

RF MEMS membrane switches on GaAs substrates for X-band applications

Micromechanical switches have demonstrated great potential at microwave frequencies. For low-loss applications at microwave frequencies, it is important to use high-resistivity substrates. This paper presents the design and fabrication of the shunt-capacitive MEMS switch on GaAs substrates. Analytical mechanical and impedance models of the membrane switch are given, and the results are confirmed by using the ANSYS and HFSS software, respectively. A surface micromachining process, which is compatible with the conventional millimeter-wave integrated circuits (MMICs) fabrication technology, was adopted to fabricate the RF switch on GaAs substrates. Its S-parameter was taken using a HP8510C vector network analyzer and a Cascade Probe station. The measured insertion loss of the switch and its associated transmission line is less than 0.25 dB from 1 to 25.6 GHz, and the isolation may reach -42 dB at its self-resonate frequency of 24.5 GHz. The actuation voltage is about 17 V. The switch has demonstrated lifetimes as long as 5/spl times/10/sup 6/ cycles. The wideband high performance in isolation and insertion loss offers the monolithic integration capability with GaAs MMICs.     

Design and modeling of a novel RF MEMS series switch with low actuation voltage

This paper presents the design, analysis, modeling and simulation of a novel RF MEMS series switches with low actuation voltage. A mechanical modeling is presented to describe the behavior of the series switch. The switch is designed with special mechanical structures. The novel mechanical and mathematical modeling of the switch leads to calculation of the accurate actuation voltage. The spring constant has been calculated in relation to the presence of the residual stress in the beam. The calculated spring constant for this beam is used to determine the accurate actuation voltage. The size of the switch is 60 × 110 µm². The designed RF MEMS series switch was simulated using Intellisuite MEMS tool. He calculated actuation voltage is 4.05 V and simulated one is 4.2 V for 0.6 µm beam thickness. The calculated result is also very close with simulated one. The proposed switch compared with other electrostatic switches has low actuation voltage and small size. The RF characteristics were simulated using HFSS software and the switch has good RF performance. The insertion loss of 0.067 dB, return loss of 26 dB and isolation of 16 dB were achieved at 40 GHz.     

A novel DMTL capacitive switch with electrostatic actuation MAM capacitors

A novel DMTL capacitive switch with electrostatic actuation metal–air–metal (MAM) capacitors is presented. The top board of MAM capacitors will be pulled down together with the switch bridge. It has higher isolation in down-state than DMTL capacitive switch and has lower insert loss and higher self-actuation RF power comparing with MEMS shunt capacitive switch. Two of the novel DMTL capacitive switches are designed for high isolation and high self-actuation RF power, respectively. The calculated result shows that both of the two novel switches have lower insert loss than the MEMS shunt capacitive switch. The self-actuation RF power of them are 4 and 2.4 times that of MEMS shunt capacitive switch, respectively, at the cost of ?6.23 and ?3.54?dB reduction in isolation (30?GHz).     

High isolation microstrip GaN‐HEMT Single‐FET Switch

In this contribution an analytical approach to the design of high‐isolation microwave transmission line‐resonated switches is presented. Simulated and measured performance of a GaN HEMT single‐FET switch cell topology and the one of a complete SPDT using the proposed approach are presented to demonstrate the approach feasibility and effectiveness. The resulting SPDT, operating at X Band, is featured by 1 dB insertion loss, isolation better than 37 dB all over the operating bandwidth and a power handling capability higher than 39 dBm. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010.     

Design of novel compact anti-stiction and low insertion loss RF MEMS switch

A novel torsional RF MEMS capacitive switch design on silicon substrate is presented. The optimized switch topology such as reduction in up-state capacitance results in insertion loss better than ?0.1 dB till 20 GHz. Off to on state capacitance ratio is also improved by 18 fold and isolation is better than ?43 dB at 9.5 GHz. The achieved on state return loss is ?38 dB as compared to ?21 dB at 9.5 GHz. An optimized reduction in contact area and use of floating metal layer increases the switching speed from 56 to 46 μsec. It also increases the switch reliability by alleviating the stiction.     

The SiOG-based single-crystalline silicon (SCS) RF MEMS switch with uniform characteristics

This paper details single-crystalline silicon (SCS) direct contact radio frequency microelectromechanical systems (RF MEMS) switch designed and fabricated using an SiOG (silicon-on-glass) substrate, so as to obtain higher fabrication and performance uniformity compared with a conventional metal switch. The mechanical and electrical performances of the fabricated silicon switch have been tested. In comparison with a conventional metallic MEMS switch, we can obtain higher productivity and uniformity by using SCS, because it has very low stresses and superior thermal characteristics as a structural material of the switch. Also, by using the SiOG substrate instead of an SOI substrate, fabrication cost can be significantly reduced. The proposed switch is fabricated on a coplanar waveguide (CPW) and actuated by electrostatic force. The designed chip size is 1.05 mm/spl times/0.72 mm. Measured pull-in voltage and actuation voltage were 19 V and 26 V, respectively. Eighteen identical switches taken randomly throughout the wafer showed average and standard deviation of the measured pull-in voltage of 19.1 and 1.5 V, respectively. The RF characteristics of the fabricated switch from dc to 30 GHz have been measured. The isolation and insertion loss measured on the four identical samples were -38 to -39 dB and -0.18 to -0.2 dB at 2 GHz, respectively. Forming damping holes on the upper electrode leads to a relatively fast switching speed. Measured ON and OFF time were 25 and 13 /spl mu/s, respectively. In the switch OFF state, self-actuation does not happen up to the input power of 34 dBm. The measured holding power of the fabricated switch was 31 dBm. Stiction problem was not observed after 10/sup 8/ cycles of repeated actuation, but the contact resistance varied about 0.5-1 /spl Omega/ from the initial value.     

Design and analysis of a RF MEMS shunt switch using U-shaped meanders for low actuation voltage

This paper presents the design and simulation of RF MEMS switch using uniform U-Shaped meanders. High isolation and low insertion loss are the main performance parameters enhanced by considering the inductive sections on the design and developing high capacitance using HfO₂ as a dielectric medium. The inductive sections in the design help maintain the device at resonance. The proposed uniform U-shaped meanders lower the spring constant and reduce the Pull-in-voltage of the switch. The performance characteristics are observed by simulating the proposed switch in the electromechanics environment using the COMSOL FEM tool. The switch exhibits a low Pull-in-voltage of 5.2 V with a very low switching time of 23.1 µs. Total capacitance of 42.19 fF is formed during upstate which provides a low insertion loss of less than 0.1 dB. Capacitance of 19.11 pF during downstate provides high isolation of − 42.11 dB.

     

Design and modeling of a continuously variable piezoelectric RF MEMS switch

A structure for a piezoelectrically actuated capacitive RF MEMS switch that is continuously variable between the ON state and the OFF state has been proposed. The device is based on variable capacitance using a cantilever fixed at both ends that is actuated using a lead zirconate titanate thin film. Because the device is contactless, the reliability issues common in contact-type RF MEMS switches can be avoided. A comprehensive mathematical model has been developed in order to study the performance of the device, and allow for design optimization. Electrical measurements on test structures have been compared with the performance predicted by the model, and the results used to design a prototype RF MEMS switch. The model and simulations indicate the proposed switch structure can provide an insertion loss better than 0.7 dB and an isolation of more than 10 dB between 6 and 14 GHz with an actuation voltage of 22.4 V. The state of the device is continuously variable between the ON state and the OFF state, with a tunable range of capacitance of more than 15\(\times \).     

Design and simulation of a thermally actuated MEMS switch for microwave circuits

The design, modeling, and optimization of a novel, thermally actuated CMOS‐MEMS switch are presented in this article. This series capacitive MEMS switch solves the substrate loss and down‐state capacitance degradation problems commonly plaguing MEMS switches. The switch uses finger structure for capacitive coupling. The vertical bending characteristic of bimorph cantilever beams under different temperatures is utilized to turn the switch on and off. A set of electrical, mechanical, and thermal models is established, and cross‐domain electro‐thermo‐mechanical simulations are performed to optimize the design parameters of the switch. The fabrication of the switch is completely CMOS‐process compatible. The design is fabricated using the AMI 0.6 μm CMOS process and a maskless reactive‐ion etching process. The measured results show the insertion loss and isolation are 1.67 and 33 dB, respectively, at 5.4 GHz, and 0.36 and 23 dB at 10 GHz. The actuation voltage is 25 V and the power consumption is 480 mW. This switch has a vast number of applications in the RF/microwave field, such as configurable voltage control oscillators, filters, and configurable matching networks. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

串联电容式RF MEMS开关设计与制造研究

介绍了一种串联电容式RF MEMS开关的设计与制造。所设计的串联电容式RF MEMS开关利用薄膜淀积中产生的内应力使MEMS桥膜向上发生翘曲,从而提高所设计的开关的隔离度,克服了串联电容式RF MEMS开关通常只有在1GHz以下才能获得较高隔离度的缺点。其工艺与并联电容式RF MEMS开关完全相同,解决了并联电容式RF MEMS开关不能应用于低频段(<10GHz)的问题。其插入损耗为-0.88dB@3GHz,在6GHz以上,插入损耗为-0.5dB;隔离度为-33.5dB@900MHz、-24dB@3GH和-20dB@5GHz,适合于3~5GHz频段的应用。     

Analysis of a novel RF MEMS switch using different meander techniques

In this paper, two types of RF MEMS switches namely step structure and Normal beam structure are designed and analyzed using different meander techniques. Three techniques namely plus, zigzag and three-square meander were used to lower the pull-in voltage. The actuating beam is designed with the rectangular perforations affects the performance of a switch by lowering the pull-in voltage, switching speed and results in better isolation. In this paper a comparative analysis is done for all three meander techniques with and without perforations on the beam. Total six structures have been designed with the combination three meanders and two different beam structures. The proposed stepdown structure exhibits high performance characteristics with a very low pull-in voltage of 1.2 V having an airgap of 0.8 µm between the actuation electrodes. The gold is used as beam material and HfO₂ as the dielectric material such that the upstate and downstate capacitance is seen as 1.02 fF and 49 fF. The FEM analysis is done to calculate the spring constant and thereby the pull-in voltage and behavior of the switch is studied with various parameters. The switch with a step structure and three-square meander configuration has shown best performance of all by requiring a pull-in voltage of 1.2 V and lower switching time of 0.2 µs. The proposed switch also exhibits good RF performance characteristics with an insertion loss below − 0.07 dB and return loss below − 60 dB over the frequency range of 1–40 GHz. At 28 GHz a high isolation of − 68 dB is exhibited.