In this paper, we report a new push-pull-type SPDT (single pole double throw) switch actuated by the combination of electromagnetic and electrostatic forces for low power and low voltage operation. The switch is initially actuated by large electromagnetic force to change its state and is held to maintain its state by applying electrostatic force to reduce static power consumption. The electromagnetic force can be easily generated at low voltage. The maximum actuation voltage is below 4.3 V and the required energy is 15.4 μJ per switching. It achieves signal isolation of −54 dB and insertion loss of −0.16 dB at 2 GHz, respectively. For 20 GHz operation, isolation and insertion loss were measured as −36 dB and −0.52 dB, respectively. The proposed SPDT switch combines two switching elements in a single structure, simplifying the overall structure and control signals and eliminating mismatches between the two switching elements. The dimension of the switch has been optimized using FEM simulation and analytical calculations. We have successfully carried out a lifetime test over more than 166 million cycles with the maximum actuation voltage below 4.3 V. (Some figures in this article are in colour only in the electronic version)

/pdf/design-and-fabrication-of-a-single-membrane-push-pull-spdt-1vgi5vzopw.pdf

Design and fabrication of a single membrane push-pull SPDT RF MEMS switch operated by electromagnetic actuation and electrostatic hold

This paper reports on a mechanically tri-stable switch mechanism based on laterally moving electrostatic curved-electrode actuators. The switch is configured in a 'true' single-pole-double-throw configuration (SPDT), i.e. a single-switch mechanism allows for the input signal to be switched between two output ports. The switch has three stable states: (1) input to first output; (2) switch off; (3) input to second output. Because of a latching mechanism, these states are mechanically stable, i.e. they are maintained without applying external actuation energy. The fabrication of the switches is done by a single photolithographical step and deep etching of a silicon-on-glass wafer which is subsequently coated with sputtered gold. The switch design features active opening, and the contact force is created passively by the deflected cantilevers. The curved-electrode actuators are utilized close to their end position where they develop their maximum force to guarantee a very large opening force which makes the switch less susceptible for contact stiction. The actuation voltages for different designs and functions of the switches are between 30 and 85 V.

https://nocweba.ntu.edu.sg/laq_mems/journal%20papers/2006/Mechanically%20tri-stable,%20true%20single-pole-double-throw%20(SPDT)%20switches.pdf

Mechanically tri-stable, true single-pole-double-throw (SPDT) switches

This paper reports on novel electrostatically actuated dc-to-RF metal-contact microelectromechanical systems (MEMS) switches, featuring a minimum transmission line discontinuity since the whole switch mechanism is completely embedded inside the signal line of a low-loss 3-D micromachined coplanar waveguide. Furthermore, the switches are based on a multistable interlocking mechanism resulting in static zero-power consumption, i.e., both the onstate and the offstate are maintained without applying external actuation energy. Additionally, the switches provide with active opening capability, potentially improving the switch reliability, and enabling the usage of soft low-resistivity contact materials. Both two-port single-pole-single-throw (SPST) switches featuring mechanical bistability and three-port single-pole-double-throw (SPDT) T-junction switches with four mechanically stable states are presented. The switches, together with the transmission lines, are fabricated in a single photolithography process. The loss created by the discontinuity of the switch mechanism alone is 0.08 dB at 20 GHz. Including a 500 m long transmission line with less than 0.4 dB/mm loss up to 20 GHz, the total insertion loss of the two-port devices is 0.15 and 0.3 dB at 2 and 20 GHz, and the isolation is 45 and 25 dB at 2 and 20 GHz. The three-port switches, including their T-junction transmission line, have an insertion loss of 0.31 and 0.68 dB, and an isolation of 43 and 22 dB, at 1 and 10 GHz, respectively. Actuation voltages are 23-39 V for the two-port switches and 39-89 V for the three-port switches. The microwave propagation in the micromachined transmission line and the influence of the different switch designs were analyzed by finite-element method (FEM) simulations of electromagnetic energy and volume current distributions, proving the design advantages of the proposed concept.

/pdf/static-zero-power-consumption-coplanar-waveguide-embedded-dc-6pg394rzhm.pdf

Static Zero-Power-Consumption Coplanar Waveguide Embedded DC-to-RF Metal-Contact MEMS Switches in Two-Port and Three-Port Configuration

In this paper, the fabrication of a wireless mobile unit containing an electrochemical detection module and a 3-channel high-voltage power supply (HVPS) designed for microchip CE is described. The presented device consists of wireless global positioning system controlled robotics, an electrochemical detector utilizing signal conditioning analog circuitry and a digital feedback range controller, a HVPS, an air pump, and a CE microchip. A graphical user interface (LabVIEW) was also designed to communicate wirelessly with the device, from a distant personal computer communication port. The entire device is integrated and controlled by digital hardware implemented on a field programmable gate array development board. This lab-on-a-robot is able to navigate to a global position location, acquire an air sample, perform the analysis (injection, separation, and detection), and send the data (electropherogram) to a remote station without exposing the analyst to the testing environment.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/elps.200800215

Lab-on-a-robot: integrated microchip CE, power supply, electrochemical detector, wireless unit, and mobile platform.

Due to their high isolation, low insertion loss, high linearity, and low power consumption, microelectromechanical systems (MEMS) switches have drawn much attention from researchers in recent years. In this paper, we introduce the research status of MEMS switches in different bands and several reliability issues, such as dielectric charging, contact failure, and temperature instability. In this paper, some of the following methods to improve the performance of MEMS switches in high frequency are summarized: (1) utilizing combinations of several switches in series; (2) covering a float metal layer on the dielectric layer; (3) using dielectric layer materials with high dielectric constants and conductor materials with low resistance; (4) developing MEMS switches using T-match and π-match; (5) designing MEMS switches based on bipolar complementary metal–oxide–semiconductor (BiCMOS) technology and reconfigurable MEMS’ surfaces; (6) employing thermal compensation structures, circularly symmetric structures, thermal buckle-beam actuators, molybdenum membrane, and thin-film packaging; (7) selecting Ultra-NanoCrystalline diamond or aluminum nitride dielectric materials and applying a bipolar driving voltage, stoppers, and a double-dielectric-layer structure; and (8) adopting gold alloying with carbon nanotubes (CNTs), hermetic and reliable packaging, and mN-level contact.

https://www.mdpi.com/2072-666X/9/4/185/pdf

Research and Analysis of MEMS Switches in Different Frequency Bands

This paper presents the design and optimization of the X-band microelectromechanical system (MEMS) capacitive switch using an electrical model and a mechanical model. The electrical model can accurately extract the resistance, capacitance and inductance of the switch. Based on the electrical model, a single-bridge switch and double-bridge switch with serpentine folded suspensions are proposed to achieve higher isolation compared to a typical MEMS capacitive switch at X-band frequencies. The measurement results show an isolation of 16.5–28 dB for single-bridge switch and 25–35 dB for double-bridge switch, both at 10–13 GHz. The mechanical performance is measured using an optoelectronic laser interferometric system. Due to the low effective spring constant of the serpentine folded suspensions, only 20.4 V of pull-down voltage is required. An improved fabrication process using surface and bulk micromachining techniques is also described.

https://nocweba.ntu.edu.sg/laq_mems/journal%20papers/2005/High%20isolation%20X-band%20MEMS%20capacitive%20switches.pdf

High isolation X-band MEMS capacitive switches

A dc 6 GHz single-pole double-throw (SPDT) switching circuit that employs lateral metal-contact micromachined switches is investigated. The lateral metal-contact switch consists of a set of quasi-finite ground coplanar waveguide (FGCPW) transmission lines and a high-aspect-ratio cantilever beam. A single-pole single-throw (SPST) lateral micromachined switch has an insertion loss of 0.08 dB and a return loss of 32 dB at 5 GHz. The isolation is 32 dB at 5 GHz. The measured insertion loss of the SPDT switching circuit is below 0.75 dB, whereas the return loss is higher than 19 dB at 5 GHz. The isolation at 5 GHz is 33 dB. Pull-in voltage of the switch is 23.3 V and switching time is 35 μs. The size of the SPDT switching circuit is 1.2 mm × 1.5 mm. A main advantage of this circuit structure is simple fabrication process with high yield (>90%) based on the deep reactive ion etching (DRIE) technique of silicon-on-insulator (SOI) wafer and shadow mask technology.

https://nocweba.ntu.edu.sg/laq_mems/journal%20papers/2005/A%20single-pole%20double-throw%20circuit%20using%20lateral%20metal-contact%20micromachined%20switches.pdf

M. Tang

Papers

High isolation X-band MEMS capacitive switches

A single-pole double-throw (SPDT) circuit using lateral metal-contact micromachined switches