Tunable lowpass and bandpass lumped-element filters employing barium-strontium-titanate (BST)-based capacitors are presented A new metallization technique is used, which improves the quality factor of the tunable BST capacitors by a factor of two The lowpass filter has an insertion loss of 2 dB and a tunability of 40% (120-170 MHz) with the application of 0-9 V DC bias The bandpass filter (BPF) has an insertion loss of 3 dB and a tunability of 57% (176-276 MHz) with the application of 0-6 V DC The third-order intercept point of the BPF was measured to be 19 dBm with the application of two tones around 170 MHz

Voltage-controlled RF filters employing thin-film barium-strontium-titanate tunable capacitors

This paper presents a ruthenium metal-contact RF microelectromechanical system switch based on a corrugated silicon oxide/silicon nitride diaphragm. The corrugations are designed to substantially reduce the influence of the fabrication-induced stress in the membrane, resulting in a highly insensitive design to process parameter variations. Furthermore, a novel multilayer metal-contact concept, comprising a 50-nm chromium/50-nm ruthenium/500-nm gold/50-nm ruthenium structure, is introduced to improve the contact reliability by having a hard-metal surface of ruthenium without substantial compromise in the contact and transmission-line resistances, which is shown by theoretical analysis of the contact physics and confirmed by measurement results. The contact resistance of the novel metallization stack is investigated for different contact pressures and is compared to pure-gold contacts. The contact reliability is investigated for different dc signal currents. At a measurement current of 1.6 mA, the Ru-Au-Ru contacts have an average lifetime of about 100 million cycles, whereas the Au-Au contacts reach 24 million cycles only. For larger signal currents, the metal contacts have proven to be more robust over the Au-Au contacts by a factor of ten. The measured pull-in voltage is reduced significantly from 61 V for flat diaphragm to 36 V for corrugated diaphragm with the introduction of corrugation. The measured RF isolation with a nominal contact separation of 5 mum is better than -30 dB up to 4 GHz and still -21 dB at 15 GHz, whereas the insertion loss of the fully packaged switch including its transmission line is about -0.7 dB up to 4 GHz and -2.8 dB at 15 GHz.

A Ruthenium-Based Multimetal-Contact RF MEMS Switch With a Corrugated Diaphragm

In this paper, we present a new type of rf MEMS switch with low actuation voltage and high isolation, for high rf power and reliability applications in telecommunication. ‘Symmetric toggle switch’ (STS) is based on push–pull mechanism and utilizes torsion springs and levers, placed symmetrically and transverse to CPW line. The switches designed for 8–14 GHz applications have analytically calculated and FEM simulated actuation voltages in the range of 8–10 V. The simulated insertion loss and isolation for the devices are 0.25 and 35 dB, respectively, at 10 GHz. The fabrication process and preliminary experimental results are also presented.

Symmetric toggle switch—a new type of rf MEMS switch for telecommunication applications: Design and fabrication

Radio frequency (RF) microelectromechanical systems (MEMS) have been pursued for more than a decade as a solution of high-performance on-chip fixed, tunable and reconfigurable circuits. This paper reviews our research work on RF MEMS switches and switching circuits in the past five years. The research work first concentrates on the development of lateral DC-contact switches and capacitive shunt switches. Low insertion loss, high isolation and wide frequency band have been achieved for the two types of switches; then the switches have been integrated with transmission lines to achieve different switching circuits, such as single-pole-multi-throw (SPMT) switching circuits, tunable band-pass filter, tunable band-stop filter and reconfigurable filter circuits. Substrate transfer process and surface planarization process are used to fabricate the above mentioned devices and circuits. The advantages of these two fabrication processes provide great flexibility in developing different types of RF MEMS switches and circuits. The ultimate target is to produce more powerful and sophisticated wireless appliances operating in handsets, base stations, and satellites with low power consumption and cost.

/pdf/rf-mems-switches-and-integrated-switching-circuits-2vsihyk7su.pdf

RF MEMS Switches and Integrated Switching Circuits

Two novel lateral metal-contact radio-frequency microelectromechanical system (RF MEMS) switches are reported. These switches are implemented with quasi-finite ground coplanar waveguide (FGCPW) configuration and actuated by applying electrostatic force on a high-aspect-ratio cantilever beam. It is demonstrated that the insertion loss of the switch is less than 0.2 dB up to 15 GHz and the isolation is higher than 20 dB up to 25 GHz. An RF model of the switches is used to analyse the effects of the switch design parameters and RF performance. The optimization of the switch mechanical design is discussed where the threshold voltage can be lower than 25 V. The lateral switches are fabricated by deep reactive ion etching (DRIE) process on a silicon-on-insulator (SOI) wafer with shadow mask technology.

https://nocweba.ntu.edu.sg/laq_mems/journal%20papers/2005/Low-loss%20lateral%20micromachined%20switches%20with%20frequencies%20from%20DC%20to%2025%20GHz.pdf

Low-loss lateral micromachined switches for high frequency applications

RF MEMS switches for power applications are discussed in this paper. Mechanical and electromagnetic simulations of a new switch type for power applications are presented, and fabrication aspects are discussed.

RF-MEMS switching concepts for high power applications

A single-pole-double-throw (SPDT) switch based on the toggle switch, a new type of radio frequency (RF) microelectromechanical (MEMS) switch structure for low voltage actuation, high broadband application and enhanced power capability, is presented. Electromagnetic simulation results are discussed and the fabrication process and measurement results are given. The SPDT switch exhibits low insertion loss ( 28 dB at 30 GHz).

Single-pole-double-throw switch based on toggle switch

A new type of RF MEMS switch for power applications using a push-pull concept is described. The switching element consist of a cantilever which is fixed by a suspension spring to the ground of the coplanar lines. The switching voltages are 30 V to close and 35 V to open. The switches exhibit low loss (<0.2 dB at 27 GHz) with good isolation (20 dB at 27 GHz).

Toggle-switch - a new type of RF MEMS switch for power applications

A new type of RF MEMS switch for low voltage actuation, high broadband application and high power capability is presented. Mechanical and electromagnetic simulations of this new RF MEMS switch type are shown and the fabrication process and measurement results are given. The switching element consists of a cantilever which is fixed by a suspension spring to the ground of the coplanar line. The closing voltage is 16V. The switches exhibit low insertion loss ( 22dB@30GHz).

A New Type of High Bandwidth RF MEMS Switch - Toggle Switch

RF MEMS switches have improved electromagnetic properties compared to solid-state switches. Therefore, these devices are a promising alternative. Various designs have been studied, which show lower insertion loss in closed state (0.25 dB at 35 GHz), high isolation in open state (>14 dB at 30 GHz) and allow high power handling (>2.5 W at 5 GHz). Reliability and life-time are critical parameters of these new structures and little data are available today. This authors report on reliability and power handling investigations of the recently developed toggle switch, an ohmic contact switch. More than 2.4×105 switch cycles were successfully performed, the measured switch time was 12 μs and the release time was 25 μs. Contact resistances in the range of 5–16 ohm were measured and a temperature dependency of the pull-in voltage of −0.3 V/deg was observed.

W. Simon

Papers

RF-MEMS switching concepts for high power applications

Single-pole-double-throw switch based on toggle switch

Toggle-switch - a new type of RF MEMS switch for power applications

A New Type of High Bandwidth RF MEMS Switch - Toggle Switch

Toggle switch: investigations of an RF MEMS switch for power applications