King Yuk Chan

Scalable RF MEMS Switch Matrices: Methodology and Design

This paper proposes new solutions for implementing wideband large switch matrices. These solutions are based on crossbar and L-shaped topologies. This paper introduces a high-performance wideband switch cell to build up scalable NtimesN switch matrices and gives an account of the design, fabrication, and characteristics of the switch cell and a 3times3 crossbar switch matrix. The chosen design procedure is seen to be appropriate since it produces valid measured results. In addition, this paper presents an RF microelectromechanical systems L-shaped switch matrix, which indicates less variation of characteristics for certain types of connectivity. It also demonstrates that for a 4times4 switch matrix, there is a 50% improvement in insertion loss and phase-shift variation.

Monolithic crossbar MEMS switch matrix

This paper presents a novel approach to implement RF MEMS large size switch matrices. The concept is based on the implementation of a crossbar switch matrix and the introduction of unique switch cells that can be easily used to expand the matrix size. A six-mask fabrication process is adapted to fabricate the proposed four-port switch cell as well as the switch matrix samples. The switch cell has two operational states: thru and turn. This allows the cell to be easily integrated in the form of a crossbar switch matrix. Novel series contact cantilever beams have been used to implement the entire structure. The measured results for the entire switch cell show excellent insertion loss of 0.5dB, return loss of better than −20dB and isolation of −25dB for the thru path. The turn state of the switch shows a good performance of 0.4dB insertion loss, −18dB return loss and better than −25dB isolation for the frequency band of interest. A 3×3 switch matrix is implemented that shows 98% size reduction in comparison with the previously reported RF MEMS switch matrices.

RF MEMS Switchable Interdigital Bandpass Filter

By taking advantage of the MEMS contact type switches in tunable filters, a new method that allows both the adjustment of resonant frequency and the input/output and inter-resonator coupling is presented. A three-pole filter capable to switch to three different states is designed using this method. The measured center frequency for each state is 8, 9, and 10 GHz (25% tuning) with a constant bandwidth of around about 1 GHz. The measured insertion loss of the filter is better than 3.5 dB for all three states.

Novel Beam Design for Compact RF MEMS Series Switches

This paper presents two novel integrated RF MEMS series contact switches for broadband applications. The proposed designs are based on cantilever and clamped-clamped beams that can be easily integrated in large multi-port structures. A novel set of dimples are integrated in the cantilever type switch to prevent the unwanted warpage of the beam resulting from the residual stress of the fabrication process. The switches are fabricated using a metal based six-mask process. The results illustrate smooth beams with excellent RF performance. The cantilever beam switch shows an actuation voltage of 60 V with better than a 0.35 dB insertion loss and a 24 dB return loss up to 40 GHz. The isolation of the switch is 22 dB for all the frequency band of interest. The clamped-clamped beam switch results are also presented indicating enhanced isolation of 26 dB up to 40 GHz with 0.5 dB insertion loss.

Cantilever beam designs for RF MEMS switches

This paper presents the design, modeling, fabrication and measurements of two novel radio frequency microelectromechanical systems (RF MEMS) switches. Two new non-standard cantilever beams have been designed in order to validate the mathematical model developed for the calculation of the spring constant and to verify the fabrication parameters. The mechanical modeling is based on the Euler?Bernoulli beam equations. The fabricated switches using these cantilever beams exhibit 19 V and 23 V actuation voltages. The fabrication consists of a six-mask all-metal process. A unique dry-release technique is also described. The RF simulations and measurements of these switches are finally presented. The isolation is better than 23 dB and 27 dB and the return loss is better than 19 dB and 18 dB, from 0 to 40 GHz. The insertion loss is 1.15 dB and 1.3 dB for the two designs, respectively, for all frequency bands of interest.

A novel RF MEMS switch with novel mechanical structure modeling

A novel RF MEMS contact-type switch for RF and microwave applications is presented. The switch is designed with special mechanical structures for stiffness enhancement. A method of using dimple lines to reduce the stress sensitivity of a beam is shown with complete mathematical modeling and finite element mechanical simulation. A complete mathematical model is developed for the proposed switch. Limited fabrication resolution and non-uniformities in layer thickness and stress were taken into consideration for this design, concomitantly with the preservation of device miniaturization and functionalities. The novel mechanical modeling of the switch leads to the estimation of the actuation voltage and shows simplification from previously published analysis. The measured actuation voltage and RF performance of the novel RF MEMS switch are also reported. The switch actuated at 20 V achieved better than 22 dB return loss and less than 0.7 dB insertion loss in on state from dc–40 GHz; it provided better than 30 dB isolation in off state.

Substrate Integrated Waveguide H-Plane Horn Antenna With Improved Front-to-Back Ratio and Reduced Sidelobe Level

A cost-effective way of reducing sidelobe level and improving front-to-back ratio of the substrate integrated waveguide H-plane horn antennas is proposed in this letter. Metal rectangular patches and dielectric loading are integrated to the aperture of the horn antenna, resulting in an increased gain, narrow E-plane beamwidth, and reduced sidelobes and backward radiation. The overall dimensions of the fabricated antenna are 42 × 18.6 mm2 . The antenna works at 22.7 GHz with a measured gain of 10.1 dBi. A single substrate and a 3.5-mm connector with a transition pin are used to ensure the lowest cost for mass production.

RF-MEMS switches with new beam geometries: improvement of yield and lowering of actuation voltage

One main obstacle that reduces the yield in RF MEMS technology is the variation of the residual stress resulting from fabrication. Residual stress can occur across the wafer, from the wafer to another wafer, or from one batch of fabrication to another one, and is more pronounced in cantilever bean type switches. For the present paper we have used new sets of dimples to reduce the sensitivity of the structure to the stress level. The SEM pictures of the proposed configuration and those of the conventional beam switch fabricated on the same wafer are analyzed sufficiently. The comparison amply proves soundness of our method. The high actuation voltage is another main issue that requires considerable investigation, and is generally higher in clamped-clamped beam type switches. In order to reduce the actuation voltage, we have designed, fabricated and tested several configurations with different supporting beams. The actuation voltage of as low as 10 volts is achieved and all switches exhibit excellent RF performance. At 40GHz the insertion loss of the switches varies ranging from 0.35dB to 0.7dB. It is evident that at a lower frequency ranges this becomes even better. At 40GHz, the return loss for all switches measured -24dB. Lastly, isolation is better than 20dB to 30dB for all the frequency band of interest.

A beam steering single-arm rectangular spiral antenna with large azimuth space coverage

A novel beam steering single-arm rectangular spiral antenna operating at 3.3 GHz is analyzed using Ansys HFSS. There are 5 switches mounted on the spiral arm. If PIN diodes are used as switches, only one bias signal is required for actuation. Based on different operation of the switches, two cases with maximum beam directions spaced around 1500 in φ-plane are achieved. Both cases have maximum right hand circular polarization (RHCP) gain of approximately 5 dBi and meanwhile cross polarization is suppressed to a very low level. The variation with frequency of the maximum gain, maximum beam direction, and axial ratio is inspected. The proposed design has a 100-MHz bandwidth with good matching, stable maximum beam direction, maximum gain, and circular polarization purity for both cases.

Novel Miniaturized RF MEMS Staircase Switch Matrix

A novel implementation of wideband large switch matrices is proposed in this letter. The solution is based on staircase geometry. The approach demonstrates significant reduction in the number of control signal required compared to all existing RF MEMS switch matrix geometries, while maintaining the performance. This letter presents the design and characteristics of a semi-T switch cell and a 3 × 3 staircase switch matrix. The measurement of the switch matrix demonstrated excellent RF performance of maximum insertion loss of 2 dB, a return loss of better than 15 dB and an isolation higher than 40 dB for frequencies up to 40 GHz. To our knowledge, this is the first RF MEMS staircase switch matrix ever reported.