Ming-xin Song

Design and analysis of a novel low actuation voltage capacitive RF MEMS switches

The novel design of capacitive RF MEMS switches using torsion spring is presented and analyzed in this paper. The RF MEMS switches not only have ordinary folded suspending beams, but also add torsion springs. The simulation results show that compared with ordinary bending deflection, the torsion deflection is sensibly influenced by the ratio of the arm width (b) and the arm thickness (t), so the actuation voltage (VT) of the RF MEMS capacitive switches which have both the ordinary bending deflection and added torsion deflection will be obviously depressed. At same time, the theory analysis shows that the lower VT can be obtained with longer torsion arm length (LD), longer driven arm length (LD).By optimizing the structure design of RF MEMS switches, when LT, LD, b and t are 180 um, 120 um, 5 um and 1 um, respectively, the area actuation electrodes is 120times120 um2, the actuation voltages of RF MEMS switches is 1.5 V by computer simulating.

Wafer Level Micropackaging for Distributed MEMS Phase Shifters

A novel packaging structure which is performed using wafer level micropackaging on the thin silicon substrate as the distributed MEMS phase shifters wafer with vertical feedthrough is presented. The RF performances of proposed structure are investigated using Microwave Studio (CST). The results show that the insertion loss (S21) and return loss (S11) was -0.4-1.84 dB and under -10 dB at 1-50 GHz. respectively. And especially, the phase shifts of 360deg are obtained at 48 GHz. Tins indicate that the proposed packaging structure for the distributed MEMS phase shifters can provide the maximum amount of phase shift with the minimum amount of insertion loss and with return loss of less than -10 dB.

Influence of Wafer Level Packaging Modes on RF Performance of MEMS Phase Shifters

With RF MEMS technology rapid development, the distributed RF MEMS phase shifters have exhibited excellent RF performance, such as high isolation, high phase shifts, low insertion loss and wide bandwidth operation features at high frequency. However, the applications of RF MEMS phase shifter are hampered by the lack of production-worthy wafer level packaging. Therefore, the problems on packaging solved are very stringent. This paper mainly investigates on the influence of wafer level packaging modes on the RF performance of distributed RF MEMS phase shifters. The insertion loss S21, return loss S11 and phase shifts parameters are analyzed using 3D electromagnetic simulation tool - microwave studio (CST). Simulation results show that the insertion loss of the distributed RF MEMS phase shifters for bonding wafer packaging and wafer level micropackaging is -0.59dB and -0.061dB at l0GHz, -0.79dB and -0.25dB at 50 GHz, respectively. The return loss -11.8366dB and -26.66906dB at l0GHz, -14.50227dB and -32.30596dB at 50GHz, and the phase shift is 170.78deg and 161.82deg at 50GHz, respectively. Therefore, we concluded that different wafer level packaging modes distinctly affect the microwave performance of the distributed RF MEMS phase shifters. Comparing the RF performance parameters of two modes, the wafer level micropackaging mode shows excellent RF performance (the average insertion loss of -0.ldB and the average return loss of deg22 dB) and no resonances at 1-60 GHz, and adapted to the packaging of distributed RF MEMS phase shifters

Numerical simulation and analysis of an electroactuated MEMS capacitive switch using finite element method

The MEMS capacitive switch based on fixed-fixed microbeam have garnered significant attention due to their geometric simplicity and broad applicability, and the accurate models should be developed to predict their electromechanical behaviors. The improved macromodel of the fixed-fixed microbeam of MEMS capacitive switch is presented in this paper, the numerical analysis of mechanical characterizations of the MEMS capacitive switches under electric actuation are performed by the finite element discretization method, and the performances of static and dynamic of MEMS capacitive switch are obtained. The numerical results show that, with only a few nodes used in the computation, the finite element discretization method gives the identical results to other numerical methods, such as the shooting method and experiments. Moreover, the proposed model can offer proper and convenient approach for numerical calculations, and promote design of MEMS devices.

Vibration investigation of clamped-clamped microbeam of MEMS capacitive switch under mechanical shock

A numerical analytical method based on multi-mode Galerkin discretization is presented to investigate the nonlinear response of the clamped-clamped microbeam of the MEMS capacitive switch under the different mechanical shock loads. The results show that using five or more modes can be sufficient to capture the nonlinear dynamic response of clamped-clamped microbeam, and the microbeam experiences a mechanical shock load as a quasi-static load or a dynamic load depending on the ration between the natural periods of the structure and the period or requency of the shock load. Moreover, the proposed method gives the identical results to other numerical methods in the literature, and is straightforward to implement and could save computation efforts while not losing accuracy.

The mechanical behavior investigation of MEMS switches for millimeter wave phase shifters

In this paper, a novel low spring constant hinge beam structure is presented in order to reduce the driven-voltage of switch. The mechanical behaviors of switches are investigated using the IntelliSuiteTM tool. The simulation results show that the driven voltage of 2.5V and the time response of 30us are obtained respectively. Moreover, the frequencies of all mechanical vibrant modes of beam are higher than 15 kHz.

Effects of Structure Parameters and Stress for Capacitive Switches MEMS Bridge on Time Response

In this paper, a novel method for analyzing the switching time of the electrostatic driven RF MEMS capacitive switches is presented. The effects of the structure parameters which mainly include the width, length and thickness and stress for capacitive switches MEMS bridge on time response are investigated using the SYNPLE module of IntelliSuitetrade tool. The result shows that the width of MEMS bridge and the stress in bridge indistinctively affect on time response, while the length and thickness of MEME bridge distinctively effect on time response.

Packaging and Feedthrough Modes of Wafer Level for RF MEMS Switches

This paper reports on the methods, feedthrough modes and RF performance of wafer level packaging for RF MEMS switches. By analyzing the effects of packaging methods and feedthrough modes on the cost, weight, size, loss, RF performance and function of switches, a novel wafer level packaging structure which is performed using the wafer-level microencapsulation on the thin silicon substrate as the RF MEMS switches wafer with the vertical feedthroughs is presented. This structure has some advantages, such as low thickness, low parasitic capacity, short electric path, lightweight, no real ring and compatibility with the devices fabrication processes. Therefore, for RF applications, the packaging structure obviously reduces electric path loss and fabrication cost, and provides better RF performance of RF MEMS switches

The Influence of the Chip-Scale-Package on the Functioning and Reliability of RF-MEMS Switches

This paper discusses the influence of materials and structures inside a package on the functioning and reliability of chip-scale-package RF-MEMS switches. It is shown that materials and structures strongly influence electrical performance characteristics such as the switching insertion loss of switches. By computer simulation design for a RF MEMS switches and its package, a model is built with choiceness performance characteristics. Especially, the pull-up electrode can increase reliability of the device, which has extremely low insertion loss of -0.8 dB and a high isolation of -33 dB up to 20 GHz. The packaging process can be applied to process wafer of RF MEMS switching devices. This work will help designers of RF-MEMS switches remove redundant features optimize structures in MEMS component packages to get maximize performance and help drive cost down

Investigation of Design and Vibration Modes of Low-Voltage Driven RF MEME Capacitive Switch for Millimeter Distributed Phase Shifter

This paper reports on design and analysis of electrostatic driven RF MEMS capacitive switches for radio-frequency (RF) applications. To reduce the driven voltage of MEMS switches, the mechanical designs of low spring-constant hinge shape beam structure are presented. The displacement distribution, driven voltage and mechanical vibration modes of the switch using the beam are analyzed by using IntelliSuitetrade software simulation tool for an optimization design, the results demonstrated that the driven voltage is lower than 2 V and the frequencies of all vibration modes are higher 12 kHz