Motorola MEMS switch technology for high frequency applications

As a powerful method to reduce actuation voltage in an electrostatic micro-actuator, we propose and investigate an electrostatic micro-actuator with a pre-charged series capacitor. In contrast to a conventional electrostatic actuator, the injected pre-charges into the series capacitor can freely modulate the pull-in voltage of the proposed actuator even after the completion of fabrication. The static characteristics of the proposed actuator were investigated by first developing analytical models based on a parallel-plate capacitor model. We then successfully designed and demonstrated a micro-switch with a pre-charged series capacitor. The pull-in voltage of the fabricated micro-switch was reduced from 65.4 to 0.6 V when pre-charged with 46.3 V. The on-resistance of the fabricated micro-switch was almost the same as the initial one, even when the device was pre-charged, which was demonstrated for the first time. All results from the analytical models, finite element method simulations, and measurements were in good agreement with deviations of less than 10%. This work can be favorably adapted to electrostatic micro-switches which need a low actuation voltage without noticeable degradation of performance.

Section: Introductionmentioning

confidence: 99%

Electrostatic micro-actuator with a pre-charged series capacitor: modeling, design, and demonstration

Yang

Han

Lee

et al. 2014

“…However, one of the most difficult problems for commercialization of the electrostatic actuators is their typical high actuation voltage of several tens of volts. Many research groups have concentrated on reducing the actuation voltage by decreasing the spring constant, increasing the overlap area, using a counter electrode to maximize the restoring force [12,13], or introducing a CMOS up-converter for amplifying the input voltage [14]. Nevertheless, there still have been many disadvantages, for instance, mechanical vulnerability, concomitant large area, an increasing number of bias-ports and additional power consumption.…”

Section: Introductionmentioning

confidence: 99%

Modeling, fabrication and demonstration of an electrostatic actuator with a coplanar pre-charged electrode

Yang

Choi

Lee

et al. 2011

We present the modeling, fabrication and measurement results of a novel electrostatic actuator with a coplanar pre-charged electrode. Different from the conventional electrostatic actuator, the pull-in voltage of the proposed actuator can be freely controlled even after fabrication by inducing charges prior to use in the auxiliary electrode right next to the actuation electrode. To investigate the static and dynamic characteristics of the proposed actuator, analytical models were first developed on the basis of a parallel-plate capacitor model. We then successfully designed, fabricated, and evaluated a micro-switch with a fixed–fixed beam and a coplanar pre-charged electrode. By properly introducing a dimple structure, the pull-in voltage of the fabricated micro-switch was reduced from 71.2 V to 6.8 V when pre-charged by 58.8 V. The resonant frequency of the fabricated micro-switch was 84.8% of the initial resonant frequency when the reduced pull-in voltage of the device was half of the original pull-in voltage. These measurement results were compared with those from the analytical models and FEM simulation, showing deviations of less than 12%. This work can favorably be adapted and used in designing an electrostatic micro-switch since the proposed switch can remarkably reduce the pull-in voltage as desired without notable performance degradation.

“…Their advantages, such as excellent RF performances up to microwave frequencies range, linearity and very low power consumption, make them a serious alternative to usual semiconductor technologies for switches like PIN diodes or field effect transistors (FET) [1]. Most of the fabricated RF-MEMS switches are based on a clamped-clamped beam [2] or on a cantilever beam [3], notwithstanding some works showing complex designs [4,5]. As clamped-clamped beams and cantilever beams are widely used, they have been studied many times, thus leading to many papers presenting analytical models.…”

Section: Introductionmentioning

confidence: 99%

Simulation and optimization of a totally free flexible RF MEMS switch

Lorphelin¹,

Robin²,

Rollier³

et al. 2009

This paper presents the principle and the modeling of an innovative RF MEMS switch designed for low voltage applications, especially for mobile phones. This switch is based on a totally free flexible membrane, which is supported by pillars and actuated electrostatically by two pairs of electrodes, enabling two forced states. The main advantage of this structure is the use of a lever effect in order to provide high deflections above the transmission line even with a small gap, which explains why the actuation voltage is small compared to classical MEMS switches. The Euler-Bernoulli beam theory is applied to build an analytical 1D model with boundary conditions, which depend on the type of actuation and if pull-in is reached or not. This model is discretized and solved by the finite difference method. Then, a more accurate 3D finite element method is applied to add corrections to the first model. Once this modeling approach is validated, it is used to determine adequate geometrical parameters for the desired switch specifications. Mechanical characterizations on processed components show a pull-in voltage about 7.5 V, which is in good agreement with simulated values. RF measurements show excellent performances.