Design and Fabrication of a Ka Band RF MEMS Switch with High Capacitance Ratio and Low Actuation Voltage

In this paper a high capacitance ratio and low actuation voltage RF MEMS switch is designed and fabricated for Ka band RF front-ends application. The metal-insulator-metal (MIM) capacitors is employed on a signal line to improve the capacitance ratio, which will not degrade the switch reliability. To reduce the actuation voltage, a low spring constant bending folding beam and bilateral drop-down electrodes are designed in the MEMS switch. The paper analyzes the switch pull-in model and deduces the elastic coefficient calculation equation, which is consistent with the simulation results. The measured results indicated that, for the proposed MEMS switch with a gap of 2 μm, the insertion loss is better than −0.5 dB and the isolation is more than −20 dB from 25 to 35 GHz with an actuation voltage of 15.8 V. From the fitted results, the up-state capacitance is 6.5 fF, down-state capacitance is 4.3 pF, and capacitance ratios is 162. Compared with traditional MEMS capacitive switches with dielectric material Si3N4, the proposed MEMS switch exhibits high on/off capacitance ratios of 162 and low actuation voltage.

Gate Capacitance and Off-State Characteristics of E-Mode p-GaN Gate AlGaN/GaN High-Electron-Mobility Transistors After Gate Stress Bias

This study investigated the gate capacitance and off-state characteristics of 650-V enhancement-mode p-GaN gate AlGaN/GaN high-electron-mobility transistors after various degrees of gate stress bias. A significant change was observed in the on-state capacitance when the gate stress bias was greater than 6 V. The corresponding threshold voltage exhibited a positive shift at low gate stress and a negative shift when the gate stress was greater than 6 V, which agreed with the shift observation from the I–V measurement. Moreover, the off-state leakage current increased significantly after the gate stress exceeded 6 V during the off-state characterization although the devices could be biased up to 1000 V without breakdown. The increase in the off-state leakage current would lead to higher power loss.

Bandwidth Improvement of MMIC Single-Pole-Double-Throw Passive HEMT Switches with Radial Stubs in Impedance-Transformation Networks

In this paper, we propose a new configuration for improving the isolation bandwidth of MMIC single-pole-double-throw (SPDT) passive high-electron-mobility transistor (HEMT) switches operating at millimeter frequency range. While the conventional configuration adopted open-stub loading for compensation of the off-state capacitance, radial stubs were introduced in our approach to improve the operational bandwidth of the SPDT switch. Implemented in 0.15 m GaAs pHEMT technology, the proposed configuration exhibited a measured insertion loss of less than 2.5 dB with better than 30 dB isolation level over the frequency range from 33 GHz to 44 GHz. In terms of the bandwidth of operation, the proposed configuration achieved a fractional bandwidth of 28.5% compared to that of 12.3% for the conventional approach. Such superior bandwidth performance is mainly attributed to the less frequency dependent nature of the radial stubs.

Design and Analysis of Shunt Configuration-Based RF MEMS Switch

In this paper a shunt type RF MEMS switch design and analysis for tunable applications is presented. Switch works based on the electrostatic actuation principle. Theoretical calculated Switch parameters are compared with the electromechanical and electromagnetic simulation results. The effect of various materials like conductor and dielectrics & parameters like airgap, beam width on the electromechanical parameters of the switch is analyzed to get low pull-in voltage, high switching speed, better capacitance ratio, return loss, insertion loss, and isolation loss. The switch up and down state capacitance are 40.9fF and 4.45pF respectively. Down to up state capacitance ratio of this switch is 108.69. The designed switch has an actuation voltage of 32V. RF performance is simulated from 1-10GHz. In ON state switch has return loss of -35dB, insertion loss of -0.1dB. In the OFF-state switch has return loss of -1dB and an isolation loss of -11dB.

Charge carrier dynamics in tantalum oxide overlayered and tantalum doped hematite photoanodes

The effects that Ta2O5-overlayer and Ta-doping have on the photoelectrochemical performance and surface state capacitance of hematite photoanodes.

A four-state capacitance molecular switch based on a redox active tetrathiafulvalene self-assembled monolayer

A tetrathiafulvalene self-assembled monolayer has been successfully exploited as a 4-state electrochemical switch using the capacitance as output signal.