A frequency tunable half‐wave resonator using a MEMS variable capacitor

Abstract

A frequency tunable half‐wave resonator at 3 GHz is presented with a microelectromechanical systems (MEMS) variable capacitor as the tuning element. The capacitor is fabricated using the multi‐user MEMS process (MUMPs) technology provided by JDS/Cronos, and transferred to an alumina substrate by an in‐house developed flip‐chip process. This capacitor is electrostatically actuated. The resulting C‐V response is linear with a slope of 0.05 pF/V for a wide range of actuation voltages. The MEMS device has a capacitance ratio of 3:1 for 0‐70 V bias, with a Q‐factor of 140 measured at 1 GHz. A half‐wave tunable microstrip resonator with bias lines is designed to include this MEMS device, which exhibits linear tuning over 180 MHz (6 percent) centered around 3 GHz with a constant 3 dB bandwidth of 160 MHz over the entire tuning range. The power consumption of the MEMS device was measured to be negligible.

Thermo-mechanical evolution of multilayer thin films: Part I. Mechanical behavior of Au/Cr/Si microcantilevers

“…The lengthwise strain at the mid-plane, Z m , is given by Eq. (9). Lastly, the principle stress (x-direction) is given by Eq.…”

“…Most recently, Au/Cr/Si multilayer or "multimorph" structures have been utilized in micro-electro-mechanical systems (MEMS). Researched applications include: reflective optical structures such as mirrors [4], optical detectors [5], optical satellite navigation sensors [6], DC electrical relays and contacts [7], radio frequency (RF) components including switches [8] or variable capacitors [9], chemical [10] or biological [11] sensors, and vertical [12] or lateral [13] actuators. Study of Au/Cr/Si multimorphs may also help to understand the behavior of more basic structures, such as gold metallic traces, gold interconnect wire bond pads, or freestanding gold films.…”

Efficient X-band switched-mode microwave power amplifiers

“…Table 2 conveys in part the same message -the variations in parasitics due to hybrid integration and the variation in output capacitance of the different discrete devices produces a desired range of output impedances, Figure 7. A tuner is designed to cover this range and in the process of being implemented using MEMS varactors with a linear tuning range from 0.5-1.5pF [2]. The MEMS varactor is shown in Figure 8a, and the micro-machined 15-GHz 15-nH resonant frequency air inductor used for the selfassessment circuit and the bias lines for the PA in Figure 8b.…”

Hybrid RF-MEMS Switches Realized in SOI Wafers by Bulk Micromachining

“…This substrate transfer approach includes two types of MEMS switch fabrication process approaches. The first type is based on a surface micromachining process [15]- [17], [26], and the other is based on a bulk micromachining process [19]- [21]. The switch can be released before the transfer process, as in the case of UC Berkeley [26], or after the transfer process as in the case of Seoul National University [19] and Omron [20], [21].…”