Performance of low-loss RF MEMS capacitive switches

Abstract

This letter details the construction and performance of metal membrane radio frequency MEMS switches at microwave and millimeter-wave frequencies. These shunt switches possess a movable metal membrane which pulls down onto a metal/dielectric sandwich to form a capacitive switch. These switches exhibit low loss (< < <0.25 dB at 35 GHz) with good isolation (35 dB at 35 GHz). These devices possess on-off capacitance ratios in the range of 80-110 with a cutoff frequency (figure of merit) in excess of 9000 GHz, significantly better than that achievable with electronic switching devices.

Phase Noise Analysis of MEMS-Based Phase Shifters

“…2. The switch could be the standard capacitive shunt design developed by Raytheon with a center pull-down electrode [2], or the DC-contact shunt switch with two pull-down electrodes developed by Muldavin et al [12], and Feng et al [13]. Alternatively, it could also be a low spring-constant switch (Pacheco et al [4]).…”

“…(2,4) are used, the phase noise relative to the carrier due to the reflection from the MEMS series switch becomes:…”

“…Micro-electromechanical (MEMS) series and shunt switches have been recently used in many low-loss phase shifters circuits [1], [2], [3], [4], [5], [6]. The MEMS phase shifters are typically implemented using standard PIN diode or FET switch designs, except that the switching element is replaced by a MEMS switch.…”

A comparison between RF MEMS switches and semiconductor switches

“…al. [6] because the signal lines are also part of the electrostatic actuator. It has also been found that a metal-to-insulator mechanical contact can be more reliable than a metal-to-metal contact and hence switches are made that are variable capacitors.…”

“…Over that time MEMS devices have become a focus for research in microwave switches [4][5][6]. For a review of RF MEMS devices see [7].…”