A miniaturized reconfigurable broadband attenuator based on RF MEMS switches

Abstract

Reconfigurable attenuators are widely used in microwave measurement instruments. Development of miniaturized attenuation devices with high precision and broadband performance is required for state-of-the-art applications. In this paper, a compact 3-bit microwave attenuator based on radio frequency micro-electro-mechanical system (RF MEMS) switches and polysilicon attenuation modules is presented. The device comprises 12 ohmic contact MEMS switches, π-type polysilicon resistive attenuation modules and microwave compensate structures. Special attention was paid to the design of the resistive network, compensate structures and system simulation. The device was fabricated using micromachining processes compatible with traditional integrated circuit fabrication processes. The reconfigurable attenuator integrated with RF MEMS switches and resistive attenuation modules was successfully fabricated with dimensions of 2.45 × 4.34 × 0.5 mm3, which is 1/1000th of the size of a conventional step attenuator. The measured RF performance revealed that the attenuator provides 10–70 dB attenuation at 10 dB intervals from 0.1–20 GHz with an accuracy better than ±1.88 dB at 60 dB and an error of less than 2.22 dB at 10 dB. The return loss of each state of the 3-bit attenuator was better than 11.95 dB (VSWR < 1.71) over the entire operating band.

Wafer-Level Packaging Method for RF MEMS Applications Using Pre-Patterned BCB Polymer

“…To illustrate the feasibility of this packaging method and to explore the impact of this process on the RF and reliability performance of the RF MEMS devices with movable structures, the application of this approach for a RF MEMS switch was implemented and tested. A series of high performance RF MEMS switches with Au-Au contacts, which were described in an earlier work [ 21 ], are packaged through the pre-patterned BCB packaging process in a wafer level. Figure 12 shows this series switch consisting of a movable gold cantilever, which is suspended above the actuation plate and mechanically anchored to the signal line of the CPW.…”

Scalable Contact-Capacitive MEMS Switches With High Capacitance Ratio for Millimeter-Wave Applications

“…The switches are fabricated by the Tsinghua University metal-contact switch process [21][22] as shown in Fig. 7.…”

A comprehensive overview of recent developments in RF-MEMS technology-based high-performance passive components for applications in the 5G and future telecommunications scenarios

“…Substantially new contributions appeared only in the last half decade with [95][96], both proposing 3-bit attenuators enclosed in CPW configuration and demonstrated up to 20 GHz.…”

“…In a similar way, [95] unloaded branch or to a branch loaded with π-shaped resistive network by its SPST switch. Specular SPST switches and T-junction complete the sub-unit.…”