RF MEMS-based tunable filters

Abstract

This paper overviews the application of RF MEMS switches in tunable filters as well as circuit developments for bandpass filters covering 110 MHz to 2.8 GHz. RF MEMS have several desirable features, including small size, low power requirements, and low loss. The basic operation of Raytheon's RF MEMS capacitive membrane switch is described. An overview of the technique used to integrate the switch into a variable capacitor structure with sixteen capacitance states is provided. Variable capacitor structures are used to construct multipole lumped bandpass filter designs, each with sixteen states. Finally, measured data from two representative five-and six-pole bandpass filters are presented. Characterization data demonstrates that the insertion loss for the five-pole filter using on-chip inductors was between 6.6 and 7.3 dB, and between 3.7 and 4.2 dB for the six-pole filter using off-chip inductors.

Reconfigurable Microwave Filters

“…A bandpass filter with a center frequency tuning range from 110 MHz to 2.8 GHz has been reported in (Brank et al, 2001), the design uses capacitive switches to form variable capacitor banks to reconfigure center frequency, the device also uses metal insulator metal capacitors on the lumped topology. One of the filters in (Kim et al, 2006) uses a capacitive switch bank to reconfigure filter center frequency for wireless local area network applications.…”

Miniature and tunable millimeter-wave lowpass filter with MEMS switch

“…Recent developments in microelectromechanical systems (MEMS) have made possible the design of tunable filters and are expected to bring a new interest to these components [7][8][9][10]. Indeed, MEMS offer low losses, near-zero power consumption, and they can be monolithically integrated with conventional microwave integrated circuit (MIC) passive fabrication techniques.…”

High power nanocrystalline diamond RF MEMS- A combined look at mechanical and microwave properties

“…Due to their outstanding properties and excellent performance at high frequencies, RF MEMS devices have started replacing their solid state counterparts in filters [1], phase shifters [2] and antennas [3]. According to a 2006 market study, the global market for MEMS, with RF-MEMS being a major part will reach $12 billion by 2010 [4].…”