Title :
Digital-type RF MEMS switched capacitors
Author :
Rizk, J.B. ; Rebeiz, G.M.
Author_Institution :
Dept. of Electr. Eng. & Comput. Sci., Michigan Univ., Ann Arbor, MI, USA
Abstract :
This paper presents digital-type RF MEMS switched capacitors built in a coplanar waveguide (CPW) configuration. In this design, a MEMS shunt bridge is fabricated over an MIM capacitor. When the bridge is in the upstate position, the CPW line is loaded mainly by the up-state MEMS bridge capacitance. When the MEMS bridge is pulled down, the line is loaded by the MIM capacitor. As a result we obtain a digital-type switched capacitor suitable for 0.5-6 GHz operation. Switched capacitors of different values (300 fF, 600 fF, 750 fF, 1.5 pF, 2.25 pF) were fabricated and resulted in high-Q (>100) designs at 1 GHz. Also a 2-bit capacitor array was demonstrated. The values of Q are limited by metal-to-metal contact resistance (0.8 /spl Omega/) and the calibration accuracy of the method used.
Keywords :
MIM devices; Q-factor; UHF devices; coplanar waveguide components; micromechanical devices; microwave devices; varactors; 0.5 to 6 GHz; 0.8 ohm; 300 fF to 2.25 pF; CPW configuration; MEMS shunt bridge; MIM capacitor; RF MEMS switched capacitors; capacitor array; coplanar waveguide configuration; digital tunable matching networks; digital-type MEMS capacitors; fabrication process; high quality factor; metal-to-metal contact resistance; up-state MEMS bridge capacitance; varactors; Bridge circuits; Capacitance; Contact resistance; Coplanar waveguides; Dielectrics; Gold; MIM capacitors; Micromechanical devices; Radiofrequency microelectromechanical systems; Switches;
Conference_Titel :
Microwave Symposium Digest, 2002 IEEE MTT-S International
Conference_Location :
Seattle, WA, USA
Print_ISBN :
0-7803-7239-5
DOI :
10.1109/MWSYM.2002.1011876
