One main obstacle that reduces the yield in RF MEMS technology is the variation of the residual stress resulting from
fabrication. Residual stress can occur across the wafer, from the wafer to another wafer, or from one batch of fabrication
to another one, and is more pronounced in cantilever bean type switches. For the present paper we have used new sets of
dimples to reduce the sensitivity of the structure to the stress level. The SEM pictures of the proposed configuration and
those of the conventional beam switch fabricated on the same wafer are analyzed sufficiently. The comparison amply
proves soundness of our method. The high actuation voltage is another main issue that requires considerable
investigation, and is generally higher in clamped-clamped beam type switches. In order to reduce the actuation voltage,
we have designed, fabricated and tested several configurations with different supporting beams. The actuation voltage of
as low as 10 volts is achieved and all switches exhibit excellent RF performance. At 40GHz the insertion loss of the
switches varies ranging from 0.35dB to 0.7dB. It is evident that at a lower frequency ranges this becomes even better. At
40GHz, the return loss for all switches measured -24dB. Lastly, isolation is better than 20dB to 30dB for all the
frequency band of interest.
In the analysis and modeling of MEMS devices, a general finite element formulation is necessary to solve a multidisciplinary
domain of the device with large number of nodes and elements.
In this paper, we present a step by step finite element formulation for automated modeling of multi-disciplinary domains.
The electro-thermo-mechanical domain is explained and an algorithmic approach for sequential analysis of an arbitrary
ground structure with multi-disciplinary boundaries is developed and implemented in Matlab with a graphical user
interface. The results of the finite element approach is compared and verified with exact solutions and test results from
literature. The agreement of results verifies the application of proposed finite element formulation to the analysis of
This formulation provides a fast and reliable tool to analyze electro-thermo-elastic devices which allows large flexibility
in the selection of mechanical and electrical boundary conditions.
Continues-wave photomixing phenomenon in ultra-fast photoconductors
and high-temperature superconductors (HTS) is studied and photomixing efficiencies of these materials are investigated.
Photocurrent distributions in both photoconductor and superconductor
based photomixers are calculated and their common characteristics
are compared in detail.
A new CW photoconductive integrated photomixer/antenna THz source is presented. A THz signal is generated in the DC-biased photoconductive strip by employing optical heterodyne photomixing, and at the same time the size of the photoconductive strip on the grounded dielectric substrate is designed to have an efficient broadside radiation. Analytical expressions for the photo-induced current as well as the radiation power are calculated in detail, which make it possible to evaluate the performance of the structure made by different photoconductive materials. The typical μW output power can be obtained by mW laser pump power for frequencies up to 1 THz.
This paper addresses the use of RF MEMS devices in wireless and satellite communication systems. It describes the MEMS actuators typically needed for such devices. Novel configurations are presented for MEMS variable capacitors, MEMS tunable inductors and RF MEMS mutiport switches. The tuning range of the variable capacitor was measured and found to be 280%, which far exceeds that of the traditional parallel plate MEMS variable capacitors. The MEMS tunable inductor is realized using MEMS fixed inductors, capacitors and a variable MEMS capacitor. The proposed MEMS multiport switch has demonstrated a superior RF performance up to 20 GHz.