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This paper presents the modeling, manufacturing, and testing of a micro-electromechanical system (MEMS)-based LC tank resonator suitable for low phase-noise voltage-controlled oscillators (VCOs). The device is based on a variable MEMS varactor in series with an inductive coplanar waveguide line. Two additional parallel stubs controlled by two ohmic MEMS switches have been introduced in order to increase the resonator tunability. The device was fabricated using the FBK-irst MEMS process on high resistivity (HR) silicon substrate. Samples were manufactured with and without a 0-level quartz cap. The radio frequency characterization of the devices without 0-level cap has shown a continuous tuning range of 11.7% and a quality factor in the range of 33–38. The repeatability was also tested on four samples and the continuous tuning is 11.7 ± 2%. Experimental results on the device with a 0-level cap, show a frequency downshift of about 200 MHz and a degradation of the quality factor of about 20%. This is, most likely, due to the polymeric sealing ring as well as to a contamination of the ohmic contacts introduced by the capping procedure. A preliminary design of a MEMS-based VCO was performed using Advanced Design System and a hardwired prototype was fabricated on Surface Mount Technology on RO4350 laminate. The prototype was tested resulting in a resonance frequency of 5 GHz with a phase noise of −105 and −126 dBc at 100 KHz and 1 MHz, respectively, and a measured output power of −1 dBm.

This paper presents the modeling, simulations, and measurements of a compact multiband microelectromechanical (MEMS)‐based LC tank resonator suitable for low phase noise voltage‐controlled oscillators (VCOs). The resonator is based on a high‐Q spiral inductor and high capacitance ratio varicap fully integrated in FBK‐irst (Fondazione Bruno Kessler) MEMS manufacturing process. The design of the varicap is based on double‐actuation mechanism with a mechanical central bond that inhibits the pull‐in allowing for a theoretically infinite tuning ratio. The measurements have shown a total not continuous capacitance ratio (Cr) of 5.2 with a continuous variation of the capacitance values in the range 225 fF–600 fF which corresponds to a continuous capacitance ratio (Cr*) of 2.6. The performance repeatability, the power‐handling capability, and the stability over time were tested on 10 samples showing a negligible variation of the capacitance values. The spiral inductor consists of a suspended gold membrane thick 5 µm in a circular shape which was modeled in order to optimize the quality factor (Q) in the frequency range 2–4 GHz. The measurement results show a Q of about 55 in the 2–4 GHz frequency band. The LC tank measurements show an overall tuning range better than of 45% in the 3.2–4.9 GHz frequency band, consisting of two continuous tuning ranges of 7.5% and 25%. The LC tank allowed the design of MEMS‐based voltage‐controlled oscillators (VCOs) with an overall tuning better than 60% in the frequency range 2.15 GHz–3.85 GHz and two separate regions of continuous tuning range. The VCO prototype will be fabricated on Surface Mount Technology on RO4350 laminate. The main figures of merit are presented in comparison with the state of the art.

The design of a 4-channel switched filter bank in the S-, C-band using PIN diode switches is described. Narrow band (3.2-3.5%) filters are designed on suspended substrate stripline. The biasing circuit allows the switches to be driven with TTL-compatible voltages and minimum biasing current. The average insertion loss measured was 3.6 dB corresponding to a Q factor of 580. Spurious responses were suppressed from DC to roughly 19 GHz.