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This letter presents a broadband microstrip-to-microstrip vertical transition. Basically, the transition is based on broadside coupling between the upper and lower microstrip patches through a wide slot etched on the ground plane. In order to enhance bandwidth of the transition, a patch introducing a half wavelength resonance into the passband is added on the ground plane. A demonstrator transition has been designed, fabricated and measured. Results show that a frequency range of 2.8 to 8.5 GHz (referred to return loss of 10 dB) is obtained.

This paper presents a wide band compact high isolation microelectromechanical systems (MEMS) switch implemented on a coplanar waveguide (CPW) with three ohmic switch cells, which is based on the series-shunt switch design. The ohmic switch shows a low intrinsic loss of 0.1 dB and an isolation of 24.8 dB at 6 GHz. The measured average pull-in voltage is 28 V and switching time is 47 μs. In order to shorten design period of the high isolation switch, a structure-based small-signal model for the 3-port ohmic MEMS switch is developed and parameters are extracted from the measured results. Then a high isolation switch has been developed where each 3-port ohmic MEMS switch is closely located. The agreement of the measured and modeled radio frequency (RF) performance demonstrates the validity of the electrical equivalent model. Measurements of the series-shunt switch indicate an outstanding isolation of more than 40 dB and a low insertion loss of 0.35 dB from DC to 12 GHz with total chip size of 1 mm × 1.2 mm.

Several through-silicon-substrate-via-holes used in microwave circuits are analyzed. The silicon via-holes have been fabricated by inductively coupled plasma (ICP) process. Using via-holes for microstrip transmission lines, a micromachined Ku-band interdigital filter has been designed, fabricated, and tested. It achieved an insertion loss of −2.4 dB, and a 3 dB fractional bandwidth of 8%. This filter has the advantages of small sizes and relatively outstanding RF performance.

A 3-bit microelectromechanical system (MEMS) digital attenuator is designed with 0–20 GHz bandwidth. The attenuation ranges from 0 to 35 dB with 5 dB step. The attenuator, with the coplanar waveguide (CPW), is implemented by surface sacrificial layer technology. The DC-contact MEMS switches with three contact dimples are symmetrically placed around the T type resistor network, making the switches minimum in number and the structure compact. Through the lumped parameter method, the attenuator has good terminal matches in different attenuation states. The test results show that eight different attenuation states are realized within 0–20 GHz. The attenuation deviation is less than ±5%, the insertion loss is less than 1.7 dB and the voltage standing wave rations is less than 1.4 under most of the attenuation states. With the MEMS switches and CPW being adopted, the attenuator has the advantages of higher linearity, lower insertion loss and power consumption. The chip size is about 3.2 mm2 including the pad.

This paper describes a novel monolithic switchable filter covering a bandpass frequency of 12–16 GHz at the Ku-band on a silicon substrate. The filter structure is based on parallel-coupled half-wavelength resonator topologies and microelectromechanical system-tunable resonators designed by placing ohmic switches at the open ends of the microstrip resonators. A wideband coplanar waveguide is designed for microstrip transition without via holes during wafer testing. The measured results show a minimum insertion loss of 3.6 dB, a return loss better than 15 dB, a 10.2% fractional bandwidth and a 14.2% tuning range from 13 to 15 GHz. The fabricated filter has a chip area of 15.1 mm × 3 mm and has achieved skirt slopes of over 30 dB GHz−1.