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Proceedings ArticleDOI

One bit distributed X-band phase shifter design based on RFMEMS switches

01 Dec 2007-pp 725-728
TL;DR: In this paper, the phase shift of a one-bit low-loss X-band phase shifter based on MEMS capacitors is described, which shows a phase shift ratio of 90 degrees at 7.5 GHz, 135 degrees at 11.4 GHz and 180 degrees at 15 GHz with applied bias of 33.24 V. The insertion losses are less than 0.2 dB and return losses are more than 14 dB over the desirable frequency ranges from 0 to 16 GHz.
Abstract: This article describes the design of a one- bit low-loss X-band phase shifter based on MEMS capacitors. The phase shifter shows a phase shift of 90deg at 7.5 GHz, 135deg at 11.4 GHz and 180deg at 15 GHz with applied bias of 33.24 V. The insertion losses are less than 0.2 dB and return losses are more than 14 dB over the desirable frequency ranges from 0 to 16 GHz. Total length of 12 MEMS bridges phase shifter is 2.83 mm. At 7.5 GHz, the phase shift per unit length is 31.8deg/mm, 47.7deg/mm at 11.4 GHz and 63.6deg/mm at 15 GHz showing very large phase shift per length.
References
More filters
Journal ArticleDOI
TL;DR: In this paper, a coplanar waveguide (CPW) transmission line with fixed-fixed beam MEMS bridge capacitors placed periodically over the transmission line, thus creating a slow-wave structure was designed.
Abstract: Wide-band switches and true-time delay (TTD) phase shifters have been developed using distributed microelectromechanical system (MEMS) transmission lines for applications in phased-array and communication systems. The design consists of a coplanar waveguide (CPW) transmission line (W=G=100 /spl mu/m) fabricated on a 500 /spl mu/m quartz substrate with fixed-fixed beam MEMS bridge capacitors placed periodically over the transmission line, thus creating a slow-wave structure. A single analog control voltage applied to the center conductor of the CPW line can vary the phase velocity of the loaded line by pulling down on the MEMS bridges to increase the distributed capacitive loading. The resulting change in the phase velocity yields a TTD phase shift. Alternatively, the control voltage can be increased beyond the pull-down voltage of the MEMS bridges such that the capacitive loading greatly increases and shorts the line to ground. The measured results demonstrate 0-60 GHz TTD phase shifters with 2 dB loss/118/spl deg/ phase shift at 60 GHz (/spl sim/4.5-ps TTD) and 1.8 dB loss/84/spl deg/ phase shift at 40 GHz. Also, switches have been demonstrated with an isolation of better than 40 dB from 21 to 40 and 40 to 60 GHz. In addition, a transmission-line model has been developed, which results in very close agreement with the measured data for both the phase shifters and switches. The pull-down voltage is 10-23 V, depending on the residual stress in the MEMS bridge. To our knowledge, this paper presents the first wide-band TTD MEMS phase shifters and wide-band switches to date.

440 citations

Journal ArticleDOI
TL;DR: In this article, the design, fabrication, and testing of a low-actuation voltage Microelectromechanical systems (MEMS) switch for high-frequency applications is described.
Abstract: This paper reports on the design, fabrication, and testing of a low-actuation voltage Microelectromechanical systems (MEMS) switch for high-frequency applications. The mechanical design of low spring-constant folded-suspension beams is presented first, and switches using these beams are demonstrated with measured actuation voltages of as low as 6 V. Furthermore, common nonidealities such as residual in-plane and gradient stress, as well as down-state stiction problems are addressed, and possible solutions are discussed. Finally, both experimental and theoretical data for the dynamic behavior of these devices are presented. The results of this paper clearly underline the need of an integrated design approach for the development of ultra low-voltage RF MEMS switches.

274 citations


"One bit distributed X-band phase sh..." refers background in this paper

  • ...However, the measured values may differ from 50 -300% [3, 5] due to the in-built stress in the membrane....

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  • ...Kz can be expressed in terms of the meander dimensions and material properties and is given in [5]....

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  • ...bridges as follows [5]: ) 1 ( 27 8 0 3 0 A g k V z p ε =...

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Journal ArticleDOI
TL;DR: In this paper, a symmetric toggle switch (STS) is proposed for 8-14 GHz applications with low actuation voltage and high isolation, for high power and reliability applications in telecommunication.
Abstract: In this paper, we present a new type of rf MEMS switch with low actuation voltage and high isolation, for high rf power and reliability applications in telecommunication. ‘Symmetric toggle switch’ (STS) is based on push–pull mechanism and utilizes torsion springs and levers, placed symmetrically and transverse to CPW line. The switches designed for 8–14 GHz applications have analytically calculated and FEM simulated actuation voltages in the range of 8–10 V. The simulated insertion loss and isolation for the devices are 0.25 and 35 dB, respectively, at 10 GHz. The fabrication process and preliminary experimental results are also presented.

66 citations

Journal ArticleDOI
TL;DR: In this article, a 2-bit distributed coplanar-waveguide (CPW) phase shifter was developed for X-band operation based on distributed MEMS transmission line (DMTL) loaded with MEMS bridges and MIM capacitors.
Abstract: A wideband distributed coplanar-waveguide (CPW) phase shifter has been developed for X-band operation The design is based on the distributed MEMS transmission line (DMTL) loaded with MEMS bridges and MIM capacitors A 2-bit distributed phase shifter was fabricated on a 500-/spl mu/m quartz substrate, and achieved a true-time delay operation from 1 to 20 GHz with a reflection coefficient less than -11 dB from 2 to 20 GHz and above Insertion loss is dominated by a low-Q MIM capacitor (14 at 10 GHz) and the effect of this Q is shown, Increasing the MIM capacitor Q will result in an excellent 2-bit phase shifter with wideband performance at X-band frequencies

65 citations


Additional excerpts

  • ...Recently, several configurations have been reported to implement multi-bit phase shifters based on MEMS switching devices [2]....

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Journal ArticleDOI
TL;DR: In this paper, the authors presented a model which describes the stage circuit of DMTL phase shifter at the Ka band and an approach for DMTTL design utilizing the saw-shaped coplanar waveguide (CPW).
Abstract: The paper presents a model which describes the stage circuit of Distributed MEMS Transmission Line (DMTL) phase shifter at Ka band and an approach for DMTL design utilizing the saw-shaped coplanar waveguide(CPW). The result of circuit simulation and full wave analysis prove that the model is in good agreement with theoretical analysis. The model can effectively simplify the design complexity after optimization. Simulation results show that the S11 and S21 can achieve -20 dB and -2.5 dB, respectively, and the phase shift arrives at −180 ◦ at Ka band. Comparing with literature data, it has been predicted that S11 improves about 8 dB and the phase shift can increase about 100 ◦ in the same condition.

3 citations


"One bit distributed X-band phase sh..." refers methods in this paper

  • ...By utilizing MEMS switch to replace p-i-n diode or FET switch of conventional loaded line phase shifters, the insertion loss at high frequencies can be reduced effectively [1]....

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