A micromachined RF low phase noise voltage-controlled oscillator for wireless communications

Young, Darrin J.; Boser, Bernhard E.; Malba, Vincent; Bernhardt, Anthony F.

doi:10.1002/mmce.1037

Cited by 30 publications

(37 citation statements)

References 17 publications

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“…In general, the tunability of carbon based varactors, similar to MEMS parallel plate varactors, is inherently limited compared to capacitance ratio of 4-6 of standard solid-state varactors. 37 However, voltage-controlled oscillators 108,109 and tunable filters 110 have already been demonstrated using the limited tunability of MEMS varactors which show a promise for possible application of the carbon based varactor.…”

Section: B Tunability and Parasitic Capacitancesmentioning

confidence: 99%

Vertically aligned carbon based varactors

Ghavanini

Enoksson

Bengtsson

et al. 2011

Journal of Applied Physics

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This paper gives an assessment of vertically aligned carbon based varactors and validates their potential for future applications. The varactors discussed here are nanoelectromechanical devices which are based on either vertically aligned carbon nanofibers or vertically aligned carbon nanotube arrays. A generic analytical model for parallel plate nanoelectromechanical varactors based on previous works is developed and is used to formulate a universal expression for their voltage-capacitance relation. Specific expressions for the nanofiber based and the nanotube based varactors are then derived separately from the generic model. This paper also provides a detailed review on the fabrication of carbon based varactors and pays special attention to the challenges in realizing such devices. Finally, the performance of the carbon based varactor is assessed in accordance with four criteria: the static capacitance, the tuning ratio, the quality factor, and the operating voltage. Although the reported performance is still far inferior to other varactor technologies, our prognosis which stems from the analytical model shows a promise of a high quality factor as well as a potential for high power handling for carbon based varactors.

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Section: B Tunability and Parasitic Capacitancesmentioning

confidence: 99%

Vertically aligned carbon based varactors

Ghavanini

Enoksson

Bengtsson

et al. 2011

Journal of Applied Physics

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“…The implementation of these devices is in low noise power amplifiers, matching networks, and monolithic lownoise VCO is an attractive proposition. In fact, the quality factor of these components ultimately determines the phase noise performance, which is critical in high performance communication systems [1]. The introduction of MEMS in RF systems increases the functionality and improves the performance.…”

Section: Introductionmentioning

confidence: 99%

Low phase noise performance of VCO using MEMS

Al-Khateeb

Subki

2008

2008 International Conference on Computer and Communication Engineering

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The paper presents a monolithic voltage controlled oscillator (VCO) prototype designed with microelectro-mechanical systems (MEMS) devices. It achieves the stringent performance requirements of various wireless communication applications such as GSM cellular telephony. The VCO meets the low phase noise requirement of -136 dBc/Hz at large offset frequency (3MHz) over the appropriate frequency range. A model for the simulation of the monolithic VCO is proposed. A suitable topology for the model is the Colpitts Oscillator. It is relatively less complicated, which facilitates the practical integration of the LC components. The main components in the configuration are the MEMS variable capacitor and monolithic 3-D coil inductor. These components are suitable for low phase-noise and low power consumption at the application frequencies.

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“…Young and Boser (1997) were the first to develop a surface micro-machined varactor for VCO application. Dec and Suyama (1998) developed twoplate and three-plate varactors in polysilicon micromachining process and used it in VCO circuits.…”

Section: Introductionmentioning

confidence: 99%

A top-down design methodology of MEMS varactor for RF applications based on a substrate-induced capacitive model

2011

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Due to their excellent quality factor in microwave frequency range, microelectromechanical (MEMS) varactors are an attractive choice for wireless communication engineers for building high performance telecommunication circuits. Significant progress in the technology of MEMS varactor has been reported over the past few years; however a comprehensive design methodology for the varactors based on some performance specifications is not reported. Also, it has been found that for the varactors fabricated with multi user processes (MUMPs), the measured capacitance deviates widely from the predicted value. In this work, it has been shown that a substrateinduced capacitance can change the expected capacitance of the varactor widely and can justify the deviation of the measured values to a good degree of accuracy. Here, a quantitative account of this difference has been presented. The capacitance profile of the varactor fabricated in PolyMUMPs process has been measured and the results show good agreement with the design values; thus indicating a clear influence of substrate induced capacitance on the varactor. Finally, a systematic design methodology of the varactor for a voltage controlled oscillator (VCO) application has been given.

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A micromachined RF low phase noise voltage-controlled oscillator for wireless communications

Cited by 30 publications

References 17 publications

Vertically aligned carbon based varactors

Vertically aligned carbon based varactors

Low phase noise performance of VCO using MEMS

A top-down design methodology of MEMS varactor for RF applications based on a substrate-induced capacitive model

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