Supporting circuitry for a fully integrated micro electro mechanical (MEMS) oscillator in 45 nm CMOS technology

Abdelsalam, Mohamed Adel; Wahba, Mohammed; Abdelmoneum, M.A.; Duarte, D.; Ismail, Yehia

doi:10.1109/vlsisoc.2010.5642670

Cited by 4 publications

(2 citation statements)

References 14 publications

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“…However developing a MEMS resonator with high quality factor in MHz frequency ranges, which would be compatible with CMOS integrated circuits (Dragoi et al 2012) is very important in view of different applications. In integrated circuits, applications such as filters (Bannon et al 2000;Lopez et al 2009), timing and reference frequency devices (Lin et al 2004;Nguyen 2007), microprocessors (Abdelsalam et al 2010) and sensors such as pressure and humidity sensors (Shi et al 2013;Muniraj 2011) facing an important challenge either from scientific or engineering viewpoint that must be well addressed. As an important property, Quality factor (Q) is a scaled ratio between stored energy and damped energy per cycle, which is associated with frequency.…”

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Effects of slots on thermoelastic quality factor of a vertical beam MEMS resonator

Asadi

Sheikholeslami

2015

Microsyst Technol

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the resonance occurs in the mechanical domain. MEMS resonators have already started to use in various applications from wrist watches to the state of the art communications, due to their extremely features. However developing a MEMS resonator with high quality factor in MHz frequency ranges, which would be compatible with CMOS integrated circuits (Dragoi et al. 2012) is very important in view of different applications. In integrated circuits, applications such as filters (Bannon et al. 2000;Lopez et al. 2009), timing and reference frequency devices (Lin et al. 2004;Nguyen 2007), microprocessors (Abdelsalam et al. 2010) and sensors such as pressure and humidity sensors (Shi et al. 2013;Muniraj 2011) facing an important challenge either from scientific or engineering viewpoint that must be well addressed. As an important property, Quality factor (Q) is a scaled ratio between stored energy and damped energy per cycle, which is associated with frequency. In a MEMS resonator, Q is an indication of mechanical energy damping in the system that directly influences sensitivity and resolution of the device Hao et al. 2003). Theoretically, quality factor can be calculated for every frequency, whereas in practice, it is obtained for a specific resonance.In a beam type MEMS resonator, to understand and analyze the energy loss mechanisms, it is important to know the sources of energy loss. The latter could be consisted of support loss, thermoelastic loss and surface loss (Hao et al. 2003). Compression and decompression of an oscillating structure results an irreversible heat flow that is called thermoelastic damping (TED). In Clamped-Clamped (C-C) beam MEMS resonator, the beam in bending experiences a variation on temperature which causes a thermal gradient through the beam. The latter should be well adjusted to maintain the thermal equilibrium. To do this, energy must be intelligently dissipated while the quality factor of the Abstract Thermoelastic damping is one of the dominant mechanisms of structural damping in vacuum-operated microresonators. A three dimensional numerical model based on the finite element method is used for simulating thermoelastic damping in clamped-clamped microelectromechanical beam resonators. In this regards, both simple and slotted beam are considered. To understand the effect of slot positions and sizes on the resonator performance, resonant frequency and thermoelastic quality factor are calculated for both simple and slotted beams for a wide range of beam length from 10 to 400 µm. Punching slots in the resonator beam reduces the stiffness and mass of the beam which affect the resonant frequency. In addition thermomechanical coupling mechanisms of the resonator are affected by the slots which improve the thermoelastic quality factor. For most of the beam lengths, it is shown that the slots at the beam-anchor interface region, where the strain is high, are more effectively enhanced the thermoelastic quality factor than one at the centre of the beam region. However, the highest resonance frequency i...

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Effects of slots on thermoelastic quality factor of a vertical beam MEMS resonator

Asadi

Sheikholeslami

2015

Microsyst Technol

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“…As a replica, improved matching is achieved between the variable-gain amplifier and the bias circuitry. Furthermore, by allowing the bias voltage to dynamically change with process, voltage and temperature (PVT) variations, the amplifier chain is kept stable and the system becomes more robust against disturbances [40].…”

Section: Bias Replicamentioning

confidence: 99%

A variable-gain transimpedance amplifier for MEMS-based oscillators

Filho¹

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A variable gain Transimpedance Amplifier (TIA) is presented. Realized in 0.18 µm technology, this amplifier was conceived with the purpose of providing oscillation sustaining for Micro-Electro-Mechanical System (MEMS) based oscillators. Facing a quite challenging trade-off between Gain, Bandwidth, Noise and Power consumption, the TIA was implemented through the cascade of four similar gain stages, with the application of shunt-shunt feedback to lower both input and output resistances. With the employment of a variable-gain stage, this TIA presents a large gain tunability of 53 dB, with a also large maximum transimpedance gain of 118 dBΩ.The circuit simulation also points to a minimum Input-referred Noise Current of 2.51 pA/ √ Hz, and the Replica Biasing method confers a distinct robustness against severe PVT variations. The system also incorporates an Automatic Gain Control (AGC) circuitry to address a poor MEMS Power Handling Capability, and the addition of decoupling capacitors further augments the design applicability. Finally, the obtained transimpedance amplifier is suitable to provide oscillation sustaining for a wide variety of MEMS resonators, and the achievement of an improved noise performance paves the way for a resultant low Phase Noise oscillator.

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