Maximum Resonance Frequency Research Articles

Noise-Cancelling CMOS Active Inductor and Its Application in RF Band-Pass Filter Design

A CMOS active inductor with thermal noise cancelling is proposed. The noise of the transistor in the feed-forward stage of the proposed architecture is cancelled by using a feedback stage with a degeneration resistor to reduce the noise contribution to the input. Simulation results using 90 nm CMOS process show that noise reduction by 80% has been achieved. The maximum resonant frequency and the quality factor obtained are 3.8 GHz and 405, respectively. An RF band-pass filter has been designed based on the proposed noise cancelling active inductor. Tuned at 3.46 GHz, the filter features total power consumption of 1.4 mW, low noise figure of 5 dB, and IIP3 of −10.29 dBm.

Nuclear Magnetic Resonance Imaging in Patients With Cardiac Pacing Devices

Currently, nuclear magnetic resonance imaging is contraindicated in patients with a pacemaker or implantable cardioverter-defibrillator. This study was carried out because the potential risks in this situation need to be clearly defined. This prospective study evaluated clinical and electrical parameters before and after magnetic resonance imaging was performed in 33 patients (five with implantable cardioverter-defibrillators and 28 with pacemakers). In these patients, magnetic resonance imaging was considered clinically essential. There were no clinical complications. There was a temporary communication failure in two cases, sensing errors during imaging in two cases, and a safety signal was generated in one pacemaker at the maximum magnetic resonance frequency and output level. There were no technical restrictions on imaging nor were there any permanent changes in the performance of the cardiac pacing device.

Development of 3D Force Sensors for Nanopositioning and Nanomeasuring Machine

In this contribution, we report on different miniaturized bulk micro machined three-axes piezoresistive force sensors for nanopositioning and nanomeasuring machine (NPMM). Various boss membrane structures, such as one boss full/cross, five boss full/cross and swastika membranes, were used as a basic structure for the force sensors. All designs have 16 p-type diffused piezoresistors on the surface of the membrane. Sensitivities in x, y and z directions are measured. Simulated and measured stiffness ratio in horizontal to vertical direction is measured for each design. Effect of the length of the stylus on H:V stiffness ratio is studied. Minimum and maximum deflection and resonance frequency are measured for all designs. The sensors were placed in a nanopositioning and nanomeasuring machine and one point measurements were performed for all the designs. Lastly the application of the sensor is shown, where dimension of a cube is measured using the sensor.

Novel Microstrip Antenna With Rotatable Patch Fed by Coaxial Line for Personal Handy-Phone System Units

An enhanced microstrip antenna is proposed that incorporates a patch that rotates around the inner conductor of the coaxial line or dielectric shaft and a novel coaxial line feeding technique that offers constant electromagnetic coupling. This proposal addresses the disadvantages in our previous patch antenna in which the resonant frequency diverges from the center frequency of the personal handy-phone system (PHS) band and the bandwidth decreases as the patch rotates because of the changing electromagnetic coupling between the patch and microstrip line due to the patch rotation. We verify that this enhanced patch antenna achieves the antenna gain of approximately 0 dBd, which is the same as that of the previously proposed antenna, while suffering no significant gain degradation due to unit inclination over inclination angles from plusmn45deg compared to a conventional quarter-wavelength whip antenna, which experiences a degradation of approximately 2.7 dB. We show that the maximum resonant frequency separation from the center frequency of the PHS band is reduced to 15 MHz from 31.4 MHz of the previous antenna using the novel coaxial line feeding technique. The effective bandwidth needed for PHS is achieved over the inclination angles of -20deg to +40deg. Approximately 93% of the total bandwidth needed for PHS is achieved while the previous microstrip line type achieved only 58% coverage; accordingly, an adequate bandwidth for PHS use is obtained.

CMOS source degenerated differential active inductor

A new CMOS source degenerated differential active inductor is proposed. The proposed differential active inductor required only six transistors or more for proper operation. It is very compact compared to a conventional differential active inductor that was design using two differential transconductors and which requires at least ten transistors. The proposed active inductor was fabricated using Silterra 0.18 µm CMOS process for demonstration. Measurement results show that the proposed active inductor has a wide tuning range with a maximum resonance frequency of 7.85 GHz.

Scaling of resonance frequency for strong injection-locked lasers

It has been shown that strong optical injection locking can significantly enhance the resonance frequency of semiconductor lasers. In this Letter, we describe the trade-off between the maximum resonance frequency enhancement and the quality factor (Q) of the lossless laser cavity and show that the time-bandwidth product (product of photon lifetime and maximum resonance frequency) is equal to one half the square root of the external power injection ratio. The theoretical model agrees well with our experimental data.

Optimization of optical modulator chirp measurement technique using differential frequency beating

AbstractOptimization of the optical modulator chirp measurement technique using differential frequency beating is presented in this paper. The performance of the chirp measurement technique is studied in terms of the measurement range, sensitivity, and resonant frequency as the accumulated chromatic dispersion (CD) in the fiber is varied. Based on the mathematical model and experimental and simulation results, the technique's measurement range and sensitivity increase with reduced accumulated CD in the fiber. However, the resonant frequencies increase with reduced accumulated CD. The chirp measurement technique is optimized at an accumulated CD of ∼600 ps/nm, with a measurement range of ±4.75, maximum sensitivity of 3.3 GHz, and maximum resonant frequency of 14.28 GHz. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2306–2309, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22718

Assessment of correlation between computerized tomography values of the bone, and maximum torque and resonance frequency values at dental implant placement

The aim of this study was to determine the bone density in the designated implant sites using computerized tomography (CT), the fastening torque values of dental implants, and the implant stability values using resonance frequency analysis. Further aim was to evaluate a possible correlation between bone density, fastening torque and implant stability. Eighty-five patients were treated with 158 Brånemark System implants. CT machine was used for preoperative evaluation of the jawbone for each patient, and bone densities were recorded in Hounsfield units (HU). The fastening torque values of all implants were recorded with the OsseoCare equipment. Implant stability measurements were performed with the Osstell machine. The average bone density and fastening torque values were 751.4 +/- 256 HU and 39.7 +/- 7 Ncm for 158 implants. The average primary implant stability was 73.2 +/- 6 ISQ for seventy implants. Strong correlations were observed between the bone density, fastening torque and implant stability values of Brånemark System TiUnite MKIII implants at implant placement (P < 0.001). These results strengthen the hypothesis that it may be possible to predict and quantify initial implant stability and bone quality from pre-surgical CT diagnosis.

Effects of different sintering temperature and Nb 2O 5 content on structural and magnetic properties of Z-type hexaferrites

Nb-doped Z-type hexaferrites (Ba 3(Co 0.4Zn 0.6) 2Fe 24O 41) with composition of Ba 3(Co 0.4Zn 0.6) 2Fe 24O 41+ x Nb 2O 5 (where x=0.0, 0.1, 0.2, 0.4, 0.6, 0.8, 1.2, 1.6 and 2.0 wt%) were prepared by a solid-state reaction method. The effects of different sintering temperature ( T s) and Nb 2O 5 content on the sintering behaviors, phase composing, microstructure, and magnetic properties of the samples were investigated. The results from X-ray diffraction and scanning electron microscopy show that as the amount of Nb 2O 5 additive increases, the major phase changes to Z-phase, Simultaneously, M-phase and a small amount of niobate phase appear. The Nb 2O 5 additive promotes the grain growth as reaction center at lower sintering temperature (1220 °C), but at higher temperature (1260 °C), niobate phase separated out in grain boundaries as secondary phase will restrain abnormal grain growth, so closed pores in grains are not formed. The Nb 2O 5 additive can enhance densification, improve initial permeability of hexaferrites by increasing the grain growth of hexaferrite and the displacement of ions in the sintering process due to the aberration and activation of crystal lattice, which is accompanied by the solubility of Nb 5+ in the hexaferrites. A relative density of 96%, maximum initial permeability (32–33), minimum coercivity (454–455 A/m) and resonance frequency above 400 MHz were obtained for the sample with 0.8 wt% Nb 2O 5 sintered at 1260 °C for 6 h.

Analog Modulation of 650-nm VCSELs

Small-signal properties of 650-nm vertical-cavity surface-emitting lasers (VCSELs) with different oxide aperture sizes were measured. A small diameter VCSEL of 3.5 mum has a maximum resonance frequency of 5.7 GHz. The photon density determines the maximum resonance frequency. Modeling also indicates higher photon densities in the small VCSEL due to better thermal behavior

Nonlinear dynamics of a directly modulated semiconductor laser with cavity detuning

A detailed numerical study of dynamical behavior of a semiconductor laser under current modulation and cavity detuning has been performed on the base of four different models of the active medium which take into account direct transitions between ground subbands, transitions with no k-selection rule between ground subbands and contribution of excited subbands in each of the above-mentioned cases. We have shown that different nonlinear regimes (period doubling, chaos, generalized bistability) can be obtained either with cavity detuning from the gain band maximum or near the laser threshold.It has been established that the shape and principal peculiarities of amplitude detuning characteristics are determined by the relation between the current modulation frequency and maximum resonance frequency of the laser.

A spectral vibration detection system based on tunable micromechanical resonators

We present a frequency selective vibration detection system based on tunable micromechanical resonators for the frequency range 1–10 kHz. The Single Crystal Reactive Etching and Metallization (SCREAM)-fabricated sensor structure consists of an array of eight resonators with stepped base frequencies between 2.8 and 10.2 kHz. The resonators provide a resonance frequency tuning capability by electrostatic forces to set the detection frequency to the desired value. Experimental results of the fabricated resonator arrays are presented. A maximum tuning voltage of 35 V is required for continuous resonance frequency tuning from 1 to 10 kHz. The amplitude range of the resonators amounts to 10 μm. Over the whole amplitude range, a maximum resonance frequency shift of 0.7% was measured. An increase of ambient temperature from 30 to 150 °C results in a small resonance shift of 0.5% and to an increase of resonance peak bandwidth of 23%. The sensor structure is part of a vibration detection system, which is completed with analogue and digital circuitry. Test measurements with the system demonstrate its functionality and applicability in an industrial environment.

SOI 웨이퍼를 이용한 압전박막공진기 제작

Film Bulk Acoustic Resonator (FBAR) using thin piezoelectric films can be made as monolithic integrated devices with compatibility to semiconductor process, leading to small size, low cost and high Q RF circuit elements with wide applications in communications area. This paper presents an MMIC compatible suspended FBAR using SOI micromachining. It is possible to make a single crystal silicon membrane using a SOI wafer In fabricating active devices, SOI wafer offers advantage which removes the substrate loss. FBAR was made on the 12㎛ silicon membrane. Electrode and Piezoelectric materials were deposited by RF magnetron sputter. The maximum resonance frequency of FBAR was shown at 2.5GHz range. The reflection loss, K<TEX>$^2$</TEX><TEX>$\_$</TEX>eff/, Q<TEX>$\_$</TEX>serise/ and Q<TEX>$\_$</TEX>parallel/ in that frequency were 1.5dB, 2.29%, 220 and 160, respectively.

Relative intensity noise measurements of a widely tunable sampled-grating DBR laser

The intensity noise of a sampled-grating distributed Bragg reflector laser with 50-nm tuning range and 45-dB side-mode suppression ratio has been measured. The resonance frequency, damping factor, and modified Schawlow-Townes linewidth are extracted from the noise spectra. At high output power, the relative intensity noise (RIN) of the laser is below the photodiode shot noise limit, which is -160 dB/Hz. The laser has uniform shot noise limited RIN properties along the whole tuning range. The maximum resonance frequency is 5.4 GHz at a bias current of 120 mA and the K factor is 0.58 ns.

Megahertz silicon atomic force microscopy (AFM) cantilever and high-speed readout in AFM-based recording

Small atomic force microscopy (AFM) cantilever with a maximum resonant frequency of about 6.6 MHz was developed using a Si microprocess with silicon-on-insulator wafer. The cantilever was triangular in shape with a length of 7–20 μm and a thickness of &amp;lt;0.3 μm and had a tip on the lever. These structures were precisely fabricated by buffer step and prestep and using dual-side aligner. Furthermore, we developed a new optical lever deflection detection system for the small cantilever with a magnifying power of 0.2 μm/Å and a spot size of 2 μm. We demonstrate a high resonant frequency of the cantilever and a high speed readout at higher than 5 Mb/s using the prototype of rotation AFM recording system with a new detection system.

Modulation of frequency selectivity by Na +- and K +-conductances in neurons of auditory thalamus

In thalamic neurons, frequency-filter properties arise from intrinsic membrane properties which transform sensory inputs to thalamocortical signals. They also contribute to the tendency for the membrane to generate synchronized oscillations. We studied the frequency selectivities of thalamocortical neurons in the rat ventral medial geniculate body (MGBv) in vitro, using whole-cell recording techniques, sinewave (swept `ZAP' or single) current inputs and pharmacological blockade of membrane currents. In a voltage range that was subthreshold to spike genesis, the frequency responses below 20 Hz were voltage-dependent; they exhibited lowpass characteristics at depolarized potentials and bandpass resonance (near 1 Hz) in the activation range (∼−65 to −50 mV) of the low-threshold Ca 2+-current ( I T). A temperature increase of >10°C in 3 neurons did not change this voltage-dependence and increased the frequency of maximum resonance to 2 Hz. The removal of extracellular Ca 2+, its equimolar substitution with Mg 2+ or blockade of I T with Ni 2+ (0.5 mM) completely blocked the resonance at hyperpolarized potentials or rest, as well as the low-threshold Ca 2+-spike (LTS). Blockade of high threshold Ca 2+-currents with Cd 2+ (50 μM) did not affect the resonance. These data implied that, like the LTS, an activation of I T produced the membrane resonance. An increased ZAP-current input evoked action potentials near the resonant frequency as well as Cd 2+-sensitive high-threshold Ca 2+-spikes at depolarized membrane potentials and very low frequencies. By blocking a persistent Na +-current ( I NaP), tetrodotoxin (300 nM) reduced the magnitude of the frequency response without affecting the frequency preference. The response was larger in amplitude, especially at frequencies lower than the maximum resonant frequency, when we used 4-aminopyridine (0.05–0.1 and 1–2 mM), Ba 2+ (0.2 mM) or Cs + (3 mM) to block voltage-dependent K +-currents. From these data, we suggest that A-type ( I A and I As) and inwardly rectifying ( I KIR) K +-currents modulate resonance, changing the quality of the lowpass filter function. We conclude that the generation of membrane resonance in MGBv neurons depends critically on I T-activation while the quality of the frequency response is subject to modulation by voltage-dependent conductances. The frequency selectivities in MGBv may contribute to lowpass filter functions for auditory transmission during wakefulness and oscillations observed during sleep.

High-temperature, low threshold current, and uniform operation 1×12 monolithic AlGaInAs/InP strain-compensated multiple quantum well laser array in 1.5 μm

In this paper, we describe the fabrication of a monolithically integrated 1/spl times/12 array of 1.5-/spl mu/m AlGaInAs/InP strain-compensated multiple-quantum-well (MQW) lasers, which has high reliability and highly uniform characteristics in low threshold current, slope efficiency, and lasing wavelength. Besides, each diode on the array exhibits a high characteristic temperature of 88 K and a low slope-efficiency drop of less than 1 dB between 20-80/spl deg/C and a lasing wavelength of 1510 nm at 20/spl deg/C and 20 mA. Also, the diode on the array has a maximum resonance frequency of above 8 GHz or 3-dB modulation bandwidth of 12 GHz.

Two-axis electrodynamic micropositioning devices

Highly dynamic positioning devices for small elements are an interesting field for microactuators. Fields of very promising application are microoptics and microbiology. Applications in microoptics are the biaxial positioning of microoptical chips, microlenses and prisms for beam shaping and deflection and in microbiology the movement of microtools for the manipulation of biological cells and microorganisms. For these applications two highly dynamic positioning devices are being developed which are capable of handling tight mechanical tolerances. The rotors of the integrated multi-axis drives with two degrees of freedom have a maximum motion range of 300 m. The maximum resonance frequency is over 1000 Hz. The actuators use the electrodynamic motion principle. The technologies of wet chemical etching of silicon and galvanic batch processes are used. Furthermore this paper describes a method which can be used to predict the dynamic and static characteristics of electrodynamic actuators with a few input parameters.

Relative intensity noise and linewidth measurements of a widely tunable GCSR laser

The intensity and frequency noise of a grating assisted codirectional coupler with rear sampled grating reflector laser with 40-nm tuning range and 35-dB sidemode suppression ratio (SMSR) have been measured. The linewidth varies from 430 kHz to 4 MHz as a function of tuning. The resonance frequency, intrinsic bandwidth and damping factor for this device were extracted from the relative intensity noise (RIN) measurements. At high bias, the RIN is -150 dB/Hz and the maximum resonance frequency is 4.5 GHz.

Turbulence, waves and mixing at shear-free density interfaces. Part 1. A theoretical model

This paper presents a theoretical model of turbulence and mixing at a shear-free stable density interface. In one case (single-sided stirring) the interface separates a layer of fluid of density ρ in turbulent motion, with r.m.s. velocity uH and lengthscale LH, from a non-turbulent layer with density ρ+Δρ, while in the second case (double-sided stirring) the lower layer is also in turbulent motion. In both cases, the external Richardson number Ri=ΔbLH/ u2H (where Δb is the buoyancy jump across the interface) is assumed to be large. Based on the hypotheses that the effect of the interface on the turbulence is as if it were suddenly imposed (which is equivalent to generating irrotational motions) and that linear waves are generated in the interface, the techniques of rapid distortion theory are used to analyse the linear aspects of the distortion of turbulence and of the interfacial motions. New physical concepts are introduced to account for the nonlinear aspects.To describe the spectra and variations of the r.m.s. fluctuations of velocity and displacements, a statistically steady linear model is used for frequencies above a critical frequency ωr/μc, where ωr(=Δb/2uH) is the maximum resonant frequency and μc&lt;1. As in other nonlinear systems, observations below this critical frequency show the existence of long waves on the interface that can grow, break and cause mixing between the two fluid layers. A nonlinear model is constructed based on the fact that these breaking waves have steep slopes (which determines the form of the displacement spectrum) and on the physical argument that the energy of the vertical motions of these dissipative nonlinear waves should be comparable to that of the forced linear waves, which leads to an approximately constant value for the parameter μc. The model predictions of the vertical r.m.s. interfacial velocity, the interfacial wave amplitude and the velocity spectra agree closely with new and published experimental results.An exact unsteady inviscid linear analysis is used to derive the growth rate of the full spectrum, which asymptotically leads to the growth of resonant waves and to the energy transfer from the turbulent region to the wave motion of the stratified layer. Mean energy flux into the stratified layer, averaged over a typical wave cycle, is used to estimate the boundary entrainment velocity for the single-sided stirring case and the flux entrainment velocity for the double-sided stirring case, by making the assumption that the ratio of buoyancy flux to dissipation rate in forced stratified layers is constant with Ri and has the same value as in other stratified turbulent flows. The calculations are in good agreement with laboratory measurements conducted in mixing boxes and in wind tunnels. The contribution of Kelvin–Helmholtz instabilities induced by the velocity of turbulent eddies parallel to the interface is estimated to be insignificant compared to that of internal waves excited by turbulence.