High-Q factor circuit with reduced sensitivity

An active network is suggested that uses one differential-input operational amplifier and is suitable for realising high-Q factor second-order bandpass functions. Its Q sensitivity to component values is found to be less than the optimum Q sensitivities of the corresponding networks of Huelsman and Antoniou. The network has been used to realise a sixth-order bandpass filter in three cascaded stages. Experimental results are given.     

High-Q factor frequency-temperature compensated sapphire Bragg distributed resonator

A new sapphire TE/sub 10/spl delta// resonator was constructed with a novel support structure made from sapphire and rutile. The amount of rutile was chosen to act as Bragg reflectors to reduce conductor losses while simultaneously aning the temperature coefficient of frequency. The resonator was confirmed to have an annulment temperature of -8/spl deg/C and Q-factor of 65,000 limited by the dielectric loss tangent.     

Improvement of the quality factor of RF integrated inductors bylayout optimization

A systematic method to improve the quality (Q) factor of RF integrated inductors is presented in this paper. The proposed method is based on the layout optimization to minimize the series resistance of the inductor coil, taking into account both ohmic losses, due to conduction currents, and magnetically induced losses, due to eddy currents. The technique is particularly useful when applied to inductors in which the fabrication process includes integration substrate removal. However, it is also applicable to inductors on low-loss substrates. The method optimizes the width of the metal strip for each turn of the inductor coil, leading to a variable strip-width layout. The optimization procedure has been successfully applied to the design of square spiral inductors in a silicon-based multichip-module technology, complemented with silicon micromachining postprocessing. The obtained experimental results corroborate the validity of the proposed method. A Q factor of about 17 have been obtained for a 35-nH inductor at 1.5 GHz, with Q values higher than 40 predicted for a 20-nH inductor working at 3.5 GHz. The latter is up to a 60% better than the best results for a single strip-width inductor working at the same frequency     

High-Q GaAs varactor diodes

A double epitaxial gallium arsenide tuning diode has been developed for TV varactor tuners. The capacitance variation ratio is 6.0 and is large enough to cover the UHF TV broadcasting band. Diode series resistance is 0.18 Ω (Q = 200) at 470 MHz, and at a capacitance of 9 pF. This resistance is 4.4 times smaller than Si diodes in its mean value. Contribution of each resistance component to the total diode resistance was studied. The result shows that package loss is 0.11 Ω, RF skin-effect resistance is 0.05 Ω, and the undepleted epitaxial layer resistance is 0.048 Ω. Therefore, a diode with a 0.075-Ω (Q = 480) series resistance at 470 MHz could be developed, if package loss and RF skin-effect resistance are improved.     

High-Q HF microelectromechanical filters

IC-compatible microelectromechanical intermediate frequency filters using integrated resonators with Q's in the thousands to achieve filter Q's in the hundreds have been demonstrated using a polysilicon surface micromachining technology. These filters are composed of two clamped-clamped beam micromechanical resonators coupled by a soft flexural-mode mechanical spring. The center frequency of a given filter is determined by the resonance frequency of the constituent resonators, while the bandwidth is determined by the coupling spring dimensions and its location between the resonators. Quarter-wavelength coupling is required on this microscale to alleviate mass loading effects caused by similar resonator and coupler dimensions. Despite constraints arising from quarter-wavelength design, a range of percent bandwidths is still attainable by taking advantage of low-velocity spring attachment locations. A complete design procedure is presented in which electromechanical analogies are used to model the mechanical device via equivalent electrical circuits. Filter center frequencies around 8 MHz with Q's from 40 to 450 (i.e., percent bandwidths from 0.23 to 2.5%), associated insertion losses less than 2 dB, and spurious-free dynamic ranges around 78 dB are demonstrated using low-velocity designs with input and output termination resistances of the order of 12 kΩ     

Permalloy thin-film inductors

The design of an integrated thin-film inductor suitable for use at 10 MHz is described, and some operational characteristics are given. The inductor has the shape of a square spiral and is surrounded by permalloy thin films according to a certain pattern. This pattern allows these films to be driven in the hard direction and thus utilises the hard-direction permeability which is quite large (?2700).     

Self-capacitance of inductors

A new method for predicting the stray capacitance of inductors is presented. The method is based on an analytical approach and the physical structure of inductors. The inductor winding is partitioned into basic cells-many of which are identical. An expression for the equivalent capacitance of the basic cell is derived. Using this expression, the stray capacitance is found for both single- and multiple-layer coils, including the presence of the core. The method was tested with experimental measurements. The accuracy of the results is good. The derived expressions are useful for designing inductors and can be used for simulation purposes     

变压器和电感器

可承载40A的自屏蔽SMT电感器 HM73系列钼铁镍合金粉末自屏蔽SMT电感器从0.1～8.2μH有16种额定值,最高可承受40A和400μJ/cm~3。它们是用导体密度比圆形导线高20％的超薄矩形导线制造的,它们还具有0.08～15.2mΩ的DCR。     

GaN-Based High-Q Vertical-Cavity Light-Emitting Diodes

We report a fabrication and demonstration of a GaN-based high-Q vertical-cavity light-emitting diode (VCLED). The GaN VCLED is composed of a 25-pair high-reflectivity (98%) GaN/AlN distributed Bragg reflector (DBR), an eight-pair SiO₂/Ta₂O₅ dielectric DBR (99%), and a three-lambda optical thickness InGaN/GaN active region. It shows a very narrow linewidth of 0.52 nm, corresponding to a cavity Q -value of 895 at a driving current of 10 mA and a dominant emission peak wavelength at 465.3 nm. In addition, this VCLED emission linewidth continues to decrease with an increasing injection current, suggesting a possible realization of GaN-based vertical-cavity surface emitting lasers.     

On-chip solenoid inductors with high quality factor for high frequency magnetic integrated circuits

On-chip solenoid inductors for high frequency magnetic integrated circuits are proposed. The eddy current loss was reduced by dividing the inductor into three consecutive inductors connected in series. The inductor has an inductance of 1.1nH and the maximum quality factor (Q/sub max/) of 50.5. The self-resonant frequency and the operating frequency at Q/sub max/ are greater than 17.5GHz and 16.7GHz, respectively.     

Self-assembled screen-printed microwave inductors

The fabrication and measured performance of a self-assembled microwave inductor, created using a novel screen-printing technology, is reported for the first time. Real surface micromachining is performed using screen printing, by introducing a unique sacrificial layer. The self-assembled inductor demonstrated a significantly increased unloaded Q-factor and first self-resonant frequency.     

Design of microfabricated inductors

Possible configurations for microfabricated inductors are considered. Inductance can be set by adjusting permeability through control of anisotropy of a permalloy core or via a patterned quasi-distributed gap. A design methodology based on a simple model is proposed. A more accurate model and a numerical optimization are also developed. Design examples for 5- and 10-MHz buck converters and 2.5-MHz resonant converter applications are presented     

Digital inductors and capacitors

Circuits are described for simulating inductors and capacitors by digital (hardware) techniques. Filter and oscillator applications are discussed and test results are given.     

SMPS功率电感器的选择

开关模式电源(SMPS)功率电感器的选择过程绝非是信手拈来那么简单,必须要对对实际电感器有充分的了解。SMPS的选用要求包括:大功率、小尺寸、高开关频率和高效率。此外,考虑到健康、环保方面的因素,很多用户还提出了降低电磁辐射(EMI)的要求。理想的电感器选择除了取决于对实际电感器(并不完善的)特性的了解之外,还需要对完善的电感器特性有一定的通晓。储能方面的考虑14种基本的SMPS设计大多依靠电感器来进行储能和EMI抑制(滤波)。控制电路负责对储存的能量进行调节,并通过将电感器与电源相连的方法来增加能量的存储。存储在一个电…     

Broad-Band Coupling of High-Q Resonant Loads

Considering the method of broad-band coupling a series resonant RLC load to a resistive source using a uniform quarter-wave transmission-line inverter, it is shown that the 3-dB bandwidth of the network insertion loss reckoned with respect to a 0-dB loss attains a maximum for a particular value of the center frequency insertion loss in the range 0-3 dB. The center frequency Ioss and the corresponding value of the maximum 3-dB bandwidth are calculated for various loads and the results graphically presented.     

Broad-Band Coupling to High-Q Resonant Loads

Broad-band coupling between a resistive source and a resonant load is considered for coupling networks consisting of a uniform transmission line of impedance Z/sub I/ and length equal to a quarter wavelength at the load resonant frequency. An approximate analysis is used to show that either maximally flat or ripple insertion loss frequency response can be obtained by proper choice of Z/sub I/, and the 3-dB bandwidth obtained in either case is always greater than 1/Q. Depending on the ratio of load and source resistances, the bandwidth may be greater than 1 octave. Network design curves for maximally flat operation with a variety of load parameters are computed without approximation. The design of lumped element approximations for the transmission line network is also described.     

High-Q microwave acoustic resonators and filters

The authors present recent experimental and modeling results for high-Q microwave acoustic resonators and filters for use in oscillators and other frequency control applications. Overmoded resonators have exhibited an FQ product greater than 1×10¹⁴ Hz (e.g., Q=68,000 at 1.6 GHz) with a strong inductive response suitable for one-port and two-port oscillator feedback circuits. Ladder filters fabricated with overmoded resonators have loaded Qs greater than 40,000 with 76-kHz bandwidth at 1.6 GHz. Aluminum nitride films were used for transduction on Z-cut sapphire and lithium niobate substrates     

High-Q vertically coupled InP microdisk resonators

High-quality factor vertically coupled InP microdisk resonators have been fabricated. Wafer bonding techniques have been used as a main approach to enable this three-dimensional structure. The devices exhibit smooth sidewalls, single mode operation, and high-quality factors in excess of 7000