Analytical wide-band modeling of high frequency resistance in integrated spiral inductors

For integrated spiral inductor synthesis, designers and design automation tools require efficient modeling techniques during the initial design space exploration process. In this paper, we introduce an analytical frequency-dependent resistance model for integrated spiral inductors. Based on our resistance formulation, we have developed a systematic technique for creating wide-band circuit models for accurate time domain simulation. The analytical resistance model provides a fast alternative to field solver-based approaches with typical errors of less than 2.6 percent while surpassing the accuracy of several other analytical modeling techniques by an order of magnitude. Furthermore, the wide-band circuit generation technique captures the frequency-dependent resistance of the inductor with typical errors of less than 3.2 percent.     

Parasitic-aware analytical modeling of integrated CMOS inductively degenerated narrow-band low noise amplifiers

In this paper, we present an analytical modeling methodology for fully integrated inductively-degenerated CMOS narrow-band cascode Low Noise Amplifiers (LNA) that captures short channel transistor effects to enable rapid design space exploration in current and future process technologies. The modeling methodology captures the impact of parasitics on passive components, ESD-protection structures, and devices to accurately predict both impedance matching and noise figure. Our modeling is suitable for numerical optimization and fully automated synthesis for LNAs. The results indicate that the methodology models ESD-protected LNA circuits with 47.9% better accuracy in noise figure when compared with several current analytical modeling techniques with four orders of magnitude improvement in simulation time over circuit-level simulation. Given its speed and accuracy, the analytical modeling methodology is well-suited for design space exploration.     

Design techniques for reducing the impact of component variations on narrow-band low noise amplifiers

Given the increasing demand for integrated wireless systems in system-on-chip technology, narrow-band low noise amplifier (LNA) designs must be robust against variations in device parameters and passive component values to improve manufacturing yield for high volume applications. In this paper, we develop two design techniques for reducing the impact of component variations on narrow-band LNA performance. The results demonstrate that by increasing the bandwidth of the narrow-band LNA and applying more conservative design constraints, we can mitigate the reliability implications of process variations on impedance matching, gain, and power consumption.     

Analysis of the composition of the passive film on iron under pitting conditions in 0.05 M NaOH/NaCl using Raman microscopy in situ with anodic polarisation and MCR‐ALS

The composition of the surface film formed on pure iron was investigated in a solution of 0.05 M NaOH and 0.05 M NaCl. Raman spectra of the film were recorded in situ during anodic polarisation over the passive region after addition of the NaCl to the electrolyte, under conditions of preresonance enhancement using excitation at 636.4 nm. Multivariate curve resolution with alternating least squares analysis was applied to the spectra to measure the relative amounts of different iron oxide and oxyhydroxides in the film at different potentials. The water content was also determined in this way from Raman spectra recorded using excitation at 514.5 nm. It was found that the composition of the film and the amount of incorporated water were influenced by the applied anodic potential. The results show that stable pitting can occur when the composition changes from the primary constituents β‐FeOOH and Green Complex (a hydrated, amorphous magnetite) with smaller amounts of γ‐Fe₂O₃ and γ‐FeOOH, to δ‐FeOOH and Green Complex, simultaneously with a reduction in water content. These changes result in conditions that favour the rate of localised breakdown of the film by Cl⁻ ions over the rate of repassivation by water in the passive film. Copyright © 2011 John Wiley & Sons, Ltd.     

Short range order at the amorphous TiO(2)-water interface probed by silicic acid adsorption and interfacial oligomerization: an ATR-IR and 29Si MAS-NMR study

Adsorption and oligomerization of H(4)SiO(4) at the amorphous TiO(2)-aqueous interface were studied using in situ Attenuated Total Reflectance Infrared (ATR-IR) and ex situ solid state (29)Si nuclear magnetic resonance (NMR). The ATR-IR spectra indicate that a monomeric silicate species is present at low silicate surface concentration (Γ(Si)). Above a threshold Γ(Si) linear silicate oligomers are formed and these oligomers dominate the surface at high Γ(Si). Interestingly the ATR-IR spectra of H(4)SiO(4) on the TiO(2) surface are very similar to those previously observed on the poorly ordered iron oxide phase ferrihydrite. The (29)Si NMR spectrum of silicate on the TiO(2) surface shows the presence of Si in three states with chemical shifts corresponding to isolated monomers (Q(0)), the ends of linear oligomers (Q(1)) and the middle of linear oligomers (Q(2)). The ratio of the area of the Q(1) and Q(2) peaks was ≈2:1 which is consistent with the proposed formation of linear silicate trimers by insertion of a solution H(4)SiO(4) between adjacent suitably orientated adsorbed silicate monomers. A structural interpretation indicates that the observed interfacial silicate oligomerization behavior is a general phenomenon whereby bidentate silicate monomers on oxide surfaces are disposed towards forming linear oligomers by condensation reactions involving their two terminal Si-OH groups. The high surface curvature of nanometer sized spheres inhibits the formation of interfacial silicates with a higher degree of polymerization.     

Determination of patulin in apple juice by high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry

An HPLC-MS-MS method with selected reaction monitoring (SRM) for the determination of patulin in apple juice samples is described. Mass spectrometric detection was accomplished following atmospheric pressure chemical ionization (APCI) in both positive and negative ion modes. Collision induced dissociation (CID) of the protonated molecular ion led initially to the loss of H2O (fragment m/z 137). At higher energies CO is lost from both the protonated parent molecule (fragment m/z 127) and the dehydrated molecular ion (fragment m/z 109). In contrast, CID of the deprotonated molecular ion led initially to the fragment at m/z 109 corresponding to the loss of either CO2 or acetaldehyde, followed at higher CID energy by the loss of H2O (fragment m/z 135) and CO (fragment m/z 125) from the deprotonated molecular ion. Detection in the negative ion mode proved superior and a linear response was observed over the injected range from 6 to 200 ng patulin. Apple juice samples spiked with patulin between 10 and 135 microg/l were analyzed following liquid-liquid extraction with ethyl acetate and clean up with sodium carbonate. Utilizing reversed-phase HPLC with acetonitrile-water (10:90) at 0.5 ml/min, levels down to 10 microg/l were readily quantified and a detection limit of 4 microg/l was attainable at a signal-to-noise (SIN) ratio of 4. The MS data for the spiked samples compared well to the UV data and when plotted against each other displayed a correlation coefficient (R) of 0.99.     

Design optimization of switchable multi-port spiral inductors

In this paper, we develop a design optimization methodology for switchable multi-port spiral inductors in fully integrated wireless systems. The methodology simultaneously maximizes the inductor’s performance for multiple inductance values and operating frequencies. We utilize multi-level optimization techniques to efficiently design the geometry of the switchable inductor structure. The methodology can produce designs with significantly larger quality factors than those obtained by optimizing the inductor design for a single inductance value and operating frequency.     

Narrow-band low-noise amplifier synthesis for high-performance system-on-chip design

In this paper, we present a systematic synthesis methodology for fully integrated narrow-band CMOS low-noise amplifiers (LNAs) in high-performance system-on-chip (SoC) designs. The methodology is based on deterministic gradient-based numerical nonlinear optimization and the normal boundary intersection (NBI) method for Pareto optimization. We simultaneously optimize transistor widths, bias voltages, and input and output matching network passive components, which yields integrated inductor values that are more than one order of magnitude less than those generated by several existing equation-based LNA design techniques. By generating significantly smaller inductor values, we enable the SoC integration of the complete LNA. When the synthesized LNAs are characterized using circuit-level simulation, our methodology yields up to 35% and 58% improvement in noise figure and gain, respectively.     

Transport and percolation in disordered systems—A self-consistent time-local approach

A new self-consistent equation for the transport of excitations in disordered systems, which forms the basis for a new class of time-domain coherent potential approximations, is developed. As an example, we calculate the probability of remaining in the original site G₀(t) as well as the second moment of the distribution of excitations r²(t) for a random mixture of donors which satisfy a master equation with short-range transition rates. A percolation-type transition is observed and its characteristics are analyzed both above and below the transition point.Alfred P. Sloan fellow, Camille and Henry Dreyfus teacher-scholar.