Efficient parasitic substrate modeling for monolithic mixed-A/D circuit design and verification

Parasitic analog-digital noise coupling has been identified as a key issue facing designers of mixed-signal integrated circuits. In particular, signal crosstalk through the common chip substrate has become increasingly problematic. This paper demonstrates a methodology for developing simulation, synthesis, and verification models to analyze the global electrical behavior of the non-ideal semiconductor substrate. First, a triangular discretization method is employed to generate RC equivalent-circuit substrate models which are far less complex than those formulated by conventional techniques. The networks are then accurately approximated for subsequent analysis by an efficient reduction algorithm which uses a well-conditioned Lanczos moment-matching process. Through congruence transformations, the network admittance matrices are transformed to reduced equivalents which are easily post-processed to derive passive, SPICE-compatible netlist representations of the reduced models. The pure-RC properties of the extracted substrate networks are fully exploited to formulate an efficient overall algorithm. For validation, the strategy has been successfully applied to several mixed-signal circuit examples.     

Performance of GaAs power m.e.s.f.e.t.s

Power performance results at 4 GHz are summarised for GaAs m.e.s.f.e.t.s ranging in size from 4 to 16 mm gate periphery. A double-chip 16 mm unit operated at 24 V source-drain bias produced 13.5 W with 3 dB gain and 10.7 W with 8.1 dB gain. Although lack of perfect power and gain scaling is observed, the degradation in output power of the 16 mm devices was only 1 dB compared to the smaller devices.     

Materials for magneto-optic modulators

A review of the current status of magneto-optic modulator materials is presented with emphasis on operation at the Nd³⁺:YAG wavelength of 1.064 μm. Because the iron garnets are “cubic”, exhibit small values of linear magnetic birefringence, and offer great flexibility in ion substitutions and some flexibility in optical absorption values, these materials provide clear advantages over any other known class of magnetic compounds. Recent work has also shown that Faraday rotati ons in the iron garnets can be remarkably enhanced by Bi³⁺ and/or Pr³⁺ substitutions. The physical origin of this enhancement is briefly outlined in terms of the iron garnet energy level structure. An important problem that has not as yet been completely resolved is the question of intrinsic optical absorption at 1.064 μm. Evidence is presented showing that optical losses in the 1–4 cm⁻¹ (0.43–1.7 db/mm) range should be achievable in praseodymium-substituted gadolinium iron garnet, but thus far the lowest observed absorption coefficient is 5.9 cm⁻¹ = 2.6 db/mm. In the case of bismuth-substituted garnets the lowest observed absorption at 1.064 μm is 13 cm⁻¹ = 5.6 db/mm. The importance of impurities, nonstoichiometry, and Pb incorporation from the flux is emphasized. Finally, we point out that other material properties such as magnetocrystalline anisotropy, ferromagnetic resonance frequency and linewidth, and values of 4πM_S should be included in any complete materials evaluation.     

Relationship between power added efficiency and gate-drain avalanche in GaAs m.e.s.f.e.t.s

Pulse avalanche measurements in the transistor three-terminal configuration reveal a correlation between pulse gate-drain avalanche and power added efficiency. This result, in conjunction with earlier work, points to simple design principles that can be used to maximise efficiency.     

Material dispersion slope in optical-fibre waveguides

The slope of the material dispersion dM/d? at ?0, the material dispersion zero where d2n/d?2=0, can be calculated to yield values applicable to crystals and glasses. The results, in units of ps/nm km ?m, range from 217 for B2O3 and 105 for SiO2 to 9 for TI2O and 0.40 for TlI. The key parameters affecting the material dispersion slope at ?0 are the chemical valence of the anion, the reduced mass and the density.     

MINERVA: a multi-modality plugin-based radiation therapy treatment planning system

Researchers at the INEEL, MSU, LLNL and UCD have undertaken development of MINERVA, a patient-centric, multi-modal, radiation treatment planning system, which can be used for planning and analysing several radiotherapy modalities, either singly or combined, using common treatment planning tools. It employs an integrated, lightweight plugin architecture to accommodate multi-modal treatment planning using standard interface components. The design also facilitates the future integration of improved planning technologies. The code is being developed with the Java programming language for interoperability. The MINERVA design includes the image processing, model definition and data analysis modules with a central module to coordinate communication and data transfer. Dose calculation is performed by source and transport plugin modules, which communicate either directly through the database or through MINERVA's openly published, extensible markup language (XML)-based application programmer's interface (API). All internal data are managed by a database management system and can be exported to other applications or new installations through the API data formats. A full computation path has been established for molecular-targeted radiotherapy treatment planning, with additional treatment modalities presently under development.     

Multichannel responses to an interpersonal stressor: Interrelationships among facial display, heart rate, self-report of emotion, and threat appraisal.

60 undergraduates were exposed to a potent, provocative interpersonal stressor while facial displays of emotion were unobtrusively videotaped and heart rate was continuously monitored. Following the stressor situation, Ss completed the Differential Emotions Scale and a questionnaire designed to assess S's appraisal of threat. The video-taped facial expressions were coded by 13 naive judges to assess the intensity of the expression displayed. Minimally expressive Ss reported experiencing more guilt, displayed a significant heart rate increase, and evaluated the situation as more threatening than did the expressive Ss. Results are consistent with aspects of a discharge model of emotion that predict an inverse relationship between overt emotional displays and physiological reactivity in response to an emotional stressor. Findings argue against a facial-feedback hypothesis. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)