A radix-8 wafer scale FFT processor

Wafer Scale Integration promises radical improvements in the performance of digital signal processing systems. This paper describes the design of a radix-8 systolic (pipeline) fast Fourier transform processor for implementation with wafer scale integration. By the use of the radix-8 FFT butterfly wafer that is currently under development, continuous data rates of 160 MSPS are anticipated for FFTs of up to 4096 points with 16-bit fixed point data.     

18-42 GHz experimental verification of microstrip coupler and openend capacitance models

A cavity resonance technique is used to experimentally verify microstrip coupler and open end capacitance models over the frequency range of 18-42 GHz. In addition, these results are confirmed using an alternate version of the technique which directly determines open end discontinuity capacitance. In the second case, knowledge of substrate dielectric constant is not required, and the method also yields the microstrip relative effective dielectric constant     

Investigation of high In content InGaAs quantum wells grown on GaAs by molecular beam epitaxy

Excitonic resonances and the quantum confined Stark effect are observed near 1.3 mu m in InGaAs quantum wells grown on GaAs using a slowly graded InGaAs buffer. The pin structure performs as a modulator with a relative transmission modulation of 12% at 1.3 mu m and as a low leakage photodetector.<>     

A simple model for quantum mechanical effects in hole inversionlayers in silicon PMOS devices

The effects of quantization of the inversion layer of MOSFET devices is an area of increasing importance as technology is aggressively scaled below 0.25 μm. Although electron inversion layers have attracted considerable interest, very little work has been reported for holes. This paper describes the implementation and results of a simple, computationally efficient model, appropriate for device simulators, for predicting the effects of hole inversion layer quantization. This model compares very favorably with experimental results and the predictions of a full-band, self-consistent Schrodinger-Poisson solver     

Design strategies and decoupling techniques for reducing theeffects of electrical interference in mixed-mode IC's

A key issue in the successful integration of analog circuits is a stable analog power supply. Traditional on-chip decoupling methods exhibit transients in the supply or voltage drops and power losses. This paper introduces the RLC decoupling method that features an enhanced transient response while being especially suited for low-power, low voltage applications. Both a theoretical and a practical approach are presented together with measurement results. As the benefits of a stable local power supply can be lost by the inadequate connection of two subcircuits with relative variations on the local grounds, a differential approach of signal transfer is proposed. Furthermore, the effect of a good local decoupling can be deteriorated by substrate noise, so some attention is given to this problem too     

System requirements for Ka-band Earth-satellite propagation data

Accurate estimates of the propagation impairments that affect link quality and availability and determine signal interference fields are essential for the reliable design of telecommunication systems and the efficient use of the electromagnetic spectrum. Recent announcements by commercial entities of their intent to use Ka-band spectrum to supply satellite services have heightened interest in propagation data and models for these frequencies. This paper provides a brief overview of Ka-band Earth-satellite systems and requirements in relation to the need for specific types of propagation data     

Remote sensing of land surface temperature: the directional viewingeffect

Land surface temperature and emissivity products are currently being derived from satellite and aircraft remote sensing data using a variety of techniques to correct for atmospheric effects. Implicit in the commonly employed approaches is the assumption of isotropy in directional thermal infrared exitance. The authors' theoretical analyses indicate angular variations in apparent infrared temperature will typically yield land surface temperature errors ranging from 1 to 4°C unless corrective measures are applied     

A multichannel neural probe for selective chemical delivery at thecellular level

A bulk-micromachined multichannel silicon probe capable of selectively delivering chemicals at the cellular level as well as electrically recording from and stimulating neurons in vivo has been developed. The process buries multiple flow channels in the probe substrate, resulting in a hollow-core device, Microchannel formation requires only one mask in addition to those normally used for probe fabrication and is compatible with on-chip signal-processing circuitry. Flow in these microchannels has been studied theoretically and experimentally. For an effective channel diameter of 10 μm, a channel length of 4 mm, and water as the injected fluid, the flow velocity at 11 torr is about 1.3 mm/s, delivering 100 pl in 1 s. Intermixing of chemicals, with the tissue fluid due to natural diffusion through the outlet orifice becomes significant for dwell times in excess of about 30 min, and a shutter is proposed for chronic use. The probe has been used for acute monitoring of the neural responses to various chemical stimuli in guinea pig superior and inferior colliculus     

A thermal-fully hydrodynamic model for semiconductor devices andapplications to III-V HBT simulation

Because of the interaction between self-heating and hot carriers effects, neither isothermal nor conventional macrothermal models are adequate for the simulation of state-of-the-art power devices; instead, a detailed electro-thermal model accounting for nonstationary transport, such as the Thermal-Fully Hydrodynamic (T-FH) model, is required. We apply a one-dimensional (1-D) implementation of such a model to the simulation of AlGaAs/GaAs and InP/InGaAs Heterojunction Bipolar Transistors (HBTs), comparing the results with those provided by simplified models, and highlighting how deeply both nonlocal transport and self-heating affect the predicted device performance. The importance of the convective terms is assessed, and a new nonthermal mechanism for the output Negative Differential Resistance (NDR) is proposed     

Temperature performance of 1.3-/spl mu/m InGaAsP-InP lasers with different profile of p-doping

Temperature dependencies of the threshold current, device slope efficiency, and heterobarrier electron leakage current from the active region of InGaAsP-InP multiquantum-well (MQW) lasers with different profiles of acceptor doping were measured. We demonstrate that the temperature sensitivity of the device characteristics depends on the profile of p-doping, and that the variance in the temperature behavior of the threshold current and slope efficiency for lasers with different doping profiles cannot be explained by the change of the measured value of the leakage current with doping only. The entire experimental data can be qualitatively explained by suggesting that doping ran affect the value of electrostatic band profile deformation that affects temperature sensitivity of the output device characteristics. We show that doping of the p-cladding/SCH layer interface in InGaAsP-InP MQW lasers leads to improvement of the device temperature performance.