Vector S-parameter measurements of the superconductingvortex flow transistor

Vector S-parameter measurements of the superconducting vortex flow transistor (VFT) are presented. The measurements were obtained for frequencies up to 100 MHz on VFTs that had a calculated transmit-time cutoff frequency of 5 GHz. An equivalent circuit model that includes calculations of the VFT transresistance, input inductance, and feedthrough capacitance is derived from these measurements. The measurements are limited to an upper frequency of 100 MHz due to crosstalk in the low-impedance system     

Input I-V and sampling time characteristics ofthe ACT device

The input I-V and sampling-time characteristics of the acoustic charge transport (ACT) device are presented for ohmic-contact charge injection and Schottky-gate-modulated charge injection. A computationally efficient analysis technique is developed to calculate the I-V and sampling-time data from two-dimensional potential and carrier-density distributions. Device physics and architecture are incorporated into the analysis through a numerical charge-injection model which is used to compute the potential and carrier-density distributions. Theoretical results are presented to demonstrate the charge injection characteristic of some typical device structures. The effects that the injection method, the epitaxial layer structure and the acoustic wave amplitude have on device performances are discussed. The physical basis of the analysis enables it to be used to study several other design parameters. Experimental measurements of a device I-V and input transconductance show good agreement with calculated data. This analysis technique provides a means of assessing the performance potential of new device designs     

Discrete-time simulation model for 1/f noise

This paper proposes a simulation model based on the fact that 1/f processes belong to the class of statistically self-similar random processes. Unlike most of the earlier modeling approaches, which were confined to the spectral domain, the model generates 1/f noise in the time domain with a simple white noise input and is parameterized by a quantity whose value can be adjusted to reflect the desired slope of the 1/f spectrum. To verify the fit between the model and actual 1/f noise measurements, experiments were conducted with a p-i-n photodiode at various bias conditions and sampling frequencies.     

LIMEX '87 ice surface characteristics: implications forC-band SAR backscatter signatures

Ice surface characterization data collected in 1987, during the Labrador Ice Margin Experiment, are analyzed to estimate the changes in snow and ice properties at the onset of melt. Surface measurements were made from an ice research vessel on several days (some of which had coincident remote sensing flights) at a number of locations in the marginal ice zone. These data are used as input parameters in a simple scattering model to simulate the effects of variations in material properties upon C-band scattering signatures     

Comparison of theoretical and measured P1dB of a photonic microwave link: influence of some physical parameters of the DFB laser

This paper studies a microwave photonic link built as an IM/DD or intensity modulation–direct detection semiconductor laser system. The radiofrequency gain and 1 dB compression point of the link are both simulated with a modelling approach and compared to measurements. The electrical model of the electro-optic transducer, a distributed feedback laser, is first presented. Taking into account the nonlinearities and noise sources, it is developed on the commercial electrical software Advanced Design System. Owing to this accurate model, the impact of the relaxation oscillation frequency is presented on the system nonlinearity characteristic as for example the input 1 dB compression point. The comparison of simulated results to measured ones confirms the accuracy of this model.     

A 1-V Class-AB Translinear Integrator for Filter Applications

In this paper, the design and measurements of a 1-volt class-AB instantaneous companding translinear integrator are presented. The use of instantaneous companding and class-AB operation gives an improvement of the dynamic range and a reduction of the power consumption. The proposed circuit uses only bipolar transistors and one capacitor and is, therefore, very well suited for integrated implementation. Its unity-gain frequency can easily be controlled by a current. Simulations and measurements of a semicustom realization, to be applied in a hearing instrument, confirm correct operation of the designed circuit. The translinear integrator operates from a single supply voltage down to 0.95 V. The current consumption is less than 1.9 A for an input current of 180 nA (p). The dynamic range is better than 73 dB over a bandwidth of 8 kHz.     

Fiber-optic reflection measurements using OCWR and OTDR techniques

A method for determining the backscatter and reflection responses of an optical fiber and reflector to an arbitrary input is developed. Two cases are specifically considered: a continuous-wave input and a rectangular pulse input. From the rectangular pulse input response, the equation is derived for computing the reflectance of a discrete component from an optical time-domain reflectometer (OTDR) measurement. Precautions are given for accurately performing reflectance measurements using an OTDR. Two methods are presented for determining the backscatter level of the fiber type under test, and its importance in reflection measurements is shown     

A Simple Analytical Model for the Envelope Distribution of a Sinusoidal Carrier in Atmospheric Radio Noise

A recent article by Omura and Shaft [1] proposed modeling atmospheric radio noise as a narrow-band process having a lognormal envelope distribution. Based on such a model, an approximate expression is derived for the envelope probability distribution of a sinusoidal carrier in atmospheric radio noise. The results are compared with measured distribution of the instantaneous amplitude out of a wide-band envelope detector Watt and Plush [2], and show good agreement over the range of input carrier-to-noise ratios for which measurements were made.     

Dynamic model-based filtering for mobile terminal location estimation

Mobile terminal location is an important area of research because of its applications in location-sensitive browsing and resource allocation. The paper presents a method for reducing the error in mobile terminal location estimation. A preprocessor using nonparametric estimation is used to reduce the effects of non-line-of-sight and multipath propagation on the location procedure. A model-based dynamic filter is presented that uses an accurate model of mobile terminal motion to combine information from location measurements made at different time instances to create an improved location estimate. The model of mobile terminal motion has a kinematic state space model describing the physical rules governing terminal motion and a control model that describes the human control input into the motion process. Location dependency in the control input model is used to derive a new dynamic filter. This filter provides greatly improved accuracy over previously known location techniques and is much more robust to variations in the mobile terminal motion and nonlinear effects in the propagation environment.     

1/f noise synthesis model in discrete-time for circuit simulation

Flicker noise, popularly known as 1/f noise is a commonly observed phenomenon in semiconductor devices. To incorporate 1/f noise in circuit simulations, models are required to synthesize such noise in discrete time. This paper proposes a model based on the fact that 1/f processes belong to the class of statistically self-similar random processes. The model generates 1/f noise in the time domain (TD) with a simple white noise input and is parameterized by a quantity whose value can be adjusted to reflect the desired 1/f parameter, that is, the slope of the 1/f spectrum. It thus differs from most of the earlier modeling approaches, which were confined to the spectral domain. To verify fit between the model and actual 1/f noise measurements, experiments were conducted using discrete devices such as a PIN photodiode at various bias conditions and sampling frequencies. The noise synthesized by the model was found to provide a good match to the measurements. Furthermore, it is demonstrated that the proposed 1/f noise model can also be incorporated in circuit simulations as a noise current or noise voltage source, which was not feasible earlier with the conventional spectral domain representation. To validate the inclusion of 1/f noise in circuits as TD current or voltage, simulations were carried out on a CMOS ring oscillator and the clock jitter due to 1/f noise was investigated.     

Theory and experiment of In1-xGaxAsyP1-y andIn1-x-yGaxAlyAs long-wavelengthstrained quantum-well lasers

We present a comprehensive model for the calculation of the bandedge profile of both the In_1-xGa_xAs_yP_1-y and In_1-x-yGa_xAl_yAs quantum-well systems with an arbitrary composition. Using a many-body optical gain model, we compare the measured net modal gain for both material systems with calculations from the realistic band structure including valence band mixing effects. Calibrated measurements of the side light spontaneous emission spectrum based on its fundamental relation to the optical gain spectrum give values for the radiative current density. These measurements allow us to extract the relationship between total current density and carrier density. A fit of this relation yields values for the Auger coefficient for each material system     

InGaAsP channel HFET's on InP for OEIC applications

A model for the calculation of the input noise of a high impedance photoreceiver is proposed, taking into account the contributions of low-frequency characteristics of the FET. Simulations based on this approach show that excess gate leakage current and low-frequency excess noise, usually observed in InGaAs channel FET's, strongly penalize the photoreceiver sensitivity for low to medium data rates. New InGaAsP channel HFET's have been developed and fabricated to solve those problems, dc measurements on 1×100 μm² gate HFET's show good I_ds-V_ds characteristics with associated gate leakage currents lower than 200 nA. Promising ft of 18 GHz and f _max of 40 GHz have been recorded on 0.5×200 μm² gate transistors. Low-frequency gate and channel noise measurements demonstrate the suitability of InGaAsP channel HFET structure and technology for low noise applications. A hybrid pin-HFET high impedance photoreceiver has been assembled with a 1×150 μm ² gate transistor. A very close agreement is found between photoreceiver input noise predicted by our model and experimental results. Record sensitivities of 34.8 dBm at 622 Mbit/s and -28.7 dBm at 2.5 Gbit/s are inferred from noise measurements, confirming the strong potential of InGaAsP channel HFET's for the fabrication of high sensitivity photoreceivers operating at moderate data rates     

12-bit low-power fully differential switched capacitornoncalibrating successive approximation ADC with 1 MS/s

Based on a conventional successive approximation ADC architecture, a new and faster solution is presented. The input structure of the new solution consists of transmission gates and capacitors only and there is no need for any active element. A switching circuit is implemented to allow a wider input voltage range of the ADC. Together with a self-timed comparator, the power consumption is noticeably reduced while at the same time the sampling rate is doubled. Smaller input and reference capacitances reduce the requirements on the input and reference sources, respectively. Additionally, a widely clock-duty-cycle-independent control logic improves the applicability of the converter cell, especially for systems on chip. Results of measurements confirm the theoretical improvements     

Architecture and algorithms for tracking football players with multiple cameras

A system architecture and method for tracking people is presented for a sports application. The system input is video data from static cameras with overlapping fields-of-view at a football stadium. The output is the real-world, real-time positions of football players during a match. The system comprises two processing stages, operating on data from first a single camera and then multiple cameras. The organisation of processing is designed to achieve sufficient synchronisation between cameras, using a request-response pattern, invoked by the second stage multi-camera tracker. The single-view processing includes change detection against an adaptive background and image-plane tracking to improve the reliability of measurements of occluded players. The multiview process uses Kalman trackers to model the player position and velocity, to which the multiple measurements input from the single-view stage are associated. Results are demonstrated on real data.     

Extracellular Potential Recordings by Means of a Field Effect Transistor Without Gate Metal, Called OSFET

The design and operation of a new semiconductor element, based upon the field effect principle is discussed. The device, which is called an OSFET, can be used as a measuring electrode for bioelectric activity. The OSFET consists of an MOS-transistor configuration, where the gate metal has been omitted and can be used directly in the extracellular fluid as an active probe. The operation of the OSFET is described by a physical-mathematical model, by means of which it is possible to explain the results of electrophysiological measurements. These results are compared with the results of a computer simulation, in which the Rosenfalck equation for extracellular potential distributions serves as an input for the OSFET model stated. A special electronic circuit is used to perform low impedance measurements in a simple way with the OSFET electrode. It appears that extracellular potentials measured with an OSFET-electrode have an extended frequency range, with respect to conventional potential measurements (0 ?< f ?< 45 K c/s).     

Simple model of optical amplifier chains to evaluate penalties inWDM systems

A simple model to evaluate the penalty due to amplifier gainshape in a wavelength division multiplexing (WDM) optical system is proposed. The model requires only knowledge of the overall gain of the amplifier chain for all channels and provides signal-to-noise ratio (SNR) penalties for given launched powers. It also provides the input power distribution required for SNR equalization, and the associated SNR penalty, by solving an eigenvalue/eigenvector problem. The penalty predicted by the model agrees well with recent field measurements on a transoceanic cable. The model can also be applied to predict the gainshape of the amplifier chain from a measurement of the output noise spectrum with no input signal. The capacity of a long amplifier chain can thereby be determined from the receiving terminal only     

Antenna Effective Aperture Measurement With Backscattering Modulation

A scattering measurement method for antenna characterization is described. The antenna backscattering is modulated by an oscillator circuit. The modulation begins, when a known RF power is transferred to the oscillator circuit from the antenna. This enables the measurement of the effective aperture of the antenna, from which the antenna bandwidth and radiation pattern are obtained. A theory for antenna aperture measurement is developed using a simple circuit model for the antenna-oscillator system. A dipole and a PIFA with a reactive input impedance at the application frequency were measured. The antenna aperture was measured to an accuracy of 9%, and the measurements complied with simulated and measured references. The method provides simple and accurate bandwidth and radiation pattern measurements with the reactive load the antenna is designed to work with.     

The estimation of tube wall compliance using acoustic inputimpedance

An acoustic-electric analog and transmission line theory have been used to examine acoustic wave propagation in a tube with a compliant wall. The input impedance (i.e., input pressure-flow) has been simulated using a distributed element model. A relative minimum and maximum, denoted by fr and f2, respectively, that are independent of tube length have been identified theoretically and confirmed experimentally from input impedance measurements on a compliant tube. A method has been devised which uses measured values of fr and f2 to deduce the tube wall properties from the theoretical model. This method has been validated on a tube with known wall properties determined using standard methods. In practice, the input impedance is measured through a short section of rigid connecting pipe. In this case fr remains constant while f2 is reduced. This reduction can be accounted for by the volume compliance of the gas within the lumen of the rigid pipe. The theory could have useful applications such as estimating the wall properties of the airways from noninvasive measurements made through the mouth.     

SCR-Controlled DC-Motor Model for an Electric Vehicle Propulsion System Simulation

A model of a silicon-controlled rectifier (SCR) dc-series wound motor drive is described and evaluated. The model, developed for use in a digital simulation of an electric vehicle (EV), requires a minimum number of input parameters while taking into account the fluctuating nature of the flow of motor current. The equations derived are solved explicitly for motor current, thus giving an efficient computer implementation. The control input to the model is the duty cycle of the switching waveform to the SCR. The output from the model is average motor torque. The results are valid over the ranges of frequency and duty cycle typically used in EV motor drives. A generalized formulation, which will accept a nonlinear magnetic flux characteristic, is derived and applied in the simulation of an EV driven by a 42-hp dc traction motor. All relevant simulation model parameters were taken from an EV used in a series of field tests. Experimental measurements of motor current demand over a complex driving cycle were compared with a corresponding set of simulation results. Agreement between the two sets of results was found to be good.     

2.5 V passive CMOS mixer with 20 dBm P1 dB compression

A passive CMOS downconversion mixer with LO buffer is presented in 0.25 μm SiGe BiCMOS using a 2.5 V supply. With a 60 MHz RF signal input, measurements show that the conversion loss is 2.9 dB, the input-referred 1 dB compression point is 20 dBm and the inputreferred noise is 2146.8 dBm/Hz. Compared to conventional NMOS mixers, the 1 dB compression point is improved by 9.7 dB. The tradeoffs and the design of the LO buffer, which has a strong impact on the intermodulation distortion, are also presented.