Measurement of Passive $R$, $L$, and $C$ Components Under Nonsinusoidal Conditions: The Solution of Some Case Studies

This paper deals with the measurement of the R, L, and C parameters of passive components in nonsinusoidal conditions. Since these components usually work with voltage and current waveforms that are different from sinusoidal ones, nonsinusoidal characterization has to be made. The importance of nonsinusoidal characterization of passive components is highlighted through the analysis of two case studies: (1) the influence of distorted waveforms on the line impedance stabilizer network (LISN) passive component behaviors and (2) the influence of voltage and current harmonics on hybrid filter responses. In this paper, the authors propose and describe a measurement method based on linear system identification and model parameter estimation techniques. Then, the two case studies are analyzed and described with the help of some test results.     

Error Tolerant DNA Self-Assembly Using ( $hbox{2}k-hbox{1}$)$times$( $hbox{2}k-hbox{1}$) Snake Tile Sets

DNA self-assembly has been advocated as a possible technique for bottom-up manufacturing of scaffolds for computing systems in the nanoscale region. However, self-assembly is affected by different types of errors (such as growth and facet roughening) that severely limit its applicability. Different methods for reducing the error rate of self-assembly using tiles as basic elements have been proposed. A particularly effective method relies on snake tile sets that utilize a square block of even size (i.e., 2k times 2k tiles, k = 2, 3,.. .). In this paper, an odd-sized square block [i.e., (2k -1) times (2k - 1)] is proposed as basis for the snake tile set. Compared with other tile sets, the proposed snake tile sets achieve a considerable reduction in error rate at a very modest reduction in growth rate. Growth and facet roughening errors are considered and analytical results are presented to prove the reduction in error rate compared with an even-sized snake tile set. Simulation results are provided.     

Design and Characterization of a Sampling System Based on $Sigma$–$Delta$ Analog-to-Digital Converters for Electrical Metrology

This paper describes a sampling system designed using a commercial sigma–delta analog-to-digital converter ($Sigma$–$ Delta$ ADC). In addition to characterization measurements using a conventional high-quality signal generator, a Josephson waveform synthesizer that provides ultimately noise- and drift-free voltages was used. To evaluate the suitability of this sampling system as part of a transfer power standard, additional comparisons of the root-mean-square (RMS) values measured were performed against a thermal converter and the primary power sampling standard at the Physikalisch-Technische Bundesanstalt, Braunschweig, Germany. Initial analysis of the measurement data shows an effective resolution in the range of 18–19 bits at an equivalent sampling rate of 64 kHz. The integral nonlinearity error of the system was measured to be within $pm 7 mu hbox{V/V}$ or one least significant bit at this resolution.      

Measuring $I/Q$ Impairments in WiMAX Transmitters

This paper presents a new method for measuring the I /Q impairments affecting the worldwide interoperability for microwave access (WiMax) transmitters through the analysis of the signal acquired through a general-purpose I /Q receiver. Based on a model of the effects of the I /Q impairments on the output signal that is suitable for orthogonal frequency-division multiplexing (OFDM) systems like WiMax, the method is designed to correctly take into account the peculiarities of systems compliant with the IEEE 802.16-2004 standard, such as the potentially noxious effects of the impairments on signal normalization and threshold decisions. The results of the experiments carried out on the standard-compliant signals are given.     

Measuring Time-Varying $I/Q$ Impairments in Digital Transmitters

Impairments affecting the baseband modulator of digital transmitters, which are commonly called I/Q impairments, are responsible for the deviations of symbols from their original position on the I/Q diagram. They cause a reduction in the noise margin and ultimately worsen the probability of error. This is why their measurement is so important in all stages in the life cycle of digital transmitters. This paper presents an original method for the evaluation of the I/Q impairments based on a discrete extended Kalman filter (DEKF). In the same way as alternative solutions already presented in the literature, the method exhibits good performance in the presence of time-invariant impairments. Differently from them, it allows accurate measurements of time-varying impairments, thus making real-time tracking of their evolution feasible. After a few theoretical notes on the I/Q impairments and DEKF, the operative stages of the proposed method are described in detail. Several experiments are then conducted on radio frequency signals to assess the performance of the method; the obtained results are given and discussed.     

A $t$-Norm-Based Fuzzy Approach to the Estimation of Measurement Uncertainty

From a metrological point of view, a measurement process rarely consists of a direct measurement but, rather, of digital signal processing (DSP) performed by one or more instruments. The measurement algorithm makes the numerical results available as functions of acquired samples from input signals. Moreover, when repeated direct measurements are performed, one may speak about interactions in subsequent results (and it may be dependent on the type of instrument being used). With mathematical formalism, the complex relations involved can be described, although again, an indirect measurement result would be obtained. Regardless, no matter what kind of process is being examined, the distribution of the uncertainty associated with the measurement needs to be known. To express a measurement result with its associated uncertainty, the recommendations of the ISO Guide need to be met. Many published papers have proposed the use of fuzzy intervals to describe both the systematic and statistical effects of repeated measurements on the distribution of their results. In this paper, we use a random-fuzzy model, the single measure is represented as a fuzzy set, and the propagation of the possibility distribution through the DSP stage (which simply consists of an average operation) is performed using the extension principle of Zadeh based on a particular triangular norm: the so-called Dombi's.     

A 1.2-V CMOS $RC$ Oscillator for Capacitive and Resistive Sensor Applications

An accurate self-adjusting CMOS $RC$ oscillator for capacitive and resistive sensor applications has been designed and manufactured. The oscillator operates with supply voltages from 1.2 to 3 V and achieves an internal accuracy of $pm$ 0.7% with a temperature range from $-20 ^{circ}hbox{C}$ to 60 $^{circ}hbox{C}$. The $RC$ oscillator was fabricated in a 0.35- $muhbox{m}$ standard n-well CMOS process with threshold voltages of 0.5 and $-$0.65 V. Its design and operation are described, and results of measurements performed on the fabricated chips are presented.      

A $di/dt$ Compensation Technique in Delay Testing by Disconnecting Power Pins

Scan-based delay testing increases power consumption, particularly peak power, due to excessive simultaneous signal switching. The instantaneous current changes increase the ground level during signal switching, slowing down the operational speed. When the switching activity increases during test operations, it is necessary to pay special attention to determine whether the speed failures are due to extra switching, since the blind application of delay testing can greatly affect the yield of a device. This paper demonstrates that cycle time adjustment is best suited to compensate for the timing issues resulting from the higher switching activity in delay testing. In the proposed method, the power pins are disconnected in an increasing number to find a proper level of cycle period adjustment. The power pins of a chip are experimentally disconnected to observe the ground bounce behavior, which is also demonstrated in simulations. The experimental results also demonstrate that the proposed method can avoid the problem of abandoning good devices by cycle adjustment.     

SiGe/Si Quantum-Dot Infrared Photodetectors With ${bm delta}$ Doping

The multicolor absorption of MOS SiGe/Si quantum-dot (QD) infrared photodetectors is demonstrated using the boron $delta$-doping in Si spacers. The energy-dispersive X-ray spectroscopy shows that the Ge concentration in the wetting layers is much smaller than that in QDs. Most holes stay at the ground state in QDs instead of wetting layers. The energy band structure in QDs is calculated to understand the absorption spectrum. The absorption at 3.7–6 $mu$m is due to the intersubband transition in the SiGe QDs. The other absorption at 6–16 $mu$ m mainly comes from the intraband transition in the boron $delta$ -doping wells. Since the broadband spectrum covers most of the atmospheric transmission windows for infrared, the broadband detection is feasible using this device.      

On the Calibration of DA Converters Based on $R/beta R$ Ladder Networks

In this paper, we discuss the possibility of realizing high-accuracy digital-analog(DA) converters by exploiting the properties of R/betaR (beta > 2) ladder networks. Extensive simulations demonstrate that, if a proper value of beta is chosen, high accuracy can be obtained by resorting to a very simple self-calibration algorithm. This is true, even in the case of large tolerance values for the resistors that make up the ladder network. Such a result may allow the design of a high-accuracy very low cost converter. The effect of the offset of the comparator needed for the self-calibration algorithm is also discussed.     

Characterization of the Temperature Dependence of the Piezoresistive Coefficients of Silicon From ${-}150,^{circ}$C to ${+}125,^{circ}$C

Stress sensing test chips are widely utilized to investigate integrated circuit die stresses arising from assembly and packaging operations. In order to utilize these test chips to measure stresses over a wide range of temperatures, one must have values of six piezoresistive coefficients for n- and p-type silicon over the temperature range of interest. However, the literature provides limited data over the desired range, and even the data at room temperature exhibit wide discrepancies in magnitude as well as sign. Thus, this work focuses on an extensive experimental study of the temperature dependence of the fundamental piezoresistive coefficients, pi₁₁, pi₁₂, and pi₄₄, for both p- and n-type silicon from -150degC to +125degC, as well as a number of useful combined coefficients. Measurements were performed using stress sensors fabricated on (001) silicon. In order to minimize errors associated with misalignment with the crystallographic axes on (001) silicon wafers, anisotropic wet etching was used to accurately locate the axes. Four-point bending (4PB) was used to generate the required stress in strip-on-beam samples, and finite-element simulations were used to determine the states of stress in the silicon material.     

Thermal Diffusivity and Related Properties of Colossal Magnetoresistive La$_{0.67}$Ca$_{0.33}$MnO $_{3}$ With Various Grain Sizes

Using the open-cell photoacoustic technique, we have measured the room-temperature thermal diffusivities of the colossal magnetoresistive material La$_{0.67}$Ca$_{0.33}$MnO$_{3 }$, sintered between 1100$;^{circ}$ C and 1350$;^{circ}$ C, with average grain sizes 1, 3, 5, and 10 $mu$m. We obtained the thermal diffusivities by analyzing the phase of photoacoustic signals in thermally thick samples using Calderon's method. We found that the insulator-metal transition temperature does not depend on the grain size ($T_{rm IM} sim 272$ K). However, the thermal diffusivity increases with grain size, with values between 0.431 and 0.969 mm $^{2}$s $^{-1}$. Other related electrical and thermal properties, including the electrical conductivity, thermal conductivity, and phonon mean free path, are also dependent on the grain size. The electronic contribution to the thermal conductivity is 2%–3% of the total thermal conductivity for smaller grain sizes (1–5 $mu$m) and increases to about 24% when the grain size is increased to 10 $mu$ m.      

Bit Storage by 360 $^{circ}$ Domain Walls in Ferromagnetic Nanorings

We propose a theoretical design for a magnetic memory cell, based on thin-film ferromagnetic nanorings, that can efficiently store, record, and read out information. An information bit is represented by the polarity of a stable 360$^{circ}$ domain wall introduced into the ring. Switching between the two magnetization states is done by a current applied to a wire passing through the ring, whereby the 360$^{circ}$ domain wall splits into two charged 180 $^{circ}$ walls, which then move to the opposite extreme of the ring to recombine into a 360 $^{circ}$ wall of the opposite polarity.      

Comparison of the ${mbi A}^{*}{-}{mbi A}$ and ${mbi T}, Phi{-}Phi$ Formulations for the 2-D Analysis of Solid-Rotor Induction Machines

We present two eddy-current field potential formulations to solve rotating electrical machine problems by applying the finite-element method (FEM) using the motional ${mbi A}^{*}{-}{mbi A}$-potential formulation and the motional ${mbi T}, {bf Phi}{-}{bf Phi}$-potential formulation. We use the single-phase and three-phase solid-rotor induction motors of Problem No. 30a of TEAM Workshops to compare the potential formulations. We have solved both problems in the time domain and the frequency domain.      

A Very Low Offset Preamplifier for Voltage Measurements in the $muhbox{V}$ Range

A new topology for the implementation of a very low offset voltage preamplifier is presented. The new topology employs a time-varying resistance as a probe for detecting the sign and magnitude of the equivalent input offset of an operational amplifier in a series-shunt feedback configuration and allows for continuously correcting the offset voltage by means of a proper control feedback. The most remarkable feature of the approach we propose is the fact that the offset correction can continuously be performed with the signal voltage source connected to the circuit, as its presence and magnitude do not affect the offset detection circuit. At the same time, the offset cancellation circuit has minimum effect on the output voltage of the preamplifier in the bandwidth of the signal. An actual low-offset preamplifier based on the new approach we propose has been built and tested. While employing a metal–oxide–semiconductor field-effect transistor (MOSFET) input operational amplifier with a typical input offset of 100 $muhbox{V}$ (600- $muhbox{V}$ maximum), a voltage preamplifier with a gain of 201 and an equivalent input offset voltage below 100 nV is consistently obtained, which is independent, by design, of the temperature. While characterized by these excellent performances, the system employs quite standard low-cost components and does not require any calibration procedure.      

Spin Seebeck Effect in Ni$_{81}$Fe$_{19}$/Pt Thin Films With Different Widths

The spin Seebeck effect (SSE) has been measured in Ni $_{81}$Fe $_{19}$ thin films which have different widths by using the inverse spin Hall effect (ISHE) in a Pt wire. The ISHE voltage induced by SSE is enhanced by lengthening the Pt wire. Combined with ISHE, SSE is applicable to the production of electric generators in which the thermoelectric figures of merit are tunable in terms of device structure.      

Development of a High-k Pr $_{2}$O $_{3}$ Sensing Membrane for pH-ISFET Application

In order to develop a pH sensor having a good pH-sensing characteristic, electrolyte-insulator-semiconductor capacitors using a high-k Pr$_{2}$O$_{3}$ thin film as the sensing membrane were fabricated on silicon substrates by reactive radio frequency sputtering. The structural and morphological features of these films with annealing at various temperatures were studied by X-ray diffraction, atomic force microscopy, and X-ray photoelectron spectroscopy. The Pr$_{2}$O $_{3}$ sensing film after annealing at 900$;^{circ}$C is suggested to the increase in the interfacial SiO $_{2}$ and silicate formation, and the high surface roughness. Therefore, a physical vapor deposition Pr$_{2}$O $_{3}$ film is adopted as a new pH-sensing layer. The result produces a pH response of 52.9 mV/pH $({rm pH}=2hbox{--}12)$, a hysteresis voltage of 17.5 mV $({rm pH}=7 to 4 to 7to 10 to 7)$, and a drift rate of 2.15 mV/h (${rm pH}=7$ buffer solution).      

Electric Field Sensing Scheme Based on Matched $ hbox{LiNbO}_{3}$ Electro-Optic Retarders

In this paper, a wideband-electric-field-sensing scheme that uses optically matched integrated optics electrooptic devices and coherence modulation of light is described. In a coherence modulation scheme, the integrated optics sensor detects the electric field and imprints it around an optical delay. The optical delay is generated by a birefringent optical waveguide in a lithium niobate (LiNbO₃) integrated optics two-wave interferometer. The modulated optical delay, acting as an information carrier, is transmitted through an optical fiber channel. At the receiver, light is demodulated by a second integrated optics two-wave interferometer, which also introduces a second optical delay. The optical delays on the sensor and demodulator are matched at the same value. The integrated optics demodulator measures the autocorrelation of light around the optical delay value, and the imprinted electric field is recuperated as a linear variation of the received optical power. The matching of the sensor and demodulator allows a direct detection of the electric field, giving a unique feature to this fiber-integrated optics scheme. The experimental setup described here uses two pigtailed LiNbO₃ electrooptic crystals: one acting as the electric field sensor and the other acting as the optical demodulator. The wideband sensing range on the experimental setup corresponds to frequencies between 0 and 20 kHz.     

Eddy-Currents Computation With T-$Omega$ Discrete Geometric Formulation for an NDE Problem

We propose a discrete geometric formulation based on a magnetic scalar potential and on the circulation of an electric vector potential to solve eddy-current problems for nondestructive evaluation of steel bars with longitudinal defects.