Resistive Termination Research Articles

Selectively-undercut traveling-wave electroabsorption modulators incorporating a p-InGaAs contact layer

A novel fabrication process has been developed for fabricating undercut-etched electroabsorption modulators that are compatible with tunable lasers. This process allows for the incorporation of highly doped p-type InGaAs above the upper cladding as an ohmic contact layer. The EAM demonstrates significant improvement in the microwave performance with little effect on modulation efficiency due to the undercut etching. This device uses a traveling wave electrode design with an integrated, matched termination resistor to demonstrate a 34 GHz 3-dB bandwidth for a 600 microm long modulator.

Load sensing surgical instruments

Force and pressure sensing technology applied to smart surgical instruments as well as implants allow to give a direct feedback of loads to the surgeon lead to better reliability and success of surgical operations. A common technology used for sensors is low-cost piezoresistive thick-film technology. However, the standard thick-film firing conditions degrade the properties of medical alloys. In order to avoid this problem, the solution is to decrease the firing temperature of thick films. This work presents the development and characterisation of low-firing thick-film systems (dielectrics, resistors and conductors), formulated to achieve chemical and thermal expansion compatibility with an austenitic stainless steel medical alloy. Adherence tests and results on electrical properties of these systems: resistance, temperature coefficient of resistance (TCR) are presented. It was found that the main issue in these systems lies in mastering the materials interactions during firing, especially at the silver-based resistor terminations. The interaction of silver, resistor and dielectric tends to give rise to highly resistive zones at the terminations, affecting reliability. This can be circumvented by post-firing the resistor terminations at a moderate temperature.

GTEM 셀 설계를 위한 전자파 모델링 및 회로망 해석 기법 연구

본 논문에서는 <TEX>$DC{\sim}18\;GHz$</TEX>에서 동작하는 GTEM 셀 설계를 위한 전자파 모델링과 회로망 해석 기법을 제시하였다. GTEM 셀의 동축선 입력 급전부의 모드 변환기, 전송선 길이가 5미터인 확장형 사각 동축선 그리고 전송부 동축선의 전류와 입력단으로부터 입사되는 전자파를 정합시킬 수 있는 종단 부하로 구성되는 3차인 전자파 수치 해석 모델을 제시하였다. GTEM cell의 급전부, 전송선부, 종단 부하부에 대한 등가 회로망 모델을 제시하였으며, 이를 이용하여 전자파 수치 해석 모델에서 구해진 산란 계수로부터 GTEM cell의 성능 평가 지수인 입력 반사 계수를 계산할 수 있도록 하였다. <TEX>$DC{\sim}18\;GHz$</TEX>에서 동작하는 <TEX>$5.0{\times}2.5{\times}1.7\;m$</TEX> 크기의 GTEM cell을 설계, 제작, 성능 평가하여 제안한 기법의 효용성을 입증하였다. In this paper, the electromagnetic modeling and network analysis are proposed for design of GTEM cell operating from DC to 18 GHz. 3D electromagnetic numerical analysis models composed of the coaxial mode-converter for the feeder of GTEM cell, 5 m expanded rectangular coaxial transmission line, and the resistive termination load for current and field transmitted from the feeder are developed. Equivalent network model of feeder, transmission line, and termination load in the GTEM cell is also proposed, so the return loss of GTEM cell is calculated using S-parameters using the electromagnetic numerical analysis. To verify the proposed design method, the GTEM cell is designed, constructed and tested, with its size of <TEX>$5{\times}2.5{\times}1.7\;m$</TEX> and operating frequency of <TEX>$DC{\sim}18\;GHz$</TEX>.

Corruption of Pulsed Electric Thruster Voltage Fluctuation Measurements by Transmission Line Resonances

C = ladder network stage capacitance E = difference operator L = ladder network stage inductance ‘ = number of ladder network stages m = voltage measurement node n = ladder network node identifier, 0 n ‘ Rt = termination resistance s = Laplace variable V t = transmission line driving signal ~ Vn = Laplace transform of the voltage at any node n x = length of transmission line min = smallest wavelength present in V t ! = oscillation frequency

Transition edge sensors for bolometric applications: responsivity and saturation

Microstrip-coupled transition edge sensors (TESs) combined with waveguide-horn technology produce sensitive bolometric detectors with well-defined, single-mode beam patterns and excellent polarization characteristics. These devices are now being deployed for astronomical observations. In bolometric applications, where power levels are monitored, the critical parameter that characterizes the detection is the power-to-current responsivity sI(ω), where ω is the postdetection angular frequency. In real applications, such as on a ground-based telescope, the signal of interest is superimposed on a background such as the thermal emission from the atmosphere. The power emitted by the atmosphere changes slowly in time and these changes may change the responsivity of the detector. A detailed understanding of how sI(ω) changes as a function of applied power levels and how the TES response saturates is vital for accurate calibration of astronomical data. In this paper we describe measurements of the changes in the current flowing through a TES as a function of the circuit bias and the applied power. From these measurements we calculate the efficiency of the coupling of power into the TES from a closely thermally coupled microstrip termination resistor and we determine the zero frequency responsivity sI(0) as a function of both the circuit bias and power. The variation of the responsivity is compared with predictions of a small-signal model: for the case when the loop gain LI is high, when simplifying approximations to the full solution to the electrothermal equations apply; and using the electrothermal parameters of the TES, determined by impedance measurements, as inputs to the full model solution. We find good agreement between theory and measurement in both cases in the relevant regimes.

Electrical and Thermal Characterization of Membrane-Isolated, Antenna-Coupled, TES Bolometers for the SPIDER Experiment

We have fabricated and measured the thermal and DC electrical properties of transition-edge sensing (TES) bolometers to be employed on the SPIDER experiment, a balloon-based observatory for studying the polarization of the cosmic microwave background (CMB). The bolometers consist of Al and Ti thermistors in series and a termination resistor which couples to an on-chip, polarization sensitive, 150 GHz slot-array antenna through a superconducting microstrip transmission line. Several important parameters were measured. Transition temperature measurements were performed by measuring the Johnson noise in the Ti thermistor. Current-voltage characteristic measurements were performed at various temperatures allowing for the deduction of the thermal conductance and the temperature coefficient of resistance. Electrical noise equivalent power was measured to sub-Hertz frequencies. Finally, the time constant of the bolometers was measured within the Al and Ti transitions where electrothermal feedback speeds up the bolometer response compared with the natural time constant measured just above the Ti transition temperature. The results of these measurements are within the design specifications for SPIDER.

Application of time-frequency domain reflectometry for measuring load impedance

In this paper, we propose a new load impedance measurement system based on time-frequency domain reflectometry. The proposed system was able to measure the load impedances that were realized with using various terminal resistors and connected at the end of a cable. The experimental results show that the proposed system allows us to know where the connected terminal resistor is on the cable, and how much the impedance of the terminal resistor is. Through real experiments, it is possible for the proposed system to acquire more accurate results in wide range of impedance than conventional commercial time domain reflectometry instrument.

Miniature Continuous Coverage Antenna Array for GNSS Receivers

This letter presents a miniature conformal array that provides continuous coverage and good axial ratio from 1100-1600 MHz. Concurrently, it maintains greater than 1.5 dBic RHCP gain and return loss less than -10 dB. The four element array is comprised of two-arm slot spirals with lightweight polymer substrate dielectric loading and a novel termination resistor topology. Multiple elements provide the capability to suppress interfering signals common in GNSS applications. The array, including feeding network, is 3.5 times 3.5 times 0.8 in size and fits into the FRPA-3 footprint and radome.

Design and Implementation of an Instantaneous Turning-on Mechanism for PCs

In recent years the digital has created a need for many electronic home appliances. Some of them are redesigned from PCs and have made the physical PC invisible everywhere in our living environment. Thus System standby all the time has become an important feature for turning on a PC instantly. In this paper we use the Suspended to RAM method to replace the System off method to perform an instantaneous turning-on just like some other consumer electronics have done, and we redesign the circuit to reduce the standby power consumption of a PC. First, we use CMOS as the current switch, thus avoiding the static current consumption between chips or modules, and we turn off the USB, PS/2 and network controller power supply with the USB, PS/2 and LAN waking-up function disabled. Second, we turn off the power supply for the termination resistor of the memory modules. Third, we use the high-efficiency pulse width modulation power regulator to replace the linear power regulator. Fourth, we enlarge the value of the divider resistors for the reference voltage to reduce the leakage current. Overall, these improvements reduce the standby power consumption from 2.4 watts to 0.7 watt. In addition, our design shows that the PC can be turned on within 3 seconds by reloading the OS in the DRAM.

Non-invasive VHF injected signal monitoring in atmospheric pressure plasma and axial DC magnetron

A universal non-invasive real-time frequency domain reflectometry plasma process measurement that is independent of impedance matching network is described. The measurement is deployed on the main power transmission line of the plasma tool to detect both hardware and reflections form plasma. An illustration for atmospheric pressure plasma and axial DC magnetron plasma is given. Power handling capability is 20 (2 A×10 V) and 100 W (250 mA×400 V), respectively. Four simple equivalent electrical models in terms of transmission-line theory and frequency dependent reflection modulus (gain) are employed to analyze the DC magnetron measurement results. It is shown that the electrical length between the directional device measurement plane and the plane at which the transmission line is termination by the hardware and plasma determines the frequency response signal. The strength of the signal (depth of the zero) is found to be inversely related to the termination resistance. Information on hardware, and dynamic process-induced changes due to physical sputtering/erosion are accessible.

Optimal Termination of On-Chip Transmission-Lines for High-Speed Signaling

This paper discusses the resistive termination of on-chip high-performance interconnects. Resistive termination is effective to improve the bandwidth of on-chip interconnects, on the other hands, increases the power dissipation and the area. Therefore trade-off analysis about resistive termination is necessary. This paper proposes a method to determine the termination of on-chip interconnects. The termination derived by the proposed method provides minimum sensitivity to process variation as well as maximum eye-opening in voltage.

Transplantation of Dual Adult Kidneys Into a Recipient With Minimal Abdominal Vascular Access

Dual kidney transplantation has become increasingly utilized as a means of decreasing the organ shortage and optimizing outcomes of marginal kidneys (1). Among deceased-donor kidney transplant recipients at the University of Pittsburgh Medical Center, transplantation of dual kidneys transplants from adult donors has increased from 4% (7/04–6/05), to 11% (7/05–6/06), to 32% since 7/06. Our criteria to perform dual renal transplantation generally includes donor age ≥70 years, or younger donors with glomerulosclerosis ≥10%, and/or arterial luminal narrowing of 25% to 50%. Recipients of dual kidneys must have adequate space for the transplantation of two kidneys (either both kidneys in one iliac fossa or single bilateral kidneys), so that candidates are usually limited to those who have had one or no previous kidney transplants. We describe the transplantation of dual adult kidneys into a recipient with two previous kidney transplants (one on each side) and diffuse severe aortoiliac atherosclerosis. Two kidneys from a 68-year-old male donor who expired from a myocardial infarction were accepted as an open offer with permission to utilize as a two-for-one transplantation. The terminal creatinine and calculated CCr were 1.7 mg/dL and 70 mL/min, respectively. Kidney biopsy showed glomerulosclerosis in 14% (9/63) and 5% (3/59) of the glomeruli of each kidney, respectively, and minimal interstitial fibrosis, arteriosclerosis, and arteriolosclerosis. Pulsatile perfusion of the kidneys demonstrated terminal resistances of 30% and 32%. Three wait-listed candidates were >50 years of age. The first patient, a 55-year-old male with end-stage renal disease secondary to hypertension with two failed kidney transplants and historically high antibody levels (100% class I and II enzyme-linked immunosorbent assays), had a history of several previously positive crossmatches. He shared five human leukocyte antigen antigens with this donor. To optimize his chances of transplantation, he was included in the crossmatch and it was negative for both T and B cells. The recipient operation was performed through a midline incision with the intention of revascularizing the kidneys separately to the common iliac vessels; however, the patient had diffuse hard aortoiliac atherosclerotic disease. Attempts to isolate the distal left external iliac vessels were aborted, because the previous kidney transplant was too large to allow room for exposure. The right iliac fossa was more optimal as the previous kidney transplant was atrophic. With retraction of the ilioinguinal ligament, 4 cm segments of recipient external iliac artery and vein were isolated and were healthy enough to allow anastomosis of a segment of donor common iliac artery (Y-graft) and vein (from a different donor with a compatible blood type), respectively. The right kidney renal artery and vein were anastomosed to the internal iliac artery of the Y-graft end-to-end and the middle portion of the common iliac vein graft end-to-side. The left kidney was next revascularized by end-to-end anastomoses to the external iliac artery and vein grafts, respectively (Fig. 1. The ureters were anastomosed to the bladder using separate extravesical ureteroneocystostomies over 6F 12 cm double-J stents. The cold ischemia was 21 hr. The renal allografts functioned immediately; the creatinine is currently 1.7 at 2 months follow-up.FIGURE 1.: Iliac vessel Y-graft to dual kidney allografts.The technique described illustrates a method to transplant dual adult kidneys in recipients with suboptimal vascular access for transplantation. Liise K. Kayler Ron Shapiro Department of Surgery University of Pittsburgh Medical Center Pittsburgh, Pennsylvania Ernesto Molmenti Department of Surgery University of Arizona Tucson, Arizona

Lumped 50-&lt;formula formulatype="inline"&gt; &lt;tex&gt;$\Omega$&lt;/tex&gt; &lt;/formula&gt; Arrays of SNS Josephson Junctions

For the first time, lumped series arrays of Josephson junctions have been fabricated with a transmission line-matched 50-Omega resistance. These arrays also have the thousands of junctions necessary to produce a metrologically significant voltage. This approach is expected to increase the output voltage per array and to optimize their performance for Josephson voltage standards. Traditional Josephson arrays for voltage standards have used distributed microwave structures, where array lengths are several multiples of the driving wavelength. The lumped arrays in this work have physical lengths shorter than a quarter of the microwave drive wavelength and total normal-state resistances nearly equal to the transmission line impedance. Fabrication of these arrays was made possible by use of a newly developed Nb-(MoSi <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -Nb) <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</sub> stacked junction technology. We present measurements of the microwave response of lumped arrays with total normal resistances up to 54 Omega and with various termination resistances. A simple numerical model is presented that accounts for the spatial distribution of the microwave current and for the nonuniformity of the junction critical currents. The resulting simulations agree well with experimental results

Implementation of S-Parameter of Active Elements for FDTD Analysis

In the design of an active integrated antenna, it is necessary to analyze problems such as unwanted emissions or mutual coupling between elements. In this paper, we clarify the problems in implementing S-parameters for an FDTD analysis. Cubic spline interpolation is suitable for the construction of the S -parameter data. The implementation methods of terminal resistors and vias are examined. The proposed FDTD analysis becomes stable after correcting the discrete time lag in the formation of the incident wave. The validity of the proposed method is verified in its application to the low pass filter and the frequency tunable band pass filter.

Propagation velocity profile in a cross-section of a cardiac muscle bundle from PSpice simulation.

BackgroundThe effect of depth on propagation velocity within a bundle of cardiac muscle fibers is likely to be an important factor in the genesis of some heart arrhythmias.Model and methodsThe velocity profile of simulated action potentials propagated down a bundle of parallel cardiac muscle fibers was examined in a cross-section of the bundle using a PSpice model. The model (20 × 10) consisted of 20 chains in parallel, each chain being 10 cells in length. All 20 chains were stimulated simultaneously at the left end of the bundle using rectangular current pulses (0.25 nA, 0.25 ms duration) applied intracellularly. The simulated bundle was symmetrical at the top and bottom (including two grounds), and voltage markers were placed intracellularly only in cells 1, 5 and 10 of each chain to limit the total number of traces to 60. All electrical parameters were standard values; the variables were (1) the number of longitudinal gap-junction (G-j) channels (0, 1, 10, 100), (2) the longitudinal resistance between the parallel chains (Rol2) (reflecting the closeness of the packing of the chains), and (3) the bundle termination resistance at the two ends of the bundle (RBT). The standard values for Rol2 and RBT were 200 KΩ.ResultsThe velocity profile was bell-shaped when there was 0 or only 1 gj-channel. With standard Rol2 and RBT values, the velocity at the surface of the bundle (θ1 and θ20) was more than double (2.15 ×) that at the core of the bundle (θ10, θ11). This surface:core ratio of velocities was dependent on the values of Rol2 and RBT. When Rol2 was lowered 10-fold, θ1 increased slightly and θ2decreased slightly. When there were 100 gj-channels, the velocity profile was flat, i.e. the velocity at the core was about the same as that at the surface. Both velocities were more than 10-fold higher than in the absence of gj-channels. Varying Rol2 and RBT had almost no effect. When there were 10 gj-channels, the cross-sectional velocity profile was bullet-shaped, but with a low surface/core ratio, with standard Rol2 and RBT values.ConclusionWhen there were no or few gj-channels (0 or 1), the profile was bell-shaped with the core velocity less than half that at the surface. In contrast, when there were many gj-channels (100), the profile was flat. Therefore, when some gj-channels close under pathophysiological conditions, this marked velocity profile could contribute to the genesis of arrhythmias.

New Impedance Matching Scheme for 60 GHz Band Electro-Absorption Modulator Modules

This letter proposes a new impedance matching scheme of a traveling wave electro-absorption modulator (TWEAM) module for a 60 GHz band radio-over-fiber (ROF) link. A microstrip bandpass filter (BPF) was used to achieve impedance matching at the 60 GHz band, and termination resistance was carefully designed to obtain an input impedance close to 50 Ω. Also, a bias circuit for the device was designed in the module. The measured return loss and frequency response show that the modulator module observes the characteristics of a filter without the need of a further tuning process.

A low-voltage and variable-gain distributed amplifier for 3.1-10.6 GHz UWB systems

A low-voltage and variable-gain distributed amplifier is presented in this letter. This microwave monolithic integrated circuit amplifier achieves 12-dB gain with a 3-dB frequency band of 1.6-12.1GHz and 6.5-dB noise figure under the bias condition of 0.8-V supply voltage and 6.4-mW total dc power consumption. The gain-control range is from -18dB to +20dB. Resistive metal-oxide-semiconductor field-effect transistors are used as termination resistors to compensate the mismatch due to different bias conditions. From 3.1 to 10.6GHz, the maximum gain ripple of this amplifier is only /spl plusmn/1dB for the gain level between -4 and 20dB.

The method of waveform images for finite waveguides with resistive terminations subject to arbitrary initial conditions

Reflection at normal incidence of a plane wave can be described by imaging the incident wave profile on the opposite side of the boundary. This concept has been introduced in a few texts, but only for nondissipative conditions. In this paper the procedure to describe a purely resistive boundary is generalized, and then the concept is extended to describe the transient response of a one-dimensional, finite length waveguide. The field generated by arbitrary initial conditions is characterized by an infinite number of images, which leads to a representation of the acoustic field as oppositely propagating waves in an unbounded waveguide. Both graphical and mathematical descriptions of these waves are derived, with the former shown to provide significant insights. Mathematical analysis of the image construction leads to identification of several fundamental acoustic phenomena, including acoustic modes and reverberation time. From an instructional viewpoint the ability to explore fundamental acoustic phenomena without recourse to solving differential equations makes the waveform image concept especially useful as an introductory tool.

Resonance modes in a one-dimensional medium with two purely resistive boundaries: Calculation methods, orthogonality, and completeness

Studying the problem of wave propagation in media with resistive boundaries can be made by searching for “resonance modes” or free oscillations regimes. In the present article, a simple case is investigated, which allows one to enlighten the respective interest of different, classical methods, some of them being rather delicate. This case is the one-dimensional propagation in a homogeneous medium having two purely resistive terminations, the calculation of the Green function being done without any approximation using three methods. The first one is the straightforward use of the closed-form solution in the frequency domain and the residue calculus. Then, the method of separation of variables (space and time) leads to a solution depending on the initial conditions. The question of the orthogonality and completeness of the complex-valued resonance modes is investigated, leading to the expression of a particular scalar product. The last method is the expansion in biorthogonal modes in the frequency domain, the modes having eigenfrequencies depending on the frequency. Results of the three methods generalize or∕and correct some results already existing in the literature, and exhibit the particular difficulty of the treatment of the constant mode.

A 3-Gb/s/ch Transceiver for 10-mm Uninterrupted RC-Limited Global On-Chip Interconnects

Global on-chip data communication is becoming a concern as the gap between transistor speed and interconnect bandwidth increases with CMOS process scaling. Repeaters can partly bridge this gap, but the classical repeater insertion approach requires a large number of repeaters while the intrinsic data capacity of each interconnect-segment is only partially used. In this paper we analyze interconnects and show how a combination of layout, termination and equalization techniques can significantly increase the data rate for a given length of uninterrupted interconnect. To validate these techniques, a bus-transceiver test chip in a 0.13-/spl mu/m, 1.2-V, 6-M copper CMOS process has been designed. The chip uses 10-mm-long differential interconnects with wire widths and spacing of only 0.4 /spl mu/m. Differential interconnects are insensitive to common-mode disturbances (e.g., non-neighbor crosstalk) and enable the use of twists to mitigate neighbor-to-neighbor crosstalk. With transceivers operating in conventional mode, the chip achieves only 0.55 Gb/s/ch. The achievable data rate increases to 3 Gb/s/ch (consuming 2 pJ/bit) with a pulse-width pre-emphasis technique, used in combination with resistive termination.