Types Of Active Elements Research Articles

Specific Design Features of Charge Sensitive Amplifiers on Arsenide-Gallium Master Slice

For the production of integrated analog circuits with a small-scale integration, which are developed to operate at temperatures up to minus 200 ℃ and/or with absorbed dose of gamma radiation up to 5 Mrad, a gallium arsenide master slice has been created. The following types of active elements are used in this master slice: DpHEMT with gate dimensions 100 ηm/0,2 ηm and 10 ηm/0,2 ηm; p-n-p HBT, they were chosen for realization of most common analog circuits of operational amplifiers, comparators, voltage followers. Despite the small number of available DpHEMT with high transconductance for circuit synthesis and volt-ampere characteristics features of DpHEMT experimental samples, which exclude use of those transistors at low drain current, master slice give opportunity for developing charge-sensitive amplifiers (CSA) circuits with only one type of active elements – DpHEMT. At the same time, correct choice of the operating point of transistors provide development of low-noise, high-speed CSAs with better parameters than silicon CSAs for sensors with internal capacitance up to 100 pF. So, developed on GaAs master slice CSA with head DpHEMTs and ratio of the gate width to its length, equal to W/L = 2000 and W/L = 3000, characterized by current consumption ICC = 5,46 mA and ICC = 5,25 mA, rise time tR = 10,7 ns and tR = 9,6 ns, equivalent noise charge ENC = 3960 el, and ENC = 3700 el. with sensor capacitance of 50 pF, while the CSA with a head silicon p-channel junction field-effect transistor has W/L = 3870, ICC = 6,99 mA, tR = 27,7 ns, ENC = 5360 el. with the same sensor capacitance.

Speed-Torque Characteristics of Torque Motor with Tape Winding Stator

The speed-torque characteristics of a torque motor with a new type of active element – the tape winding is considered. The analytical studies of the motor speed-torque characteristics determination is difficult because it is required to take into account the distributed current flowing through the winding elements. This leads to the numerical methods application, in particular, COMSOL Multiphysics software based on the finite element method (FEM). Attention is paid to the changing of the motor developed torque in the presence of EMF created in the winding during the rotor rotation. It is shown that the motor torque with a rotor rotation frequency changing depends mainly on the nature of the distributed current lines flowing through the winding elements, despite the fact that the consumed current value changes to a lesser extent. The obtained speed-torque characteristics of the torque motor has a form similar to ones of separately excited DC motors. The research results allow assessing the expected characteristics of the motor model and are an integral part of the developed design policy of the torque motor with the tape winding stator.

Recent Advances in Active Metal Brazing of Ceramics and Process

Ceramic to metal joining has its potential applications in microelectronics packaging, metal–ceramic seals, vacuum tubes, sapphire metal windows, etc. But there are many limitations in joining this duo of materials that range from their structures, nature of bonding, physical properties to a complex phenomenon like wetting, spreading and adhesion. The current review discusses these critical issues from the aspects of thermodynamics, the role, and type of active elements, Ag–Cu–Ti brazing filler system and the reliability factors like residual stress, coefficient of thermal expansion, material reliability, pores and unbonded regions on the surface which affect the mechanical reliability of the joint.

Composite Ceramic Nd3+:YAG/Cr4+:YAG Laser Elements

We produce composite ceramic laser elements Nd3+:YAG/Cr4+:YAG using two different methods, i.e., (1) layer-by-layer uniaxial pressing in a metallic mold with sequential addition of appropriate portions of the powder; (2) stacking and pressing of previously uniaxially pressed tablets in a cold isostatic press. In lasers where composite ceramic Nd3+:YAG/Cr4+:YAG elements are used together with longitudinal diode pumping, we obtain the lasing regime for both types of active elements at a wavelength of 1,064 nm in the Q-switch mode. Lasers with ceramic composites produced by stacking and cold isostatic pressing of the previously pressed tablets demonstrate a slope efficiency (~30–33%) even higher than lasers with crystalline saturable absorber (~21%). Lasers based on ceramic composites manufactured by layer-by-layer pressing of powders have an efficiency of ~11–19%. Composites made by stacking and cold isostatic pressing of the previously pressed tablets demonstrate a generation threshold close to those in lasers with crystalline saturable absorbers.

Multifunctional Electronically Reconfigurable and Tunable Fractional-Order Filter

In this paper the authors present a multifunctional reconfigurable fractional-order filter performing a low-pass, high-pass, band-pass and band-reject transfer function. The filter is based on two types of active elements, OTA (Operational Transconductance Amplifier) and ACA (Adjustable Current Amplifier). It provides pole frequency control, depending on the values of the transconductance of the OTA elements. The quality factor is also electronically controlled, depending on the amplification of the ACA element. The order of the filter can be changed by switching the fractional-order capacitor having various values of the order. The circuit was implemented as a PCB (Printed Circuit Board) and measured in laboratory conditions. Measurement results are compared with the simulation results. The behavioural models were used for the purpose of the simulation.DOI: 10.5755/j01.eie.25.1.22732

Characterization of a Pneumatic Artificial Muscle for its application in an Active Ankle-Foot Orthosis

The training of lower limbs with robotic exoskeletons or active orthoses has proven to be an effective tool to help patients with various types of neurological movement disorders, to recover their functional ambulation capacity. A key component to achieve this purpose is the type of active element used to compensate for muscle weakness, typically observed in such locomotor disorders. Based on these considerations, this paper presents the results of an experimental test developed for calibration, tuning and behavioral identification of a commercial pneumatic artificial muscle Festo®, with view to its application as active element of an active ankle – foot orthosis prototype for human gait rehabilitation. It is expected that such prototype would enable to recover the ankle joint function in patients with Myelomeningocele. The actuator performance analysis from the achieved tests, as well as the study of gait patterns in persons with Myelomeningocele, evidence the potentiality of this actuator as an active element of a robotic exoskeleton applied to human gait rehabilitation.

Adjustable band-pass filter with current active elements: two fully-differential and single-ended solutions

Four adjustable band-pass filtering solutions are presented and also compared in this paper. Two of them are suitable for single-ended signal processing and the other two are their fully-differential equivalents. Filters are built with two types of active elements. First is a simple current follower with multiple outputs and second is a current amplifier with adjustable current gain that is used to control the quality factor of each of filters. Dependency between gain and quality factor is direct in two cases or inverse in other cases and that is why the range of adjustability varies. Simulations with CMOS-transistor structures are included. Values of quality factor obtained for each of solutions are assessed.

KHN-equivalent voltage-mode filters using universal voltage conveyors

The analog circuit design is very often focused on the design of frequency filters employing different types of active elements. In this paper we present the universal voltage conveyor that is used for the design of the KHN-equivalent filters working in the voltage-mode. Auxiliary voltage inputs of the active elements are used to reduce the number of floating admittances in the structure. Both proposed structures are easily cascadable since the input and output impedances are in theory infinitely high and zero, respectively. The behavior of the filters has been verified through PSpice simulations and furthermore by experimental measurements.

OTA based frequency tuning system with reduced effect of DC offsets

An on-line tuning system based on the master–slave technique is proposed in this paper. Each stage of the system is realized by employing only operational transconductance amplifiers (OTAs). The most significant advantage of the introduced topology is the reduction of the influence of the dc offset terms which are critical about the performance of such systems. In addition, an attractive benefit is the suitability for implementing the resulted configurations in both integrated and discrete-component forms using only the same type of active element. The validation of the proposed topology is achieved through simulation and experimental results.

Preparation and characterization of transparent Nd:YAG ceramics

AbstractTransparent Nd:YAG ceramics were produced by solid.state reaction of high.purity (4N) nanometric oxides powders, i.e., Al2O3, Y2O3 and Nd2O3. After sintering, mean grain sizes of 2% Nd:YAG samples were about 20 μm and their transparency were a bit worse than that of 0.9% Nd:YAG single crystal. Two types of active elements: rods and slabs were fabricated and characterized in several diode pumping schemes. In end pumping configuration as a pump source 20.W fiber coupled laser diode operating in low duty cycle regime (1 ms pump duration/20 Hz) was deployed. In the best case, 3.7 W of output power for 18 W of absorbed pump power, M2 < 1.4 were demonstrated for uncoated ceramics Nd:YAG rod of ϕ 4×3mm size in preliminary experiments. For the ceramics of two times lower Nd dopant level above 30% slope efficiency was achieved. In case of Nd:YAG ceramic slab side pumped by 600.W laser diode stack above 12 W was demonstrated with slope efficiency of 3.5%.

Three-dimensional self-organized microoptoelectronic systems for board-level reconfigurable optical interconnects-performance modeling and simulation

Self-organized microoptoelectronic system (SELMOS) built from three concepts - scalable film optical link multichip-module (S-FOLM), three-dimensional (3-D) microoptical switching system (3D-MOSS), and self-organized lightwave network (SOLNET)-is proposed. The feasibility of SELMOS for board-level reconfigurable optical interconnects is studied by the beam propagation method/finite difference time domain simulation focusing on three key issues; reducing size/cost of electrical to optical (E-O) and optical to electrical (O-E) signal conversion devices, tolerating alignment accuracy for optical coupling, and miniaturizing high-speed massive optical switching. S-FOLM, which consists of film-waveguide-based 3-D structures with embedded optoelectronic active elements and optical Z-connections for interplane links, enables drastic size/cost reduction of E-O and O-E conversion devices. 3D-MOSS, which is an S-FOLM with embedded microoptical switches, has a potentiality of 1024 /spl times/ 1024 switching with a system size of /spl sim/1.4 /spl times/ 0.6 cm/sup 2/ and an insertion loss of 29 dB. The switching rate of the 3D-MOSS is determined by the heat releasing speed to be /spl sim/2 /spl times/ 10/sup 5/ 1/s when PLZT waveguide-prism-deflector microoptical switches are used. By using advanced electrooptic materials, rates higher than 10/sup 8/ 1/s are expected. Twenty-five percent misalignment in waveguide assembly raises the insertion loss of the 3D-MOSS to 73 dB. The loss is reduced to 32 dB in SELMOS-based 3D-MOSS, where a self-organized 3-D microoptical network is implemented using SOLNET. Further loss reduction is expected by structural optimization of loss-inducing parts. Thus, SELMOS is found to be a solution of the three key issues for board-level reconfigurable optical interconnects. In addition, photolithographic packaging with selectively occupied repeated transfer (PL-Pack with SORT), which integrates different types of active elements into one substrate in desired arrangements using an all-photolithographic process, can contribute to cost and the coefficient of thermal expansion-mismatching reduction.

Wide Dynamic Range High Output Impedance Current-mode Multifunction Filters with Dual-output Current Conveyors

Summary This paper reports five new single-input multiple-output current-mode multifunction filter circuits which can simultaneously realise three basic filter functions all at high impedance outputs. The circuits employ only the same type of active elements, grounded passive components, andno element matching conditions are imposed. The filters permit orthogonal adjustment of the quality factor Q and angular resonant frequency ω 0 . The active/passive sensitivities are shown to be low.

Feedback charge amplifier integrated on the detector wafer

Abstract A charge sensitive preamplifier was realized on high resistivity detector grade silicon. The amplifier operates on a fully depleted bulk of a silicon wafer. As the anode region of any radiation detector operates at the full depletion as well, the possibility of direct integration of the preamplifier close to the detector anode was demonstrated. All production steps are compatible with production steps for radiation detectors. The implementation of the preamplifier is based on a new type of single sided field effect transistor which is the only type of active element in the design. The performance of single components and of the whole preamplifier is reported.

Sonar and the Fourth Dimension*

Summary THIS PAPER discusses the uses and operating principles of sonar, and describes several types of fleet sonar equipment in current use. Fundamentals of transducer design are outlined, including a discussion of the three types of active elements. Directional and range characteristics of underwater sound propagation are analyzed, and an illustrative problem presents actual calculations of sonar characteristics for a typical system.