Bias Network Research Articles

PIN 다이오드를 이용한 다중 편파 재구성 마이크로스트립 안테나

본 논문에서는 S-밴드에서 하나의 급전 회로로 4개의 편파(수직 편파, 수평 편파, 좌선회 편파, 우선회 편파)를 선택적으로 사용할 수 있는 다중 편파 재구성 마이크로스트립 안테나를 제안하였다. 제안된 안테나는 십자 슬롯과 원형 슬롯을 포함하는 정사각형 형태의 마이크로스트립 패치와 4개의 PIN 다이오드로 구성되어 있으며, 커플링을 통한 급전 방식을 이용한다. 각각의 PIN 다이오드에는 직류 전압을 인가하기 위한 바이어스 단이 있으며, 직류 전압의 인가에 따른 다이오드 ON / OFF 동작으로 편파를 재구성할 수 있다. 제작된 안테나는 수직 편파(3.17~3.21 GHz), 수평 편파(3.16~3.20 GHz), 좌선회 편파(3.08~3.19 GHz), 우선회 편파(3.10~3.20 GHz)에서 VSWR 2:1을 만족하며, 선형 편파에서는 20 dB 이상의 교차 편파 및 5 dBi 이상의 이득 특성을 갖고, 원형편파에서는 50 MHz 이상의 3 dB 축비 특성을 나타낸다. In this paper, a multi polarization reconfigurable microstrip antenna that can be used selectively for four polarizations(vertical polarization, horizontal polarization, right hand circular polarization, left hand circular polarization) at the S-band is presented. The proposed antenna consists of four PIN diodes and a microstrip patch with a cross slot and a circular slot and is fed by utiliting electromagnetic coupling between the microstrip patch and the feed line. The proposed antenna has a DC bias network to supply DC voltage to each PIN diode and the polarization can be determined by controlling the ON /OFF states of four PIN diodes. The fabricated antenna has a VSWR below 2 in the vertical polarization(3.17~3.21 GHz), the horizontal polarization(3.16~3.20 GHz), the left hand circular polarization (3.08~3.19 GHz), and the right hand circular polarization(3.10~3.2 GHz) frequency bands. The designed antenna has the cross polarization level higher than 20 dB, a gain over 5 dBi for the linear polarization states, and 3 dB axial ratio bandwidth wider than 50 MHz in the circular polarization states.

Study of a Low-Profile 2.4-GHz Planar Dipole Antenna Using a High-Impedance Surface With 1-D Varactor Tuning

A theoretical and experimental study has been performed on a low-profile, 2.4-GHz dipole antenna that uses a frequency-selective surface (FSS) with varactor-tuned unit cells. The tunable unit cell is a square patch with a small aperture on either side to accommodate the varactor diodes. The varactors are placed only along one dimension to avoid the use of vias and simplify the dc bias network. An analytical circuit model for this type of electrically asymmetric unit cell is shown. The measured data demonstrate tunability from 2.15 to 2.63 GHz with peak gains at broadside that range from 3.7- to 5-dBi and instantaneous bandwidths of 50 to 280 MHz within the tuning range. It is shown that tuning for optimum performance in the presence of a human-core body phantom can be achieved. The total antenna thickness is approximately λ/45.

Compact Frequency-Reconfigurable Half-Mode Substrate-Integrated Waveguide Antenna

A frequency-reconfigurable antenna based on half-mode substrate-integrated waveguide (HMSIW) technology for size reduction is presented. Its resonant frequency is electronically controlled by a varactor-loaded interdigital capacitor on the top plate of the HMSIW, and the bias network is designed on the bottom plate. Its performance is demonstrated experimentally, with the resonant frequency varied from 2.99 to 3.59 GHz by changing the bias voltage from 0 to 30 V.

Polarization-Reconfigurable Omnidirectional Antenna Combining Dipole and Loop Radiators

This letter proposes the development of a polarization-reconfigurable omnidirectional antenna combining a dipole and a loop radiators. The omnidirectional circular polarization (CP) waves can be generated in the azimuthal plane by adopting two metal probes act as the dipole and printed spoke-like metal strips fabricated on two substrates that act as the loop. There are 48 p-i-n diodes placed on the two substrates to alter the current direction of the loop, which makes the antenna polarization reconfigurable. The polarization states of this antenna can be switched between left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). The antenna is fed by a microstrip line, and the feeding substrate also contains a transition part and dc bias network in it. The measured -10-dB impedance bandwidth is about 18% and 14%, and the average axial ratio (AR) in the azimuthal plane is less than 3 dB for both RHCP and LHCP. The proposed antenna is designed at 1.575 GHz, such that it can be utilized for global position systems.

A VARACTOR-TUNABLE HIGH IMPEDANCE SURFACE FOR ACTIVE METAMATERIAL ABSORBER

One varactor-tunable High Impedance Surface (HIS) is proposed and used in design of an active metamaterial absorber. The proposed HIS structure is based on mushroom-type HIS, in which varactors are introduced to adjust the efiective capacitance and tune the resonance frequency. The primary ground plane is etched as the bias network for these loaded varactors, and another ultra-thin grounded sheet is attached to the bottom. In addition, the absorbing characteristics are introduced for dielectric loss to construct an active metamaterial absorber. Numerical simulations show that a wide tuning range can be achieved by adjusting the varactor capacitance, and efiective absorption is realized at difierent states. Two identical absorbers, which are loaded with flxed-value chap capacitors of difierent capacitances, are fabricated and measured using a waveguide measurement setup. Excellent agreement between the simulated and measured results is demonstrated.

Adaptive synchronization of master-slave large-scale systems against bias actuators and network attenuations

This paper utilizes the adaptive technique to design a class of active synchronizing masterslave large scale systems against imperfect actuators and networked interconnections with bias faults and signal attenuations, respectively. Without the requirement of knowledge of eventual faulty factors of bias-actuators on systems, and attenuation factors of connected networks, an adaptive mechanism is designed to estimate each unknown faulty factor on-line for constructing a class of distributed adaptive controllers. Then based on the adaptive adjustment parameters and Lyapunov stability theory, Lyapunov functions are addressed to prove that the proposed adaptive master-slave large-scale system can be guaranteed to be asymptotic synchronization with the improper actuator and faulty transmitted signals. Finally, a multiple vehicle large-scale system is used to verify the efficiency of the method.

A Pattern Reconfigurable Null Scanning Antenna

The design, analysis, and measurement of a reconfigurable null scanning antenna operating at 2.4 GHz are presented. Unlike existing null reconfigurable antennas, this compact antenna scans its pattern null continuously, and maintains its impedance bandwidth without the need for feed reconfiguration. Incorporation of 12 varactors enables null reconfiguration. Full-wave simulations of the antenna, including the bias network and the lumped circuit model for the varactors, predict antenna performance. Impedance and pattern measurements verify simulated results.

Design of low voltage, low power CMOS low noise amplifier for 2.4 GHz wireless communications

In this letter, design of a low voltage, low power CMOS low noise amplifier (LNA) for 2.4 GHz wireless communications is presented by using TSMC 0.18-μm technology. The current reused architecture is adapted to reduce the consumed current, while the supply voltage is set to 0.6 V to meet the low voltage requirement as well. To simplify the bias network designs under low voltage operations, NMOS and PMOS devices are used with three-stage configuration to enhance the gain performance. The measured results of the designed LNA show 17.7 dB in gain and 3.9 dB in noise figure with 0.86 mW of power consumption. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2849–2852, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27214

Slow dynamics and high variability in balanced cortical networks with clustered connections

Anatomical studies demonstrate that excitatory connections in cortex are not uniformly distributed across a network but instead exhibit clustering into groups of highly connected neurons. The implications of clustering for cortical activity are unclear. We studied the effect of clustered excitatory connections on the dynamics of neuronal networks that exhibited high spike time variability owing to a balance between excitation and inhibition. Even modest clustering substantially changed the behavior of these networks, introducing slow dynamics during which clusters of neurons transiently increased or decreased their firing rate. Consequently, neurons exhibited both fast spiking variability and slow firing rate fluctuations. A simplified model shows how stimuli bias networks toward particular activity states, thereby reducing firing rate variability as observed experimentally in many cortical areas. Our model thus relates cortical architecture to the reported variability in spontaneous and evoked spiking activity.

Measurement of the paraelectric property of bulk ferroelectrics under high DC bias at microwave frequencies

AbstractA microstrip‐based test fixture that can measure the paraelectric property of bulk ferroelectrics under high DC bias up to 2 kV at microwave frequencies is presented.In the measurement, a rectangular‐cuboid ferroelectrics with a pair of electrodes at opposite sides which represents a lumped capacitor is placed between a gap of a microstrip line. Blocking capacitors and a‐quarter‐wavelength stub lines are used to make sure that the vector network analyzer is double safe in the presence of high voltage. Thru‐reflect‐line calibration method is used to de‐embed the ferroelectric capacitor from blocking circuits and DC bias networks. The simulation and measurement results indicate that the method is suitable and safe for measuring the paraelectric property of bulk ferroelectrics at microwave frequencies under high DC bias. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1493–1496, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26844

The PreAmplifier ShAper for the ALICE TPC detector

In this paper the PreAmplifier ShAper (PASA) for the Time Projection Chamber (TPC) of the ALICE experiment at LHC is presented. The ALICE TPC PASA is an ASIC that integrates 16 identical channels, each consisting of Charge Sensitive Amplifiers (CSA) followed by a Pole-Zero network, self-adaptive bias network, two second-order bridged-T filters, two non-inverting level shifters and a start-up circuit. The circuit is optimized for a detector capacitance of 18–25pF. For an input capacitance of 25pF, the PASA features a conversion gain of 12.74mV/fC, a peaking time of 160ns, a FWHM of 190ns, a power consumption of 11.65mW/ch and an equivalent noise charge of 244e+17e/pF. The circuit recovers smoothly to the baseline in about 600ns. An integral non-linearity of 0.19% with an output swing of about 2.1V is also achieved. The total area of the chip is 18mm2 and is implemented in AMS's C35B3C1 0.35μm CMOS technology. Detailed characterization tests were performed on about 48000 PASA circuits before mounting them on the ALICE TPC front-end cards. After more than two years of operation of the ALICE TPC with p–p and Pb–Pb collisions, the PASA has demonstrated to fulfill all requirements.

Frequency-Reconfigurable Microstrip Antenna With Biasing Network Driven by a PIC Microcontroller

A low-profile microstrip patch antenna has been designed for tuning on a discrete set of instant frequencies. The frequency reconfigurability is obtained by resorting to electrically actuated switches operated via a software-controlled biasing network. A low-cost PIC microcontroller is employed to control the antenna operative condition among the available states. Measurements on a fabricated prototype show a good matching with simulations and prove the reliability of the proposed configuration.

CEO emotional bias and investment decision Bayesian Network method

This research examines the determinants of firms’ investment introducing a behavioral perspective that has received little attention in corporate finance literature. The following central hypothesis emerges from a set of recently developed theories: Investment decisions are influenced not only by their fundamentals but also depend on different factors. One factor is the biasness of any CEO to their investment, biasness depends on the cognition and emotions, because some leaders use them as heuristic for the investment decision instead of fundamentals. Keeping this in view, this paper shows how CEO emotional bias (optimism, loss aversion and overconfidence) effects the investment decisions. I will use Bayesian Network Method to examine this relation. Emotional bias has been measured by means of a questionnaire comprising several items. As for the selected sample, it has been composed of some100 Tunisian executives. Our results have revealed that the behavioral analysis of investment decision implies leader affected by behavioral biases (optimism, loss aversion, and overconfidence) adjusts its investment choices based on their ability to assess alternatives (optimism and overconfidence) and risk perception (loss aversion) to create of shareholder value and ensure its place at the head of the management team.

Dual-Band Frequency-Reconfigurable Folded Slot Antenna for Wireless Communications

This letter presents a novel frequency-reconfigurable folded slot antenna that could operate in two modes. Both modes have two resonant frequencies. The first mode resonant frequencies are at 3.4 and 5.27 GHz, and it can be used in WLAN band (5.15-5.35 GHz) and WiMAX band (3.40-3.69 GHz). The second mode operating frequencies are at 2.42 and 5.79 GHz, and they can be used in WLAN band (5.725-5.875 GHz) and Bluetooth band (2.40-2.484 GHz). The simulated results both for the return loss and peak gain agree with the measurements. Both the slot and arms of the proposed folded slot antenna are used to result in a resonant frequency, respectively. The advantage of this design is that the antenna is easy to fabricate, and this antenna could work without a complex bias network and a dc blocking capacitor.

ACTIVE UWB PRINTED ANTENNA WITH TUNABLE AND SWITCHABLE BAND-NOTCHED FUNCTIONS

A printed ultra-wideband (UWB) monopole antenna with both tunable and switchable band-notched characteristics is proposed. An embedded resonant slot loaded with a varactor and a pin diode controlled by DC signal through one common bias network is employed to tune and switch the notch band. In the \all-pass state when the two diodes are partially turned on, the power consumption of this active antenna is only 2.4W. Measured return loss, radiation pattern, gain and group delay of the introduced antenna are presented in this paper.

RF MEMS Switchable Slot Patch Antenna Integrated With Bias Network

The functionality of the patch antenna with switchable slot (PASS) is realized by integrating a commercially packaged MEMS (microelectromechanical system) switch and a novel bias network. The proposed antenna includes the fully integrated dc bias network capable of actuating the MEMS switch on the slot. The bias network can minimize the interference between dc bias and RF radiation mechanism with a negligible loss. By using a MEMS switch and the bias network, the patch antenna operates at 4.57 GHz and 4.88 GHz. The fabricated design shows acceptable return losses and directivities at the broadside direction when the switch is on and off. The influence of RF MEMS switch on the antenna impedance and radiation pattern is addressed.

Design and realization of 1.3 Gb/s off-chip transmission circuitry using 0.35 μm CMOS technology

Low-voltage-differential-signaling (LVDS) is one of the very popular technologies which simultaneously addresses low dynamic power consumption and high data rate transmission in modern high speed circuit applications. In this paper, system level integration design approach is applied to design LVDS transmitter featuring high off-chip data rate. Full wave electromagnetic simulation technique was adopted to accurately characterize possible couplings and parasitic effects induced from the off-chip components which then acted as the termination of the output circuitry. Common mode feedback was included to perform fine tuning on the offset leading to much higher overall precision. Meanwhile, generation of the controlled current and voltage across termination was guaranteed through the introduction of a constant transconductance bias network. The design was implemented using TSMC 3.3 V 0.35 μm CMOS technology with overall chip size of 0.923 mm2. At a DC power consumption level of 29.4 mW, the LVDS transmitter exhibited an off-chip data rate of 1.3 Gb/s validated through measurements.

Compact and Tunable Slot-Loop Antenna

A compact and tunable slot-loop antenna is studied in this communication. By periodically loading the slot line with varactor diodes, the slow-wave loop is capable of operating at frequencies from 2.34 GHz to 4 GHz with the measured input reflection coefficient better than -7.5 dB while occupying a small footprint of 0.072 λg × 0.072 λg (8.1 mm × 8.1 mm), where λg is the guided wavelength of a slot line at 2.34 GHz. The slot-loop in the ground plane is excited by a simple microstrip line, which enables the impedance matching from 3.2 GHz to 4 GHz for VSWR ≤ 2. A LC low-pass circuit is configured into the bias network to isolate the RF signal from the DC power path and consistent radiation patterns are experimentally obtained across the entire tunable frequencies of interest. The slot loop combined with the feed line and the bias circuitry is only 40 mm × 38.97 mm. Experimental results validate the feasibility of the presented antenna and agree well with simulation data.

Bias Stabilization of Negative Differential Conductance Oscillators Operated in Pulsed Mode

The paper reports on the bias stabilization of a 60-GHz resonant-tunneling diode (RTD)-based oscillator operated in pulsed mode. The oscillator contains an on-chip stabilizing capacitor, enabling the minimum dc consumption possible for such an RTD oscillator to be obtained, since all of the dc current is consumed by the active device. This is achieved without imposing restraints on the output power or introducing parasitic oscillations in the bias network. The oscillator that was constructed produces short 75-ps wavelets at 60 GHz, at an energy consumption of 1.3 pJ, during generation of a pulse. Experimental, simulated, and analytical results are presented for demonstrating how this mode of operation can be utilized in negative differential conductance oscillators.

Ka-Band 5-Bit MMIC Phase Shifter Using InGaAs PIN Switching Diodes

The design and performance of a Ka-band 5 b MMIC phase shifter using InGaAs PIN switching diodes is presented. In order to achieve low insertion loss and good phase shifting characteristics at Ka-band, a switched reactance type InGaAs PIN-diode phase shifter topology has been employed with a compact bias network. The fabricated InGaAs PIN MMIC phase shifter has demonstrated good performance characteristics such as a low insertion loss of less than 7.8 dB and a high P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> dB of 21.0 dBm compared to the previous results.