Showing papers on "Switching time published in 2010"

A Fully Integrated 16-Element Phased-Array Transmitter in SiGe BiCMOS for 60-GHz Communications

Abstract: A phased-array transmitter (TX) for multi-Gb/s non-line-of-sight links in the four frequency channels of the IEEE 802.15.3c standard (58.32 to 64.8 GHz) is fully integrated in a 0.12-μm SiGe BiCMOS process. It consists of an up-conversion core followed by a 1:16 power distribution tree, 16 phase-shifting front-ends, and a digital control unit. The TX core is a two-step sliding-IF up-conversion chain with frequency synthesizer that features 40 dB of gain programmability, I/Q balance and LO leakage correction, and a modulator for 802.15.3c common-mode signaling. The tradeoffs involved in the implementation of a 1:16 power distribution network are analyzed and a hybrid passive/active distribution tree architecture is introduced. Each of the 16 front-ends consists of a balanced passive phase shifter and a variable-gain, 3-stage PA that features oP1dB programmability through the bias control of the its final stage. All of the chip features are digitally controllable and individual memory arrays are integrated at each front-end to enable fast beam steering through a high-speed parallel interface. The IC occupies 44 mm and is fully characterized on wafer. The TX delivers 9 to 13.5 dBm oPidB per element at 60.48 GHz with a total power consumption of 3.8 to 6.2 W. Each element attains a phase-shift range >360° with an amplitude variation <;±1 dB across phase settings and adjacent elements. Measurement results from a packaged IC in an antenna chamber are also presented including the demonstration of spatial power combining up to +40 dBm EIRP and 16-element radiation patterns.

An ultra-small, low power all-optical flip-flop memory on a silicon chip

Abstract: Ultra-small, low-power, all-optical switching and memory elements, such as all-optical flip-flops, as well as photonic integrated circuits of many such elements, are in great demand for all-optical signal buffering, switching and processing. Silicon-on-insulator is considered to be a promising platform to accommodate such photonic circuits in large-scale configurations. Through heterogeneous integration of InP membranes onto silicon-on-insulator, a single microdisk laser with a diameter of 7.5 µm, coupled to a silicon-on-insulator wire waveguide, is demonstrated here as an all-optical flip-flop working in a continuous-wave regime with an electrical power consumption of a few milliwatts, allowing switching in 60 ps with 1.8 fJ optical energy. The total power consumption and the device size are, to the best of our knowledge, the smallest reported to date at telecom wavelengths. This is also the only electrically pumped, all-optical flip-flop on silicon built upon complementary metal-oxide semiconductor technology. Scientists demonstrate that a single 7.5-μm-diameter microdisk laser coupled to a silicon-on-insulator wire waveguide can work as an all-optical flip-flop memory. Under a continuous bias of 3.5 mA, flip-flop operation is demonstrated using optical triggering pulses of 1.8 fJ and with a switching time of 60 ps. This device is attractive for on-chip all-optical signal buffering, switching, and processing.

Evidence and solution of over-RESET problem for HfO X based resistive memory with sub-ns switching speed and high endurance

Abstract: The memory performances of the HfO X based bipolar resistive memory, including switching speed and memory reliability, are greatly improved in this work. Record high switching speed down to 300 ps is achieved. The cycling test shed a clear light on the wearing behavior of resistance states, and the correlation between over-RESET phenomenon and the worn low resistance state in the devices is discussed. The modified bottom electrode is proposed for the memory device to maintain the memory window and to endure resistive switching up to 1010 cycles.

A 12b 22.5/45MS/s 3.0mW 0.059mm 2 CMOS SAR ADC achieving over 90dB SFDR

Abstract: CMOS technology scaling has opened a pathway to high-performance analog-to-digital conversion in the nanometer regime, where switching is preferred over amplifying. Successive-approximation-register (SAR) is one of the conversion architectures that rely on the high switching speed of process technology, and is thus distinctively known for its superior energy efficiency, small chip area, and good digital compatibility. When properly implemented, a SAR ADC also benefits from a potential rail-to-rail input swing, 100% capacitance utilization during input sampling (thus low kT/C noise), and insensitivity to comparator offsets during the conversion process. The linearity-limiting factors for SAR ADC are capacitor mismatch, sampling switch non-idealities, as well as the reference voltage settling issue due to the high internal switching speed of the DAC. In this work, a sub-radix-2 SAR ADC is presented, which employs a perturbation-based digital background calibration scheme and a dynamic-threshold-comparison (DTC) technique to overcome some of these performance-limiting factors.

Fast Transient Analysis of Next-Generation Interconnects Based on Carbon Nanotubes

Abstract: The scaling of copper wires and the increase in signal switching speed produce transient crosstalk coupling between interconnect lines, which causes overshoots and additional time delay The time-domain analysis of CMOS gates driving next-generation interconnects consisting of single wall carbon nanotube (SWCNT) bundles or multiwall carbon nanotubes (MWCNTs) is carried out Accurate simulation models of SWCNT bundles and MWCNTs are proposed in the frequency domain by using both the multiconductor transmission line (MTL) formulation and the multiequivalent single conductor (MESC) approach The fast transient voltage responses of two coupled nanointerconnects of 14 and 22 nm technologies to a pulsed input are computed by means of both the MTL and the MESC models The obtained results are in good agreement The same agreement is achieved by computing the 50% time delay of the output voltages

Limits on vanadium oxide Mott metal–insulator transition field-effect transistors

Abstract: There have been numerous proposals for use of metal–oxide materials as an alternative to semiconductors in field-effect transistors (FET), as current Si FET technology inevitably encounters intrinsic scaling limitations. We report on device-independent power–delay characteristics of potential VO2-based field induced Mott transistors and compare scaling limits to that of Si. Since the critical electric field for metal–insulator transition (MIT) in VO2 is similar to the breakdown field of Si, and due to the inherent possibility of further scaling along one direction in VO2, both materials exhibit similar lower bounds on switching energy. MIT in VO2 results in free carrier concentration several orders of magnitude larger than that of Si, easily overcoming the carrier transit time limits of conventional semiconductor MOSFETs. VO2 switching speed is constrained by the kinetics of the phase transition and more importantly limited thermal dissipation. Our simple model predicts an intrinsic VO2 material lower bound switching time of the order of 0.5 ps at a power transfer of 0.1 μ W .

Rate-Limiting Processes Determining the Switching Time in a Ag2S Atomic Switch

Abstract: The switching time of a Ag2S atomic switch, in which formation and annihilation of a Ag atomic bridge is controlled by a solid-electrochemical reaction in a nanogap between two electrodes, is investigated as a function of bias voltage and temperature. Increasing the bias voltage decreases the switching time exponentially, with a greater exponent for the lower range of bias than that for the higher range. Furthermore, the switching time shortens exponentially with raising temperature, following the Arrhenius relation with activation energy values of 0.58 and 1.32 eV for lower and higher bias ranges, respectively. These results indicate that there are two main processes which govern the rate of switching, first, the electrochemical reduction Ag+ + e−→Ag and, second, the diffusion of Ag+ ions. This investigation advances the fundamental understanding of the switching mechanism of the atomic switch, which is essential for its successful device application.

Submilliwatt, ultrafast and broadband electro-optic silicon switches

Abstract: We present a broadband 2x2 electro-optic silicon switch with an ultralow switching power and fast switching time based on a Mach-Zehnder interferometer (MZI). Forward-biased p-i-n junctions are employed to tune the phase of silicon waveguides in the MZI, to achieve a π-phase switching power of 0.6 mW with a drive voltage 0.83 V with a MZI arm length of 4 mm. The 10%-90% switching time is demonstrated to be 6 ns. Optical crosstalk levels lower than −17 dB are obtained for an optical bandwidth of 60 nm. The free carrier induced silicon refractive index change is extracted from the experimental results for the concentration range from 1016 to 1017 cm−3. We find that at the concentration of 1016 cm−3, the index change is about twice that calculated by the commonly used index change equation.

SPICE Macromodel of Spin-Torque-Transfer-Operated Magnetic Tunnel Junctions

Abstract: The electrical behavior of a magnetic tunnel junction (MTJ) using spin-torque-transfer (STT) switching was modeled using a SPICE subcircuit. The subcircuit is a two-terminal device that exhibits the electrical characteristics of an STT-MTJ. These characteristics include all the major transient characteristics of an MTJ, including the hysteresis, bias voltage dependence of the resistance, and the critical switching current versus the critical switching time. The model was designed to work over a wide range of operating conditions. Simulation and analysis of an MTJ-based D flip-flop are presented to demonstrate possible applications of the model.

A frequency-addressed plasmonic switch based on dual-frequency liquid crystals

Abstract: A frequency-addressed plasmonic switch was demonstrated by embedding a uniform gold nanodisk array into dual-frequency liquid crystals (DFLCs). The optical properties of the hybrid system were characterized by extinction spectra of localized surface plasmon resonances (LSPRs). The LSPR peak was tuned using a frequency-dependent electric field. A ∼4 nm blueshift was observed for frequencies below 15 kHz, and a 23 nm redshift was observed for frequencies above 15 kHz. The switching time for the system was ∼40 ms. This DFLC-based active plasmonic system demonstrates an excellent, reversible, frequency-dependent switching behavior and could be used in future integrated nanophotonic circuits.

High performance ultra-low energy RRAM with good retention and endurance

Abstract: High performance novel RRAM of 0.3 µW set power (0.1 µA at 3 V), 0.6 nW reset power (−0.3 nA at −1.8 V), fast 20 ns switching time, ultra-low 6 fJ switching energy, large 7×102 resistance window for 104 sec retention at 125°C, and 106 cycling endurance were measured simultaneously. This is the first time that the switching energy of new non-volatile memory is close to existing Flash Memory.

Thermally activated switching kinetics in second-order phase transition ferroelectrics

Abstract: The understanding of the electric polarization dynamics is critical for the operation of non-volatile memories based on ferroelectrics. In this paper we introduce a modified Kalmogorov-Avrami-Ishibashi polarization reversal model based on the non-equilibrium statistics of the of the domain nucleation process. The model yields the analytical expressions for the temporal dependence of the reversed polarization, transient switching current and the switching time, which can be used to explain a range of time and thermal dependent effects in ferroelectrics.

Control over multifunctionality in optoelectronic device based on organic phototransistor.

Abstract: Highly stable, reproducible, photosensitive organic field-effect transistors based on an n-type organic material, copper hexadecafluorophthalocyanine, and two different polymeric gate dielectrics has been reported and their performances have been compared by evaluating the surface/interface properties. The devices produced a maximum photocurrent gain (Ilight/Idark) of 79 at VG = 7 V and showed the potentiality as multifunctional optoelectronic switching applications depending upon the external pulses. The switching time of the transistor upon irradiation of light pulse, i.e., the photoswitching time of the device, was measured to be ∼10 ms. On the basis of optical or combination of optical and electrical pulses, the electronic/optoelectronic properties of the device can be tuned efficiently. The multifunctions achieved by the single device can ensure very promising material for high density RAM and other optoelectronic applications. Furthermore, as the device geometry in the present work is not limited to...

Experimental and theoretical investigation on polarization reversal in unfatigued lead-zirconate-titanate ceramic

Abstract: The dynamics of polarization switching in a soft lead-zirconate-titanate ceramic has been studied over a broad time window ranging from 10−6–106 for applied fields between 0.5 and 2.5 kV/mm. The classical Kolmogorov–Avrami–Ishibashi model of the polarization reversal was not able to satisfactory explain the obtained results. Therefore, a new concept for the polarization dynamics of ferroelectric ceramics has been suggested, which is based on two principal assumptions, (1) a strong dependence of the polarization switching time on the local electric field and (2) a random distribution of the local switching times caused by an intrinsic randomness in the field distribution within the system. Thereby the switching volume is composed as an ensemble of many regions with independent dynamics governed by local field exclusively. Such random field distribution could be well adjusted by a Gaussian distribution around the mean value of the field applied. A total polarization dependence on time and applied field was obtained in explicit form with only three fitting parameters which enabled a good description of the experimental results on polarization reversal in the whole time-field domain.

Enhanced ferroelectric switching characteristics of P(VDF-TrFE) for organic memory devices.

Abstract: In the following work, we report an approach to shorten the ferroelectric switching time of P(VDF-TrFE) film by blending with as-synthesized gold nanoparticles. Ferroelectric hysteresis measurements give remnant polarization and coercive field of 8 μC/cm2 and 50 MV/m, respectively. A series of electric pulses was applied for the characterization of ferroelectric polymers, and the switching time response was evaluated. More than 3 orders of magnitude reduction in switching time is observed for the polymer film blended with nanoparticles of the amount 1 × 10−6 wt %. The observed switching enhancements are discussed in terms of improved alignment of the ferroelectric crystal plane in the presence of the gold nanoparticles, whereby the aligned crystal planes experience a stronger effective field compared to the randomly oriented planes in pristine P(VDF-TrFE).

High Switching-Speed Operation of Optical Memory Based on Polarization Bistable Vertical-Cavity Surface-Emitting Laser

Abstract: Operation conditions of all-optical buffer memories based on polarization bistable vertical-cavity surface-emitting lasers (VCSELs) were investigated. The switching power dependence on the frequency detuning of the input optical signal was measured for a 980-nm polarization bistable VCSEL. The proper operating conditions for 10-Gb/s memory operation were also measured and found to be on the negative detuning side. Calculations based on a two-mode rate-equation model successfully explained the measured characteristics of the switching power dependence on the frequency detuning and the operating conditions. Maximum data rates for the memory operation strongly depended on the Q factor (i.e., photon lifetime) of the VCSELs. A possibility of 40-Gb/s memory operation using a polarization bistable VCSEL with a Q factor as low as 500 was shown.

Spin-transfer-torque resonant switching and injection locking in the presence of a weak external microwave field for spin valves with perpendicular materials

Abstract: The effects of a weak microwave field in the magnetization dynamics driven by spin-transfer-torque in spin valves with perpendicular materials have been systematically studied by means of full micromagnetic simulations. In the system we studied, depending on the working point (bias field and current) in the dynamical stability diagram, we observe either resonant switching or injection locking. The resonant switching, observed in the switching region, occurs when the field frequency is approaching the frequency of the main preswitching mode giving rise to an asymmetric power distribution of that mode in the sectional area of the free layer. At the resonant frequency, the switching time is weakly dependent on the relative phase between the instant when the current pulse is applied and the microwave field. The injection locking, observed in the dynamical region, is characterized by the following properties: (i) a locking bandwidth which is linearly dependent on the force locking and (ii) a locking for integer harmonics of the self-oscillation frequency. We compare our numerical results with analytical theory for nonautonomous nonlinear system obtaining a good agreement in the current region where the oscillation frequency and output power are characterized by a linear relationship.

Identification of the controlling parameter for the set-state resistance of a TiO2 resistive switching cell

Abstract: This study examined the parameter controlling the set-state resistance (Rset) of a Pt/TiO2/Pt resistive switching (RS) cell in unipolar RS mode. Although the compliance current in the current-voltage sweep had some effect on the Rset, the uncontrolled flow of charge from the parametric analyzer prevented making an accurate estimation of the parameters. The current transient in pulse switching observed using a high-speed digital oscilloscope and physical modeling showed that the capacitive charge moves vigorously at the moment of on-switching, and Rset is governed by the level of migrating charge. The actual switching time was ⪡50 ns.

Area-Efficient Fast-Speed Lateral IGBT With a 3-D n-Region-Controlled Anode

Abstract: A novel lateral insulated-gate bipolar transistor (LIGBT) structure on an silicon-on-insulator (SOI) substrate is proposed and discussed. The 3-D n-region-controlled anode concept makes this new structure effectively suppress the negative-differential-resistance (NDR) regime in conducting state, and what is more, during turn- off state, there are two effective paths for electron extraction, and the switching speed is very fast. As simulation results show, without sacrificing the high current-handling capability, the ratios of turn-off times for the proposed structure compared to that of the segment-anode-n-p-n-LIGBT presented earlier and the conventional LIGBT are 1 : 1.57 and 1 : 35.58, respectively. Due to the 3-D anode structure, the proposed device has efficient area usage and can be fabricated by the conventional SOI high-voltage IC process, so it is a promising device used in power ICs.

High frequency high efficiency bidirectional dc-dc converter module design for 10 kVA solid state transformer

Abstract: This paper presents the development of modular dual-half-bridge (MDHB) bidirectional dc-dc converter as the dc-dc stage of 10 kVA single phase solid state transformer (SST) for future renewable electric energy distribution and intelligent power management systems. The dc-dc converter, connected to 12 kV DC bus generated by an ac-dc rectifier interfacing with 7.2 kV electric utility grid, is to provide galvanic isolation function as well as 400 V DC bus for DC loads. The dc-dc converter consists of multiple low-voltage modules connected in input-series and output-parallel mode so that low-voltage commercial silicon MOSFETs, which usually have low conduction losses and high switching speed, can be adopted. Besides bidirectional power flow capability, the phase-shift dual-half-bridge (DHB) can realize zero-voltage-switching for all the switching devices without auxiliary switch devices, which enables the high switching frequency operation with low switching losses. As a result, high efficiency and high power density can be achieved. Other advantages of DHB topology have also been investigated for this application. A planar transformer adopting printed-circuit-board (PCB) winding is designed to realize high voltage solid isolation and identical parameters in multiple modules. The power loss of each main component has been analyzed for DHB converter under high frequency operation. Finally, the experimental results of two modules operating at 50 kHz switching frequency are presented with 97% efficiency.

Pulsed laser triggered high speed microfluidic switch and applications in fluorescent activated cell sorting

Abstract: In certain embodiments this invention provides a pulsed-laser triggered microfluidic switching mechanism that can achieve a switching time of 70 μs. This switching speed is two orders of magnitude shorter than that of the fastest switching mechanism utilized in previous μFACS.

A novel piloted fast switching multi poppet valve

Abstract: Switching and digital hydraulics require adequate switching valves for their practical application. A major criterion is the switching time which should in most cases be less than 5 ms. The demands on valve nominal flow rate are rather wide and range from less than 1 l/min (@ 5 bar) up to hundreds of litres. In this paper a new seat valve concept is presented. It is a piloted valve and employs a multi poppet concept. Its nominal flow rate is about 100 l/min and its switching time is about 1 ms for a pressure drop of 5 bar. With this valve energy efficient switching drives can be realized, for instance in the 10 kW to 20 kW range. Its seat type design makes the main stage a non leaking valve. Piloting is realized by a fast 3/2 solenoid actuated spool type switching valve with a nominal flow rate of 10 l/min @ 5 bar and a total switching time of about 2 ms. The paper presents the design of the poppet valve, simulation studies and experimental results concerning its static and dynamic characteristics.

Switching device driving unit and semiconductor apparatus

Abstract: PROBLEM TO BE SOLVED: To provide a switching device driving unit that, even in a case where a threshold voltage of a switching device is varied, can suppress variations in switching speed, and prevent a power loss caused by an unnecessary gate current in a constant ON operation state of the switching device, so that a desired slew rate can be easily set.SOLUTION: In switching device driving unit, a control current source circuit (21) sets to different values, based on a first input driving signal(UD), in a driving current to be source-outputted to a gate or a base of the switching device (11), a current (I1+I2) in a stage of an initial ON operation of a switching operation of the switching device and a current (I1) in a stage after completion of the switching operation.

Resistance switching of Cu/SiO2 memory cells studied under voltage and current-driven modes

Abstract: Resistance switching in Cu/SiO2-based conductive-bridging random access memories is studied under voltage and current-driven modes. These two modes are used to study memory cycling and time-dependent switching. Voltage-current (V-I) cycles (logarithmic current ramp) are compared to I-V cycles (linear voltage ramp). The Off-On transition in V-I cycles is governed by device capacitance. The Off-On switching time (in the 10−1–103 s range) was studied under constant voltage and constant current stresses. The switching time varies as exp(V0/V) and as 1/I. Switching kinetics is discussed considering a Fowler–Nordheim tunneling injection law and a field-induced nucleation theory.

Polarization behavior of poly(vinylidene fluoride-trifluoroethylene) copolymer ferroelectric thin film capacitors for nonvolatile memory application in flexible electronics

Abstract: The time domain and electric field dependence of the polarization switching kinetics of poly(vinylidene fluoride-trifluoroethylene) copolymer based thin film metal-ferroelectric-metal capacitors have been characterized. At room temperature, the time required for complete switching polarization decreases from >1 s to <50 μs as the voltage is increased from 6 to 12 V, while low nonswitching polarization is maintained. In the time domain, the ferroelectric switching polarization reversal behavior for devices biased above the coercive field follows the nucleation-limited-switching model. The exponential relationship between switching time and applied electric field indicates nucleation dominated switching kinetics. Switching behavior as a function of temperature was also characterized from −60 to 100 °C in the voltage range of 6–12 V. Higher temperatures induce larger dc conductance leakage at low frequencies and increases nonswitching polarization for all the voltages studied. It is demonstrated that for cer...

High-speed switching and filtering using PLZT waveguide devices

Abstract: Nano-second speed optical switches and filters fabricated in epitaxially grown (Pb, La)(Zr, La)O3 (PLZT) waveguides are reported. The optical switches including 1×2, 2×2, and 1×16 ports have switching time less than 10 ns and the AWG based 8×1 wavelength filter has 15 ns switching time. A PLZT buried waveguide is successfully developed to minimize insertion loss and polarization dependence in the optical switches.

All-optical wavelength-routing switch with monolithically integrated filter-free tunable wavelength converters and an AWG.

Abstract: We present a compact 4x8 wavelength-routing switch that monolithically integrates fast tunable wavelength converters (TWCs) and an arrayed-waveguide grating (AWG) for optical packet switching. The TWC consists of a double-ring-resonator-coupled tunable laser which allows rapid and stable switching, and an optical gate based on a parallel amplifier structure which prevents an input optical signal from being routed through the AWG (filter-free operation). A deep-ridge waveguide technology, employed for the AWG and ring resonators, facilitates the fabrication of the switch and makes the device compact. The filter-free TWCs achieve low crosstalk of the input optical signal of less than −22 dB. The wavelength routing operation of a non-return-to-zero (NRZ) signal at 10 Gbit/s is achieved with a switching time of less than 5 ns.

High-Reliability RF-MEMS Switched Capacitors With Digital and Analog Tuning Characteristics

Abstract: This paper presents an RF microelectromechanical system switched-capacitor suitable for tunable filters and reconfigurable networks. The switched-capacitor results in a digital capacitance ratio of 5 and an analog capacitance ratio of 5-9. The analog tuning of the down-state capacitance is enhanced by a positive vertical stress gradient in the the beam, making it ideal for applications that require precision tuning. A thick electroplated beam (4-4.5 μm) results in Q greater than 100 at C-X-band frequencies, switching times of 30-50 μs, and power handling of 0.6-1.1 W. The design also minimizes charging in the dielectric, resulting in excellent reliability performance even under hot-switched and high-power (1 W) conditions.