Effect of Ni on the Formation of ${hbox {Cu}}_{6}{hbox {Sn}}_{5}$ and ${hbox {Cu}}_{3}{hbox {Sn}}$ Intermetallics

In this paper, the effect of Ni on the formation of Cu₆Sn₅ and Cu₃Sn intermetallics between tin and (Cu,Ni) substrates has been studied by making use of the thermodynamic assessment of the Sn-Cu-Ni system. The driving forces for the diffusion of the elements in the intermetallic layers were calculated as a function of Ni content. Assuming constant mobilities of component atoms, the results suggest that the diffusion fluxes of all the components in the (Cu, Ni)₆Sn₅ layer increase with increasing content of dissolved Ni, while the Cu and Sn fluxes in the (Cu, Ni)₃Sn layer decrease. Therefore, the dissolution of Ni retards the growth of (Cu, Ni)₃Sn. When the Ni content of the (Cu,Ni) substrate is high enough, the intermetallic compound growth in the reaction zones is dominated by (Cu, Ni)₆Sn₅, and the (Cu, Ni)₃Sn layer disappears gradually. The small thickness of (Cu, Ni)₃Sn is associated with large difference between Sn and Cu fluxes in (Cu, Ni)₃Sn that encourages also the "Kirk-endall void" formation. In addition, the calculated driving forces suggest that the growth rate of (Cu, Ni)₆Sn₅ should further increase if (Cu, Ni)₃Sn disappears, resulting in an unusually thick (Cu, Ni)₆Sn₅ layer. The results of thermodynamic calculations supplemented with diffusion kinetic considerations are in good agreements with recent experimental observations.     

Temperature Dependence of Optical Gain and Loss in $lambda approx$ 8.2–10.2 $mu$m Quantum-Cascade Lasers

Temperature-dependent optical gain and waveguide loss have been measured for continuous-wave operated quantum-cascade lasers with wavelengths between 8.2 and 10.2 mum up to room temperature using the Hakki-Paoli method. The gain coefficient decreases with increasing temperature, and is close to the designed value for vertical transition lasers, but smaller than the designed value for diagonal transition lasers. The waveguide loss, however, is two to three times higher than calculated from free carrier absorption, and can be nearly constant, increase or decrease with temperature depending on sample design, which indicates that it is dominated by another mechanism other than plain free carrier absorption. One likely factor resulting in high waveguide loss is intersubband resonant absorption into higher lying states.     

Actively $Q$ -switched and Mode-Locked Diode-Pumped ${hbox {Nd:GdVO}}_{4}{hbox {--KTP}}$ Laser

By using a comparative simple configuration and a short cavity length, a diode-pumped actively Q -switched and mode-locked intracavity frequency doubled Nd:GdVO₄-KTP green laser with the modulation depth 100% was realized, from which the great average output power, the high efficiency were obtained and the mode-locked pulse inside the Q -switched pulse has a repetition rate of 476 MHz. Using the hyperbolic secant function methods and by considering the Gaussian distribution of the intracavity photon density, the influences of continuous pump rate, the upper state lifetime of the active medium and the turnoff time of the acousto-optic Q -switch, we proposed a developed rate equation model for actively Q -switched and mode-locked green lasers. With this developed model, the theoretical calculations are in good agreement with the experimental results and the width of the mode-locked green pulse is estimated to be about 185 ps.     

A Single-Chip UHF RFID Reader in 0.18 $mu{hbox {m}}$ CMOS Process

A single-chip UHF RFID reader that integrates all building blocks—including an RF transceiver, IQ data converters, and a digital baseband—is implemented in a 0.18 $mu{hbox {m}}$ CMOS process. A high-linearity RX front-end and a low-phase-noise synthesizer are proposed to handle the large self-interferer, which is a key challenge in the reader RX design. Highly reconfigurable mixed-signal baseband architecture for channel-selection filtering is proposed to achieve power optimization for multi-protocol operation with different system dynamic ranges and data rates. The reader dissipates a maximum power of 276.4 mW when transmitting maximum output power of 10.4 dBm and receiving the tag's response of $-$70 dBm in the presence of $-$5 dBm self-interferer while occupying 18.3 ${hbox {mm}}^{2}$.      

Numerical Modeling of Diode-End-Pumped High-Power ${hbox {Er}}^{3+}$:YAG Lasers

A theoretical model is presented describing continuous-wave operation of diode-end-pumped Er³⁺ :YAG lasers. Implemented as a numerical computer model it takes into account the full spectral information of the pump and laser transitions as well as all important ionic levels, their Stark splitting, decay schemes, up-conversion processes, excited-state absorption and especially the thermal dependencies of these important parameters. The model is compared to experimental results with good agreement and predicts highly efficient operation of Er:YAG lasers even at high temperatures.     

New Terahertz Laser Lines From $^{13}{hbox {CD}}_{3}{hbox {OH}}$ Pumped by Regular and Hot Bands ${hbox {CO}}_{2}$ Laser

We have used our new pulsed ${hbox {CO}}_{2}$ laser, operating both on regular and hot bands, to excite the $^{13}{hbox {CD}}_{3}{hbox {OH}}$ methanol isotopomer. This has lead to the observation of 13 new high-threshold far-infrared laser emissions (also identified as terahertz laser lines), with frequencies in the range between 24.11 and 102.56 cm$^{-1}$ (0.72–3.07 THz). The absorption transitions leading to these new FIR laser emissions have been located by observing the optoacoustic absorption spectra around the ${hbox {CO}}_{2}$ emissions. Here, we present these new far-infrared laser lines, characterized in wavelength, polarization, offset relative to the center of the pumping ${hbox {CO}}_{2}$ laser transition, relative intensity, and optimum operation pressure.      

Design of Photonic Crystal Nanocavity With $Q$-Factor of ${{sim}10^{9}}$

Photonic crystal nanocavities are expected to make great contributions in areas of physics and engineering such as the slowing and stopping of light and optical quantum information processing. We first review approaches to the goal of increasing the quality factor of two-dimensional photonic crystal nanocavities. Losses from a cavity can be suppressed, with a consequent increase of the quality factor, by containing the electromagnetic field in the form of a Gaussian envelope function. We then propose a new method of analytical cavity design, based on the detailed investigation of waveguide modes, in order to realize Gaussian cavity mode fields. This has enabled us to achieve a quality factor of while maintaining a cavity volume of one cubic wavelength.     

A 40-MHz Double Differential-Pair CMOS OTA With $-{hbox{60-dB}}$ IM3

A configuration of a linearized operational transconductance amplifier (OTA) for low-voltage and high-frequency applications is proposed. By using double pseudodifferential pairs and the source-degeneration structure under nano-scale CMOS technology, the nonlinearity caused by short channel effect from a small feature size can be minimized. A robust common-mode control system is designed for input and output common-mode stability and thus reduces distortion caused b y common-mode voltage variation. Tuning ability can be achieved by using MOS transistors in the linear region. The linearity of the OTA is about -60-dB third-order inter-modulation (IM3) distortion for up to 0.9 V_pp at 40 MHz. This OTA was fabricated by the TSMC 180-nm deep n-well CMOS process. It occupies a small area of 15.1times10^-3 mm² and the power consumption is 9.5 mW under a 1.5-V supply voltage.     

A Tunable Pseudo-Differential OTA With $-78~{hbox {dB}}$ THD Consuming 1.25 mW

A novel linear tunable transconductor based on a combination of linearization techniques is presented. The input signal is transferred to the V-I conversion element by means of a high-speed feedback loop. Then, the linear V-I conversion is accomplished using quasi-floating-gate MOS transistors biased in the triode region. Finally, the absence of current mirrors in the signal path provides low sensitivity to transistor mismatch and reduces the harmonic distortion. The operational transconductance amplifier (OTA) was fabricated in a 0.5-mum CMOS technology with a single 3.3-V supply voltage. Experimental results show a total harmonic distortion of -78 dB at 1 MHz with 1-V_pp input signal. High linearity of the OTA is obtained over a two octave tuning range with only 1.25-mW power consumption.     

Reliability of Combined $k{hbox{-out-of-}}n$ and Consecutive $k_{c}{hbox{-out-of-}}n$ Systems of Markov Dependent Components

A combined $k{hbox{-out-of-}}n$ :$F(G)$ & consecutive $k_{c}{hbox{-out-of-}}n{hbox{:}}F(G)$ system fails (functions) iff at least $k$ components fail (function), or at least $k_{c}$ consecutive components fail (function). These models involve two common failure criteria, and can be used in various situations depending on the actual failure criteria involving consecutive components, or all components. Explicit formulas for the reliabilities of these systems are obtained for Markov dependent components using the distribution theory of runs. Some numerical results are also presented.      

A 3$,times,$5-Gb/s Multilane Low-Power 0.18-$mu{hbox {m}}$ CMOS Pseudorandom Bit Sequence Generator

A low-power, three-lane, pseudorandom bit sequence (PRBS) generator has been fabricated in a 0.18-mum CMOS process to test a multilane multi-Gb/s transmitter that cancels far-end crosstalk. Although the proposed PRBS generator was designed to produce three uncorrelated 12-Gb/s PRBS sequences, measurement results included in this paper have been obtained at only 5 Gb/s due to test setup limitations. The prototype employs a CMOS latch optimized to operate at frequencies close to the of the process and a current-mode logic (CML) MUX with modified active inductor loads for better high-speed large-signal behavior. In order to reduce the power consumption, a quarter-clock rate linear feedback shift register (LFSR) core in a power-efficient parallel architecture has been implemented to minimize the use of power-hungry, high-speed circuitry. Further power reduction has been achieved through the clever partitioning of the system into static logic and CML. In addition, the prototype design produces three uncorrelated 12-Gb/s data streams from a single quarter-rate LFSR core, thereby amortizing the power across multiple channels which lowers the power per channel by 3 times. The total measured power consumption at 5 Gb/s is 131 mW per lane and the calculated figure of merit per lane is 0.84 pJ/bit, which is significantly better than previously published designs.     

300-mm Low-${hbox {k}}$ Wafer Dicing Saw Development

With the further shrinking of IC dimensions, low- material has been widely used to replace the traditional SiO interlayer dielectric (ILD) in order to reduce the interconnect delay. The introduction of low- material into silicon imposed challenges on dicing saw process. ILD and metal layers peeling and its penetration into the sealing ring of the die during dicing saw are the most common defects. In this paper, the low- material structure and its impact on wafer dicing were elaborated. A practical dicing quality inspection matrix was developed to assess the cutting process variation. A 300-mm CMOS90-nm dual damascene low- wafer was chosen as a test vehicle to develop a robust low- dicing saw process. The critical factors (dicing blade, index speed, spindle speed, cut in depth, test pattern in the saw street, etc.) affecting cutting quality were studied and optimized. The selected C90 Dual damascene low- device passed package reliability tests with the optimized low- dicing saw recipe and process. The further improvement and solutions in eliminating the low- dicing saw peeling were also explored.     

InGaAs/GaAs 0.98- $mu{hbox {m}}$ Low-Divergence Central-Lobe Semiconductor Lasers With $delta$ -Doped Resonant Tunneling Quantum Wells

In this paper, we describe a new structure design for producing low-threshold, high-efficiency, and high-brightness 0.98-$mu{hbox {m}}$ lasers. In this structure, we incorporated a self-discriminating weak optical confinement asymmetrical waveguide coupled to passive waveguides, and an active region based on three InGaAs quantum wells (QWs) coupled to Te n-type $delta$-doping. Optimized coupling between the $delta$-doping and the three QWs, together with waveguide optimization and doping profile optimization, yields $J_{rm th}=98 {hbox {A/cm}}^{2}$ per QW, ${T}_{0}=80;^{circ}hbox{C}$, and a far-field central lobe angle of $sim 10^{circ}$.      

Temperature Effect on $Ku$-Band Current-Reused Common-Gate LNA in 0.13-$mu{hbox{m}}$ CMOS Technology

This paper presents the temperature effect on a Ku-band NMOS common-gate low-noise amplifier (CG-LNA). The temperature characteristics of an NMOS transistor and spiral inductors are obtained over the temperature range from 253 to 393 K. These results show that the optimal bias condition minimizes the transconductance and drain current temperature variations. Based on these results, a current-reused CG-LNA with good temperature performance is designed. At ambient temperatures, the CG-LNA has a measured power gain of 10.3 dB and a noise figure (NF) of 4.3 dB at 15.2 GHz, while consuming 4.5 mA from a 1.3-V power supply. When the temperature varies from 253 to 393 K, the CG-LNA has a power gain variation of 3 dB, NF variation of 2 dB , and dc power consumption variation of 11.9%. This paper is the first to report the temperature effect on Ku-band CG-LNAs.     

Underdetermined Anechoic Blind Source Separation via $ell^{q}$-Basis-Pursuit With $q≪1$

In this paper, we address the problem of underdetermined blind source separation (BSS) of anechoic speech mixtures. We propose a demixing algorithm that exploits the sparsity of certain time-frequency expansions of speech signals. Our algorithm merges lscr^q -basis-pursuit with ideas based on the degenerate unmixing estimation technique (DUET) [Yiotalmaz and Rickard, "Blind Source Separation of Speech Mixtures via Time-Frequency Masking," IEEE Transactions on Signal Processing, vol. 52, no. 7, pp. 1830-1847, July 2004]. There are two main novel components to our approach: 1, our algorithm makes use of all available mixtures in the anechoic scenario where both attenuations and arrival delays between sensors are considered, without imposing any structure on the microphone positions, and 2, we illustrate experimentally that the separation performance is improved when one uses lscr^q-basis-pursuit with q < 1 compared to the q = 1 case. Moreover, we provide a probabilistic interpretation of the proposed algorithm that explains why a choice of 0.1 les q les 0.4 is appropriate in the case of speech. Experimental results on both simulated and real data demonstrate significant gains in separation performance when compared to other state-of-the-art BSS algorithms reported in the literature.     

22.7-dB Gain $-$19.7-dBm $ICP_{1{rm dB}}$ UWB CMOS LNA

A fully differential CMOS ultrawideband low-noise amplifier (LNA) is presented. The LNA has been realized in a standard 90-nm CMOS technology and consists of a common-gate stage and two subsequent common-source stages. The common-gate input stage realizes a wideband input impedance matching to the source impedance of the receiver (i.e., the antenna), whereas the two subsequent common-source stages provide a wideband gain by exploiting RLC tanks. The measurements have exhibited a transducer gain of 22.7 dB at 5.2 GHz, a 4.9-GHz-wide B _3dB, an input reflection coefficient lower than -10.5 dB, and an input-referred 1-dB compression point of -19.7 dBm, which are in excellent agreement with the postlayout simulation results, confirming the approach validity and the design robustness.     

Matrix Methods for the Dynamic Range Optimization of Continuous-Time $G_{m}$- $C$ Filters

This paper presents a synthesis procedure for the optimization of the dynamic range of continuous-time fully differential $G_{m}$-$C$ filters. Such procedure builds up on a general extended state-space system representation which provides simple matrix algebra mechanisms to evaluate the noise and distortion performances of filters, as well as, the effect of amplitude and impedance scaling operations. Using these methods, an analytical technique for the dynamic range optimization of weakly nonlinear $G_{m}$- $C$ filters under power dissipation constraints is presented. The procedure is first explained for general filter structures and then illustrated with a simple biquadratic section.      

High-Performance $hbox{In}_{0.7}hbox{Ga}_{0.3}hbox{As}$ -Channel MOSFETs With High-$kappa$ Gate Dielectrics and $alpha$-Si Passivation

Long and short buried-channel $hbox{In}_{0.7}hbox{Ga}_{0.3}hbox{As}$ MOSFETs with and without $alpha$-Si passivation are demonstrated. Devices with $alpha$-Si passivation show much higher transconductance and an effective peak mobility of 3810 $hbox{cm}^{2}/ hbox{V} cdot hbox{s}$. Short-channel MOSFETs with a gate length of 160 nm display a current of 825 $muhbox{A}/muhbox{m}$ at $V_{g} - V_{t} = hbox{1.6} hbox{V}$ and peak transconductance of 715 $muhbox{S}/muhbox{m}$. In addition, the virtual source velocity extracted from the short-channel devices is 1.4–1.7 times higher than that of Si MOSFETs. These results indicate that the high-performance $hbox{In}_{0.7}hbox{Ga}_{0.3} hbox{As}$-channel MOSFETs passivated by an $alpha$ -Si layer are promising candidates for advanced post-Si CMOS applications.      

Spectroscopy and Lasing of Yb-Doped ${hbox {NaY}}{({hbox {WO}}_{4})}_{2}$: Tunable and Femtosecond Mode-Locked Laser Operation

Tetragonal (space group f4 macr) single crystals of NaY(WO₄)₂ doped with Yb to a density of 4.52 times 10²⁰ cm^-3 have been employed as laser active materials for the 1-mum spectral range, operating at room temperature. Using Ti:sapphire laser pumping, slope efficiencies as high as 74.6% were achieved without special cooling for the pi-polarization. The Yb-laser was continuously tunable from 1003.7 to 1073.0 nm with a birefringent filter. Pulses as short as 53 fs were obtained at 1035 nm by SESAM passive mode-locking with intracavity dispersion compensation and additional extracavity pulse compression using analogous prism pairs. Experimental data on the spectroscopic properties of Yb³⁺ in the 5-300 K temperature range and the room temperature optical properties of this novel Yb-host is also presented.