A Sub-0.2$^{circ}/$ hr Bias Drift Micromechanical Silicon Gyroscope With Automatic CMOS Mode-Matching

This paper describes a system architecture and CMOS implementation that leverages the inherently high mechanical quality factor (Q) of a MEMS gyroscope to improve performance. The proposed time domain scheme utilizes the often-ignored residual quadrature error in a gyroscope to achieve, and maintain, perfect mode-matching (i.e., $sim$0 Hz split between the high-Q drive and sense mode frequencies), as well as electronically control the sensor bandwidth. A CMOS IC and control algorithm have been interfaced with a 60 $mu{hbox {m}}$ thick silicon mode-matched tuning fork gyroscope $({rm M}^{2}mathchar"707B {rm TFG})$ to implement an angular rate sensing microsystem with a bias drift of 0.16$^{circ}/{hbox{hr}}$. The proposed technique allows microsystem reconfigurability—the sensor can be operated in a conventional low-pass mode for larger bandwidth, or in matched mode for low-noise. The maximum achieved sensor Q is 36,000 and the bandwidth of the microsensor can be varied between 1 to 10 Hz by electronic control of the mechanical frequencies. The maximum scale factor of the gyroscope is 88 ${hbox{mV}}/^{circ}/{hbox{s}}$ . The 3$~$ V IC is fabricated in a standard 0.6 $ mu{hbox {m}}$ CMOS process and consumes 6 mW of power with a die area of 2.25 ${hbox {mm}}^{2}$.      

Universal Lossless Compression of Erased Symbols

A source ${mmb X}$ goes through an erasure channel whose output is ${mmb Z}$. The goal is to compress losslessly ${mmb X}$ when the compressor knows ${mmb X}$ and ${mmb Z}$ and the decompressor knows ${mmb Z}$. We propose a universal algorithm based on context-tree weighting (CTW), parameterized by a memory-length parameter $ell$. We show that if the erasure channel is stationary and memoryless, and ${mmb X}$ is stationary and ergodic, then the proposed algorithm achieves a compression rate of $H(X_0vert X_{-ell}^{-1}, Z^ell)$ bits per erasure.      

Single-Exclusion Number and the Stopping Redundancy of MDS Codes

For a linear block code ${cal C}$, its stopping redundancy is defined as the smallest number of check nodes in a Tanner graph for ${cal C}$, such that there exist no stopping sets of size smaller than the minimum distance of ${cal C}{bf .},$ Schwartz and Vardy conjectured that the stopping redundancy of a maximum-distance separable (MDS) code should only depend on its length and minimum distance.      

Cyclic Codes and Sequences From Generalized Coulter–Matthews Function

In this paper, we will study the exponential sum $sum_{xin {BBF}_q}chi(alpha x^{(p^k+1)/2}+beta x)$ that is related to the generalized Coulter–Matthews function $x^{(p^k+1)/2}$ with $k/{rm gcd}(m,k)$ odd. As applications, we obtain the following: the correlation distribution of a $p$-ary $m$-sequence and a decimated $m$-sequence of degree ${p^k+1 over 2}$;      

Integrated Quadrature Couplers and Their Application in Image-Reject Receivers

Several fully-integrated multi-stage lumped-element quadrature hybrids that enhance bandwidth, amplitude and phase accuracies, and robustness are presented, and a fully-integrated double-quadrature heterodyne receiver front-end that uses two-stage Lange/Lange couplers is described. The Lange/Lange cascade exploits the inherent wide bandwidth characteristic of the Lange hybrid and enables a robust design using a relatively low transformer coupling coefficient. The measured image-rejection ratio is $>$ 55 dB over a 200 MHz bandwidth centered around 5.25 $~$GHz without any tuning, trimming, or calibration; the front-end features 23.5 dB gain, $-$79 dBm sensitivity, 5.6 dB SSB NF, $-$7$~$ dBm IIP3, $-$18 dB $S_{11}$ and a 1 mm $times$ 2 mm die area in 0.18$ mu{hbox {m}}$ CMOS.      

Properties and Applications of Preimage Distributions of Perfect Nonlinear Functions

The preimage distributions of perfect nonlinear functions from an Abelian group of order $n$ to an Abelian group of order $3$ or $4$, respectively, are studied. Based on the properties of the preimage distributions of perfect nonlinear functions from an Abelian group of order $3^{r}$ to an Abelian group of order $3$, the weight distributions of the ternary linear codes $C_{Pi}$ from the perfect nonlinear functions $Pi (x)$ from $F_{3^{r}}$ to itself are determined. These results suggest that two open problems, proposed by Carlet, Ding, and Yuan in 2005 and 2006, respectively, are answered.      

On the Values of Kloosterman Sums

Given a prime $p$ and a positive integer $n$ , we show that the shifted Kloosterman sums $$sum _{x in BBF _{p^{n}}} psi (x + ax^{p^{n}-2}) = sum _{xin BBF _{p^{n}}^{ast }} psi(x + ax^{-1}) + 1, quad a inBBF _{p^{n}}^{ast }$$ where $psi$ is a nontrivial additive character of a finite field $BBF _{p^{n}}$ of $p^{n}$ elements, do not vanish if $a$ belongs to a small subfield $BBF_{p^{m}} subseteq BBF _{p^{n}}$. This complements recent results of P. Charpin and G. Gong which in turn were motivated by some applications to bent functions.      

Analysis and Design of a CMOS UWB LNA With Dual- -Branch Wideband Input Matching Network

A wideband low-noise amplifier (LNA) based on the current-reused cascade configuration is proposed. The wideband input-impedance matching was achieved by taking advantage of the resistive shunt–shunt feedback in conjunction with a parallel LC load to make the input network equivalent to two parallel $RLC$-branches, i.e., a second-order wideband bandpass filter. Besides, both the inductive series- and shunt-peaking techniques are used for bandwidth extension. Theoretical analysis shows that both the frequency response of input matching and noise figure (NF) can be described by second-order functions with quality factors as parameters. The CMOS ultra-wideband LNA dissipates 10.34-mW power and achieves ${ S}_{11}$ below $-$8.6 dB, ${ S}_{22}$ below $-$10 dB, ${ S}_{12}$ below $-$26 dB, flat ${ S}_{21}$ of 12.26 $pm$ 0.63 dB, and flat NF of 4.24 $ pm$ 0.5 dB over the 3.1–10.6-GHz band of interest. Besides, good phase linearity property (group-delay variation is only $pm$22 ps across the whole band) is also achieved. The analytical, simulated, and measured results agree well with one another.      

Robust Precoder Adaptation for MIMO Links With Noisy Limited Feedback

In this paper, we propose two robust limited feedback designs for multiple-input multiple-output (MIMO) adaptation. The first scheme, namely, the combined design jointly optimizes the adaptation, CSIT (channel state information at the transmitter) feedback as well as index assignment strategies. The second scheme, namely, the decoupled design, focuses on the index assignment problem given an error-free limited feedback design. Simulation results show that the proposed framework has significant capacity gain compared to the naive design (designed assuming there is no feedback error). Furthermore, for large number of feedback bits $C_{rm fb}$, we show that under two-nearest constellation feedback channel assumption, the MIMO capacity loss (due to noisy feedback) of the proposed robust design scales like ${cal O}(P_e2^{-{{C_{rm fb}}over{t+1}}})$ for some positive integer $t$. Hence, the penalty due to noisy limited feedback in the proposed robust design approaches zero as $C_{rm fb}$ increases.      

Development of Optical MUX/DEMUX on Silicon Optical Bench—Assembly Accuracies

An optical subassembly of MUX/DEMUX where optical devices are hybrid-integrated on a silicon optical bench (SiOB) using a passive alignment method is reported. A tight tolerance of positional and tilting angular accuracy is required for optical devices attachment in order to maximize the coupling efficiency. The critical positioning transverse to the optical axis merely depends on the symmetry, and accuracy of the position and shape of trenches. Any inaccuracy primarily affects the noncritical positioning, i.e., $z$-axis and $theta{ z}$, in the direction along the optical axis; misalignment accumulated and causes undesired insertion loss. All the piece parts, i.e., mirror, thin-film filters (TFFs), ball lens, SiOB, etc., have a defined tolerance in their dimensions and surfaces which increases the challenge in achieving high placement accuracy along the optical axis. The effects from these inherent inaccuracies of the position and shape of trenches and piece parts could be minimized by optimizing the adhesive volume, improve the bottom flatness, proper procedure selection. Misalignment at each axis, e.g., x-, y-, z-, $theta{ x}$, $theta{ y}$, and $theta{ z}$ was characterized and its effect to the coupling efficiency was discussed.      

High-Temperature High-Power Operation of GaInNAs Laser Diodes in the 1220–1240-nm Wavelength Range

We report on the high-temperature performance of high-power GaInNAs broad area laser diodes with different waveguide designs emitting in the 1220–1240-nm wavelength range. Large optical cavity laser structures enable a maximum continuous-wave output power of $>$8.9 W at ${T}=20 ^{circ}$C with emission at 1220 nm and are characterized by low internal losses of 0.5 cm$^{-1}$ compared to 2.9 cm$^{-1}$ for the conventional waveguide structures. High-power operation up to temperatures of 120 $^{circ}$C is observed with output powers of $>$4 W at ${T}=90 ^{circ}$C. This laser diode showed characteristic temperatures of ${T}_{0} =112$ K and ${T}_{1}=378$ K.      

AlGaN/GaN HEMTs With Low Leakage Current and High On/Off Current Ratio

In this letter, we propose using an oxide-filled isolation structure followed by $hbox{N}_{2}/hbox{H}_{2}$ postgate annealing to reduce the leakage current in AlGaN/GaN HEMTs. An off-state drain leakage current that is smaller than $hbox{10}^{-9} hbox{A/mm}$ (minimum $hbox{5.1} times hbox{10}^{-10} hbox{A/mm}$) can be achieved, and a gate leakage current in the range of $hbox{7.8} times hbox{10}^{-10}$ to $hbox{9.2} times hbox{10}^{-11} hbox{A/mm}$ ($V_{rm GS}$ from $-$10 to 0 V and $V_{rm DS} = hbox{10} hbox{V}$) is obtained. The substantially reduced leakage current results in an excellent on/off current ratio that is up to $hbox{1.5} times hbox{10}^{8}$. An improved flicker noise characteristic is also observed in the oxide-filled devices compared with that in the traditional mesa-isolated GaN HEMTs.      

A 3-D High-Frequency Array Based 16 Channel Photoacoustic Microscopy System for In Vivo Micro-Vascular Imaging

This paper discusses the design of a novel photoacoustic microscopy imaging system with promise for studying the structure of tissue microvasculature for applications in visualizing angiogenesis. A new 16 channel analog and digital high-frequency array based photoacoustic microscopy system (PAM) was developed using an Nd:YLF pumped tunable dye laser, a 30 MHz piezo composite linear array transducer, and a custom multichannel receiver electronics system. Using offline delay and sum beamforming and beamsteering, phantom images were obtained from a 6 $mu{hbox {m}}$ carbon fiber in water at a depth of 8 mm. The measured $-6~{rm dB}$ lateral and axial spatial resolution of the system was $100pm 5~mu{hbox {m}}$ and $45pm 5~mu{hbox {m}}$, respectively. The dynamic focusing capability of the system was demonstrated by imaging a composite carbon fiber matrix through a 12.5 mm imaging depth. Next, 2-D in vivo images were formed of vessels around 100 $mu{hbox {m}}$ in diameter in the human hand. Three-dimensional in vivo images were also formed of micro-vessels 3 mm below the surface of the skin in two Sprague Dawley rats.      

Arsenic-Segregated Rare-Earth Silicide Junctions: Reduction of Schottky Barrier and Integration in Metallic n-MOSFETs on SOI

As an attempt to considerably reduce the equivalent contact resistivity of Schottky junctions, this letter studies the integration of rare-earth silicides, known to feature the lowest Schottky barriers (SBs) to electrons, coupled with a dopant segregation based on arsenic $(hbox{As}^{+})$ implantation. Both erbium (Er) and ytterbium (Yb) have been considered in the implant-before-silicide (IBS) and implant-to-silicide flavors. It is shown that the two schemes coupled with a limited thermal budget (500 $^{circ}hbox{C}$) produce an SB below the target of 0.1 eV. The implementation of IBS arsenic-segregated $hbox{YbSi}_{1.8}$ junctions in an n-type SB-MOSFET is demonstrated for the first time resulting in a current-drive improvement of more than one decade over the dopant-free counterpart.      

Extended Fault-Tolerant Cycle Embedding in Faulty Hypercubes

We consider fault-tolerant embedding, where an $n$-dimensional faulty hypercube, denoted by $Q_{n}$, acts as the host graph, and the longest fault-free cycle represents the guest graph. Let $F_{v}$ be a set of faulty nodes in $Q_{n}$. Also, let $F_{e}$ be a set of faulty edges in which at least one end-node of each edge is faulty, and let ${cal F}_{e}$ be a set of faulty edges in which the end-nodes of each edge are both fault-free. An edge in $Q_{n}$ is said to be critical if it is either fault-free or in $F_{e}$. In this paper, we prove that there exists a fault-free cycle of length at least $2^{n}-2vert F_{v}vert$ in $Q_{n} (ngeq 3)$ with $vert{cal F}_{e}vertleq 2n-5$, and $vert F_{v}vert+vert{cal F}_{e}vertleq 2n-4$ , in which each node is incident to at least two critical edges. Our result improves on the previously best known results reported in the literature, where only faulty nodes or faulty edges are considered.      

Integrated Hydrogen-Sensing Amplifier With GaAs Schottky-Type Diode and InGaP–GaAs Heterojunction Bipolar Transistor

New hydrogen-sensing amplifiers are fabricated by integrating a GaAs Schottky-type hydrogen sensor and an InGaP–GaAs heterojunction bipolar transistor. Sensing collector currents ( $I_{rm CN}$ and $I_{rm CH}$) reflecting to $hbox{N}_{2}$ and hydrogen-containing gases are employed as output signals in common-emitter characteristics. Gummel-plot sensing characteristics with testing gases as inputs show a high sensing-collector-current gain $(I_{rm CH}/I_{rm CN})$ of $≫hbox{3000}$. When operating in standby mode for in situ long-term detection, power consumption is smaller than 0.4 $muhbox{W}$. Furthermore, the room-temperature response time is 85 s for the integrated hydrogen-sensing amplifier fabricated with a bipolar-type structure.      

Logarithmic Sobolev Inequalities for Information Measures

For $alphageq 1$, the new Vajda-type information measure ${bf J}_{alpha}(X)$ is a quantity generalizing Fisher's information (FI), to which it is reduced for $alpha=2$ . In this paper, a corresponding generalized entropy power ${bf N}_{alpha}(X)$ is introduced, and the inequality ${bf N}_{alpha}(X) {bf J}_{alpha}(X)geq n$ is proved, which is reduced to the well-known inequality of Stam for $alpha=2$. The cases of equality are also determined. Furthermore, the Blachman–Stam inequality for the FI of convolutions is generalized for the Vajda information ${bf J}_{alpha}(X)$ and both families of results in the context of measure of information are discussed. That is, logarithmic Sobolev inequalities (LSIs) are written in terms of new more general entropy-type information measure, and therefore, new information inequalities are arisen. This generalization for special cases yields to the well known information measures and relative bounds.      

Free Space Optical System Performance for a Gaussian Beam Propagating Through Non-Kolmogorov Weak Turbulence

Atmospheric turbulence has been described for many years by Kolmogorov's power spectral density model because of its simplicity. Unfortunately several experiments have been reported recently that show Kolmogorov theory is sometimes incomplete to describe atmospheric statistics properly, in particular in portions of the troposphere and stratosphere. It is known that free space laser system performance is limited by atmospheric turbulence. In this paper we use a non-Kolmogorov power spectrum which uses a generalized exponent instead of constant standard exponent value 11/3 and a generalized amplitude factor instead of constant value 0.033. Using this spectrum in weak turbulence, we carry out, for a Gaussian beam propagating along a horizontal path, analysis of long term beam spread, scintillation, probability of fade, mean signal to noise ratio and mean bit error rate as variation of the spectrum exponent. Our theoretical results show that for alpha values lower than $alpha = {11/3}$, but not for alpha close to $alpha = 3$, there is a remarkable increase of scintillation and consequently a major penalty on the system performance. However when alpha assumes values close to $alpha = 3$ or for alpha values higher than $alpha = {11/3}$ scintillation decreases leading to an improvement on the system performance.      

Modeling of Distributed RLC Interconnect and Transmission Line via Closed Forms and Recursive Algorithms

This paper presents the closed forms of the state-space models and the recursive algorithms of the transfer function models for fast and accurate modeling of the distributed RLC interconnect and transmission lines, which may be evenly or unevenly distributed. Considered models include the distributed RLC interconnect lines with or without external source and load connection. The effective closed forms and recursive algorithms do not involve any matrix inverse, LU matrix factorization, or matrix multiplication, thus reducing the computation complexity dramatically. Especially, the computation complexity of the closed forms for any evenly or unevenly distributed RLC interconnect line circuits is only O(1) or $ { O}(m)$, respectively, in sense of the scalar multiplication times, where $ { m}ll{ N}$ of the system order. The features of new recursive algorithms are two recursive s-polynomials and the low computation complexity. Examples illustrate the new methods in both time and frequency domains. Comparing with the PSpice, the new methods can dramatically reduce the runtime of the time responses and the Bode plots by 25% – 98.5% in the examples. The results can be applied to the RLC interconnect analysis and model reduction as a key to new approach.      

A 5-GHz CMOS Type-II PLL With Low $K_{rm VCO}$ and Extended Fine-Tuning Range

A 5-GHz dual-path integer-$N$ Type-II phase-locked loop (PLL) uses an LC voltage-controlled oscillator and softly switched varactors in an overlapped digitally controlled integral path to allow a large fine-tuning range of approximately 160 MHz while realizing a low susceptibility to noise and spurs by using a low $K_{rm VCO}$ of 3.2 MHz/V. The reference spur level is less than $-$70 dBc with a 1-MHz reference frequency and a total loop-filter capacitance of 26 pF. The measured phase noise is $-$75 and $-$115 dBc/Hz at 10-kHz and 1-MHz offsets, respectively, using a loop bandwidth of approximately 30 kHz. This 0.25-${hbox{mm}}^{2}$ PLL is fabricated in a 90-nm digital CMOS process and consumes 11 mW from a 1.2-V supply.