A 10-Gb/s Inductorless CMOS Analog Equalizer With an Interleaved Active Feedback Topology

A 10-Gb/s low-power analog equalizer for a 10-m coaxial cable has been realized in 0.13- $muhbox{m}$ CMOS technology. To compensate the cable loss of 20 dB at 5 GHz, this equalizer with an interleaved active feedback topology is proposed without using inductors. Moreover, additional capacitive and resistive source degenerations are incorporated to meet low-frequency losses. This circuit consumes only 14 mW (excluding the output buffer) from a 1.2-V supply with the output swing up to 400 $hbox{mV}_{rm pp}$, and it occupies $0.38 times 0.34 hbox{mm}^{2}$. For 8-, 9-, and 10-Gb/s pseudorandom binary sequences (PRBSs) of $2^{31} - 1$, the measured maximum peak-to-peak jitters are 26, 34, and 40 ps, respectively, and the measured bit error rate (BER) is less than $10^{-12}$.      

Fast Adaptive Polarization and PDL Tracking in a Real-Time FPGA-Based Coherent PolDM-QPSK Receiver

Fast polarization changes of 40 krad/s and 6-dB polarization-dependent loss (PDL) are tracked in a 2.8-Gb/s real-time coherent quadrature phase-shift keying receiver. The tolerance against fast polarization changes and PDL is measured for different polarization control time constants. The sensitivity penalty of the receiver at a polarization change speed of 40 krad/s is 0.7 dB at bit-error rate (BER) of $1times 10^{-3}$, with a BER floor of $6.1times 10^{-7}$. With an additional PDL of 6 dB, these figures become 1.7 dB and $9.6times 10^{-6}$, respectively.      

A Super-Tripling Technology Used in Radio-Over-Fiber Systems for Multiservice Wireless Signals Within a Millimeter-Wave Band

A super-tripling technology used in radio-over-fiber systems is presented in this letter for the optical generation and multiplexing of multiservice wireless signals within a millimeter-wave band. To realize the technology, optical carrier suppression is followed by optical single sideband with suppressed carrier modulation in the central station and optical stopband filtering in the base station is utilized. With the technology, 38.5-GHz amplitude shift keying and 41-GHz differential phase-shift keying signals both with 1.25-Gb/s data bit rate were demonstrated experimentally, and power penalties of about 1 dB at a bit-error rate of $10^{-8}$ were obtained after both signals transmitted over 10 km fiber. The spurious-free dynamic range of the link was measured to be 65 $hbox{dB}cdothbox{Hz}^{2/3}$ for the 38.5-GHz channel and 70 $hbox{dB}cdothbox{Hz}^{2/3}$ for the 41-GHz channel, both with the phase-noise at about ${-}$70 dBc/Hz.      

A Fully Integrated 0.13- $mu$m CMOS 40-Gb/s Serial Link Transceiver

A fully integrated 40-Gb/s transceiver fabricated in a 0.13-$mu$m CMOS technology is presented. The receiver operates at a 20-GHz clock performing half-rate clock and data recovery. Despite the low ${rm f}_{rm T}$ of 70 GHz, the input sampler achieves 10-mV sensitivity using pulsed latches and inductive-peaking techniques. In order to minimize the feedback latency in the bang-bang controlled CDR loop, the proportional control is directly applied to the VCO, bypassing the charge pump and the loop filter. In addition, the phase detection logic operates at 20 GHz, eliminating the need for the deserializers for the early/late timing signals. The four clock phases for the half-rate CDR are generated by a quadrature LC-VCO with microstrip resonators. A linear equalizer that tunes the resistive loading of an inductively-peaked CML buffer can improve the eye opening by 20% while operating at 39 Gb/s. The prototype transceiver occupies 3.4$, times ,$2.9 mm$^{2}$ with power dissipation of 3.6 W from a 1.45-V supply. With the equalizer on, the transmit jitter of the 39-Gb/s 2$^{15}-1$ PRBS data is 1.85 ${rm ps}_{rm rms}$ over a WB-PBGA package, an 8-mm PCB trace, an on-board 2.4-mm connector, and a 1 m-long 2.4-mm coaxial cable. The recovered divided-by-16 clock jitter is 1.77 ${rm ps}_{rm rms}$ and the measured BER of the transceiver is less than $10^{- 14}$ .      

Linear Systems, Sparse Solutions, and Sudoku

In this paper, we show that Sudoku puzzles can be formulated and solved as a sparse linear system of equations. We begin by showing that the Sudoku ruleset can be expressed as an underdetermined linear system: ${mmb{Ax}}={mmb b}$, where ${mmb A}$ is of size $mtimes n$ and $n>m$. We then prove that the Sudoku solution is the sparsest solution of ${mmb{Ax}}={mmb b}$, which can be obtained by $l_{0}$ norm minimization, i.e. $minlimits_{mmb x}Vert{mmb x}Vert_{0}$ s.t. ${mmb{Ax}}={mmb b}$. Instead of this minimization problem, inspired by the sparse representation literature, we solve the much simpler linear programming problem of minimizing the $l_{1}$ norm of ${mmb x}$, i.e. $minlimits_{mmb x}Vert{mmb x}Vert_{1}$ s.t. ${mmb{Ax}}={mmb b}$, and show numerically that this approach solves representative Sudoku puzzles.      

10-GHz and 20-GHz Channel Spacing High-Resolution AWGs on InP

This letter reports on 10-GHz and 20-GHz channel-spacing arrayed waveguide gratings (AWGs) based on InP technology. The dimensions of the AWGs are 6.8$,times,$8.2 mm$^{2}$ and 5.0$,times,$6.0 mm$^{2}$, respectively, and the devices show crosstalk levels of $-$12 dB for the 10-GHz and $-$17 dB for the 20-GHz AWG without any compensation for the phase errors in the arrayed waveguides. The root-mean-square phase errors for the center arrayed waveguides were characterized by using an optical vector network analyzer, and are 18 $^{circ}$ for the 10-GHz AWG and 28$^{circ}$ for the 10-GHz AWG.      

High Optical-Feedback Tolerance of Distributed Reflector Lasers With Wirelike Active Regions for Isolator-Free Operation

The optical-feedback tolerance of distributed reflector laser with a wirelike distributed feedback section and a distributed Bragg reflector section was investigated. A very high critical feedback level of ${-}$12.5 dB and low relative intensity noise were confirmed. Isolator-free 2.5-Gb/s to 10-km transmissions were demonstrated under ${-}$13.5-dB optical back-reflection with a power penalty of 2 dB.      

1580-V–40-$hbox{m}Omegacdot hbox{cm}^{2}$ Double-RESURF MOSFETs on 4H-SiC $(hbox{000}bar{hbox{1}})$

Double-reduced-surface-field (RESURF) MOSFETs with $hbox{N}_{2}hbox{O}$ -grown oxides have been fabricated on the 4H-SiC $(hbox{000} bar{hbox{1}})$ face. The double-RESURF structure is effective in reducing the drift resistance, as well as in increasing the breakdown voltage. In addition, by utilizing the 4H-SiC $(hbox{000}bar{hbox{1}})$ face, the channel mobility can be increased to over 30 $hbox{cm}^{2}/hbox{V}cdothbox{s}$, and hence, the channel resistance is decreased. As a result, the fabricated MOSFETs on 4H-SiC $( hbox{000}bar{hbox{1}})$ have demonstrated a high breakdown voltage $(V_{B})$ of 1580 V and a low on-resistance $(R_{rm ON})$ of 40 $hbox{m}Omega cdothbox{cm}^{2}$. The figure-of-merit $(V_{B}^{2}/R_{rm ON})$ of the fabricated device has reached 62 $hbox{MW/cm}^{2}$, which is the highest value among any lateral MOSFETs and is more than ten times higher than the “Si limit.”      

Q-Band pHEMT and mHEMT Subharmonic Gilbert Upconversion Mixers

This letter makes a comparison between Q-band 0.15 $mu{rm m}$ pseudomorphic high electron mobility transistor (pHEMT) and metamorphic high electron mobility transistor (mHEMT) stacked-LO subharmonic upconversion mixers in terms of gain, isolation and linearity. In general, a 0.15 $mu{rm m}$ mHEMT device has a higher transconductance and cutoff frequency than a 0.15 $mu{rm m}$ pHEMT does. Thus, the conversion gain of the mHEMT is higher than that of the pHEMT in the active Gilbert mixer design. The Q-band stacked-LO subharmonic upconversion mixers using the pHEMT and mHEMT technologies have conversion gain of $-$7.1 dB and $-$0.2 dB, respectively. The pHEMT upconversion mixer has an ${rm OIP}_{3}$ of $-$12 dBm and an ${rm OP}_{1 {rm dB}}$ of $-$24 dBm, while the mHEMT one shows a 4 dB improvement on linearity for the difference between the ${rm OIP}_{3}$ and ${rm OP}_{1 {rm dB}}$. Both the chip sizes are the same at 1.3 mm $times$ 0.9 mm.      

Performance Improvement of N-Type $hbox{TiO}_{x}$ Active-Channel TFTs Grown by Low-Temperature Plasma-Enhanced ALD

We report on performance improvement of $n$-type oxide–semiconductor thin-film transistors (TFTs) based on $hbox{TiO}_{x}$ active channels grown at 250 $^{circ}hbox{C}$ by plasma-enhanced atomic layer deposition. TFTs with as-grown $hbox{TiO}_{x}$ films exhibited the saturation mobility $(mu_{rm sat})$ as high as 3.2 $hbox{cm}^{2}/hbox{V}cdothbox{s}$ but suffered from the low on–off ratio $(I_{rm ON}/I_{rm OFF})$ of $hbox{2.0} times hbox{10}^{2}$. $hbox{N}_{2}hbox{O}$ plasma treatment was then attempted to improve $I_{rm ON}/I_{rm OFF}$. Upon treatment, the $hbox{TiO}_{x}$ TFTs exhibited $I_{rm ON}/I_{rm OFF}$ of $hbox{4.7} times hbox{10}^{5}$ and $mu_{rm sat}$ of 1.64 $hbox{cm}^{2}/hbox{V}cdothbox{s}$, showing a much improved performance balance and, thus, demonstrating their potentials for a wide variety of applications such as backplane technology in active-matrix displays and radio-frequency identification tags.      

2 MHz AO $Q$ -switched ${rm TEM}_{00}$ Grazing Incidence Laser With 3 at.% Neodymium Doped Nd:YVO$_{4}$

We present a detailed experimental and theoretical study of the ultrahigh repetition rate AO $Q$ -switched ${rm TEM}_{00}$ grazing incidence laser. Up to 2.1 MHz $Q$-switching with ${rm TEM}_{00}$ output of 8.6 W and 2.2 MHz $Q$ -switching with multimode output of 10 W were achieved by using an acousto-optics $Q$ -switched grazing-incidence laser with optimum grazing-incidence angle and cavity configuration. The crystal was 3 at.% neodymium doped Nd:YVO$_{4}$ slab. The pulse duration at 2 MHz repetition rate was about 31 ns. The instabilities of pulse energy at 2 MHz repetition rate were less than ${pm}6.7hbox{%}$ with ${rm TEM}_{00}$ operation and ${pm}3.3hbox{%}$ with multimode operation respectively. The modeling of high repetition rate $Q$-switched operation is presented based on the rate equation, and with the solution of the modeling, higher pump power, smaller section area of laser mode, and larger stimulated emission cross section of the gain medium are beneficial to the $Q$-switched operation with ultrahigh repetition rate, which is in consistent with the experimental results.      

Injection Locking and Switching Operations of a Novel Retro-Reflector-Cavity-Based Semiconductor Micro-Ring Laser

Injection locking and switching characteristics are investigated in the novel retro-reflector-cavitiy-based semiconductor ring laser with equivalent circular radius of 26 $mu$ m. The allowed detuning range is up to ${sim}$3 GHz wide and the highest side mode suppression ratio of ${sim}$ 43.7 dB can be achieved. A fast response speed of ${sim}$70 ps to the cavity is achieved, which indicates that this device can be utilized as an all optical switch at a data rate of 10 Gb/s or higher.      

Improved Microwave Noise Performance by SiN Passivation in AlGaN/GaN HEMTs on Si

Effects of silicon nitride (SiN) surface passivation by plasma enhanced chemical vapor deposition (PECVD) on microwave noise characteristics of AlGaN/GaN HEMTs on high-resistivity silicon (HR-Si) substrate have been investigated. About 25% improvement in the minimum noise figure $(NF_{min})$ (0.52 dB, from 2.03 dB to 1.51 dB) and 10% in the associate gain $(G_{rm a})$ (1.0 dB, from 10.3 dB to 11.3 dB) were observed after passivation. The equivalent circuit parameters and noise source parameters (including channel noise coefficient $(P)$, gate noise coefficient $(R)$, and their correlation coefficient $(C)$ ) were extracted. $P$ , $R$ and $C$ all increased after passivation and the increase of C contributes to the decrease of the noise figure. It was found that the improved microwave small signal and noise performance is mainly due to the increase of the intrinsic transconductance $(g_{{rm m}0})$ and the decrease of the extrinsic source resistance $(R_{rm s})$.      

Photosensitive Inverter and Ring Oscillator With Pseudodepletion Mode Load for LCD Applications

Photosensitive inverters and ring oscillators (ROs) with pseudodepletion mode loads (PDMLs) were integrated in LCD panels using conventional mass production processes. The delay time $(t_{rm pd})$ of five-stage ROs with PDML reduced from 204.3 $mu hbox{s}$ under dark to 16.3 $muhbox{s}$ under backlight illumination of 20 000 lx. The oscillation frequency exhibited a power-law dependence $(f_{rm osc} infty hbox{IL}^{gamma})$ on the backlight illuminance with the extracted fitting parameter $gamma = hbox{0.447}$ at room temperature.      

Positive Bias Temperature Instability (PBTI) Characteristics of Contact-Etch-Stop-Layer-Induced Local-Tensile-Strained $hbox{HfO}_{2}$ nMOSFET

The positive bias temperature instability (PBTI) characteristics of contact-etch-stop-layer (CESL)-strained $hbox{HfO}_{2}$ nMOSFET are thoroughly investigated. For the first time, the effects of CESL on an $hbox{HfO}_{2}$ dielectric are investigated for PBTI characteristics. A roughly 50% reduction of $V_{rm TH}$ shift can be achieved for the 300-nm CESL $hbox{HfO}_{2}$ nMOSFET after 1000-s PBTI stressing without obvious $ hbox{HfO}_{2}/hbox{Si}$ interface degradation, as demonstrated by the negligible charge pumping current increase ($≪$ 4%). In addition, the $hbox{HfO}_{2}$ film of CESL devices has a deeper trapping level (0.83 eV), indicating that most of the shallow traps (0.75 eV) in as-deposited $ hbox{HfO}_{2}$ film can be eliminated for CESL devices.      

VCSEL Module With Polymer Optical Output Rods to Enable High Efficiency Coupling for Optical Interconnection

New vertical-cavity surface-emitting laser (VCSEL) modules—designed with a optical output rod surrounded by cladding—have been proposed to realize high-efficiency low-cost optical interconnection. Prototypes have been fabricated using a photomask transfer method employing two kinds of ultraviolet curable resin. Observation of the near-field pattern and eye pattern for signal transmission shows that output rods with a diameter of 50- $mu$m efficiently confine the laser beam as an optical waveguide. In addition, ray tracing simulation indicates that this new VCSEL offers greater positional tolerance—as much as $+$18/ $-$22 $mu$m—for coupling to optical wiring in 90$^{circ}$ light path conversion.      

Schottky Barrier Height Modulation of Nickel–Dysprosium-Alloy Germanosilicide Contacts for Strained P-FinFETs

This letter reports on the fabrication and hole Schottky barrier $(Phi_{ rm B}^{rm p})$ modulation of a novel nickel (Ni)–dysprosium (Dy)-alloy germanosilicide (NiDySiGe) on silicon–germanium (SiGe). Aluminum (Al) implant is utilized to lower the $Phi_{rm B}^{rm p}$ of NiDySiGe from $sim$0.5 to $sim$ 0.12 eV, with a correspondingly increasing Al dose in the range of $ hbox{0}$–$hbox{2}timeshbox{10}^{15} hbox{atoms}/ hbox{cm}^{2}$. When integrated as the contact silicide in p-FinFETs (with SiGe source/drain), NiDySiGe with an Al implant dose of $hbox{2}timeshbox{10}^{14} hbox{atoms}/ hbox{cm}^{2}$ leads to 32% enhancement in $I_{rm DSAT}$ over p-FinFETs with conventional NiSiGe contacts. Ni–Dy-alloy silicide is a promising single silicide solution for series-resistance reduction in CMOS FinFETs.      

Integration and Characteristics of 40-Gb/s Electroabsorption Modulator Integrated Laser Module With a Driver Amplifier and Bias Tees

Integration of a 40-Gb/s electroabsorption modulator integrated distributed feedback (DFB) laser (EML) module with a driver amplifier and bias tee was investigated. For the EML fabrication the selective area growth (SAG) technique was adopted for the first time. It is shown that, with the SAG technique, the 3-dB bandwidth of about 45 GHz was measured in the electrical to optical response, and the return loss (S11) of below $-$10 dB was achieved for up to 50 GHz . To integrate a bias tee within the module, a right-angle bent coplanar waveguide (CPW) was developed. The right-angle bent CPW was characterized with S11 of below $-$ 10 dB for up to 35 GHz and insertion loss (S21) of about $-$1.4 dB for up to 40 GHz . The whole integrated module including the EML, a driver amplifier, and bias tee was characterized under the conditions of an operating temperature of 25 $^{circ}{rm C}$, the modulator bias of 1.4 V, and the DFB laser current of 40 mA. S11 of below $-$10 dB was obtained for up to 14 GHz and the measured electrical-to-optical response has 3-dB bandwidth of about 20 GHz.      

Impacts of $hbox{N}_{2}$ and $hbox{NH}_{3}$ Plasma Surface Treatments on High-Performance LTPS-TFT With High-$kappa$ Gate Dielectric

Low-temperature polycrystalline-silicon thin-film transistors (LTPS-TFTs) with high- $kappa$ gate dielectrics and plasma surface treatments are demonstrated for the first time. Significant field-effect mobility $mu_{rm FE}$ improvements of $sim$86.0% and 112.5% are observed for LTPS-TFTs with $hbox{HfO}_{2}$ gate dielectric after $hbox{N}_{2}$ and $ hbox{NH}_{3}$ plasma surface treatments, respectively. In addition, the $hbox{N}_{2}$ and $ hbox{NH}_{3}$ plasma surface treatments can also reduce surface roughness scattering to enhance the field-effect mobility $mu_{rm FE}$ at high gate bias voltage $V_{G}$, resulting in 217.0% and 219.6% improvements in driving current, respectively. As a result, high-performance LTPS-TFT with low threshold voltage $V_{rm TH} sim hbox{0.33} hbox{V}$, excellent subthreshold swing S.S. $sim$0.156 V/decade, and high field-effect mobility $mu_{rm FE} sim hbox{62.02} hbox{cm}^{2}/hbox{V} cdot hbox{s}$ would be suitable for the application of system-on-panel.      

Experimental 2.5-Gb/s QPSK WDM Phase-Modulated Radio-Over-Fiber Link With Digital Demodulation by a -Means Algorithm

Highest reported bit rate of 2.5 Gb/s for optically phase-modulated radio-over-fiber (RoF) link, employing digital coherent detection, is demonstrated. Demodulation of 3$,times,$ 2.5 Gb/s quadrature phase-shift-keying modulated wavelength-division-multiplexed RoF channels is achieved after 79 km of transmission through deployed fiber. Error-free performance (bit-error rate corresponding to $10^{{-}4}$) is achieved using a digital coherent receiver in combination with a $K$-means algorithm for radio-frequency phase recovery.