Theoretical and experimental study of 10 Gb/s transmissionperformance using 1.55 μm LiNbO3-based transmitters withadjustable extinction ratio and chirp

This paper has experimentally and theoretically investigated transmission performance depending on chirping and extinction ratio for a 10 Gb/s transmission system with the standard single-mode fiber. The transmission performance can be dramatically degraded or improved by adjusting chirp and extinction ratio in a 1.55 μm LiNbO₃ modulator-based transmitter and erbium-doped fiber amplifier (EDFA)-pin diode receiver configuration. To estimate the transmission performance, bit error rate (BER) characteristics rather than eye-opening penalty (EOP) have been calculated by solving the nonlinear Schrodinger equation with including the model of chirping and extinction ratio for the transmitter, and noise and intersymbol interference for the receiver. This simulation can predict the measured BER characteristics well enough to see interplaying between chirping and extinction ratio     

A Pragmatic Design for 3GPP/WLAN RAN Level Interworking

Wireless Personal Communications - As mobile data traffic continues to grow significantly, traffic offloading is an important issue. Since WiFi-capable user equipments (UEs) are very popular...     

A 1-17-GHz InGaP-GaAs HBT MMIC analog multiplier and mixer with broad-band input-matching networks

An InGaP-GaAs heterojunction bipolar transistor (HBT) analog multiplier/mixer monolithic microwave integrated circuit (MMIC) is developed that adopts a Gilbert-cell multiplier with broad-band input-matching networks to widen the bandwidth up to 17 GHz. This MMIC was fabricated using a commercially available 6-in InGaP-GaAs HBT MMIC process. It achieved a measured sensitivity of above 1100 V/W for an analog multiplier and a conversion gain of better than 9 dB for a mixer. It also demonstrated a lower corner frequency and noise than that of an InP HBT analog multiplier. The measured low-frequency noise was 10 nV/sqrt(Hz), which is about half of that of an InP HBT analog multiplier with a similar architecture. The corner frequency of the low-frequency noise was roughly estimated to be 15 kHz. The measured performance of this MMIC chip with gain-bandwidth-product (GBP) of 47 GHz rivals that of the reported GaAs-based analog multipliers and mixers. The high GBP result achieved by this chip is attributed to the HBT device performance and the broad-band input-matching network.     

An experimental test of a theory of lightning-induced voltages onan overhead wire

Measured and calculated voltages induced on an unenergized overhead power line by lightning return strokes at distances greater than 5 km from the line are presented. The experiment was performed at the NASA Kennedy Space Center during the summer of 1985 and involved the simultaneous measurement of the voltage induced at one end of the top phase of a three-phase power line and the two horizontal components of the return-stroke magnetic field incident on the line. The effective ground conductivity was determined from previous simultaneous measurements of the vertical and horizontal electric fields. Experiments were performed for two cases: (1) all phases of the power line open-circuited, and (2) one end of the top line terminated at 600 Ω with the other end open-circuited and the other two phases open-circuited at both ends. The waveshapes of the measured and calculated voltages are in reasonably good agreement, and the reasons for observed discrepancies are discussed     

Diagnostic Data Compression Techniques for Embedded Memories with Built-In Self-Test

A system-on-chip (SOC) usually consists of many memory cores with different sizes and functionality, and they typically represent a significant portion of the SOC and therefore dominate its yield. Diagnostics for yield enhancement of the memory cores thus is a very important issue. In this paper we present two data compression techniques that can be used to speed up the transmission of diagnostic data from the embedded RAM built-in self-test (BIST) circuit that has diagnostic support to the external tester. The proposed syndrome-accumulation approach compresses the faulty-cell address and March syndrome to about 28% of the original size on average under the March-17N diagnostic test algorithm. The key component of the compressor is a novel syndrome-accumulation circuit, which can be realized by a content-addressable memory. Experimental results show that the area overhead is about 0.9% for a 1Mb SRAM with 164 faults. A tree-based compression technique for word-oriented memories is also presented. By using a simplified Huffman coding scheme and partitioning each 256-bit Hamming syndrome into fixed-size symbols, the average compression ratio (size of original data to that of compressed data) is about 10, assuming 16-bit symbols. Also, the additional hardware to implement the tree-based compressor is very small. The proposed compression techniques effectively reduce the memory diagnosis time as well as the tester storage requirement.     

2.488 Gb/s-318 km repeaterless transmission using erbium-dopedfiber amplifiers in a direct-detection system

The authors have achieved a 2.488 Gb/s, 318 km repeaterless transmission without any fiber dispersion penalty through a nondispersion-shifted fiber in a direct detection system. The system was loss limited with a T-R power budget of 57 dB. Three key components enabled the authors to achieve this result: (1) a Ti:LiNbO₃ external amplitude modulator enabling a dispersion-free transmission, (2) erbium-doped fiber amplifiers increasing the transmitting power to +16 dBm, and (3) an erbium-doped fiber preamplifier enabling a high-receiver sensitivity of -4.1 dBm for 10^-9 BER. To the author's knowledge, this result is the longest repeaterless transmission span length ever reported for direct detection at this bit rate. From the experimental results and a theoretical model, the authors identified the sources of the receiver sensitivity degradation from the quantum limit (-48.6 dBm) and estimated the practically achievable receiver sensitivity of ~-44 dBm (~-124 photons/bit) for 2.5 Gb/s optical preamplifier detection     

Performance evaluation of waveguide phase modulators for coherent systems at 1.3 and 1.5 µm

This article describes the fabrication and performance evaluation ofX-cut andZ-cut Ti:LiNbO3traveling wave waveguide phase modulators designed for coherent systems applications at 1.3 and 1.5 μm. Details of device fabrication and measurements of phase shift as a function of optical wavelength, input polarization, modulation voltage, and modulation frequency are reported. Phase modulator performance in a 40-Mbit/s self-heterodyne coherent DPSK experiment is also discussed.     

The barrier height change and current transport phenomena with the presence of interfacial layer in MIS Schottky barrier solar cells

In this comprehensive study, several interesting results which are different from those previous are reported. We find the barrier height decreases for n-type and increases for p-type when positive ions are introduced into the insulating layer. The increase of open circuit voltage can be traced to the suppression of the dark saturation current by the depletion field induced by the positive charge, and to the diminution of the majority tunneling current by the oxide potential barrier. The tunneling probabilities for majority and minority carriers are different; there are only a finite amount of majority carriers with thermionic energy greater than q(V_bi ? V_s) which can surmount the depletion potential and tunnel into the metal, whereas the photogenerated minority carriers derive kinetic energy in the depletion layer making tunneling easier. Transport coefficients for electrons to transmit from metal to semiconductor and from semiconductor to metal are different for the departure of built in potentials during illumination.     

Novel SONOS-Type Nonvolatile Memory Device With Optimal Al Doping in HfAlO Charge-Trapping Layer

Operation properties of polysilicon-oxide-nitride-oxide-silicon-type Flash device with HfAlO charge-trapping layer having various Al contents were investigated in this letter. Satisfactory performance in terms of operation speed, retention, and program/erase endurance of the Flash device is achieved with the optimal Al content of 18%-28% in the HfAlO trapping layer. In addition, high-speed operation can be attained with the combination of channel-hot-electron-injection programming and band-to-band hot hole erasing for NOR architecture applications.     

Nb3Si films with zero resistance Tc at 11.9 K fabricated by sputtering Nb on Si substrates

Dendritic textured Nb₃Si thin films, deposited by sputtering pure niobium onto silicon substrates, exhibit a rather high zero-resistance critical temperature, T_c. X-ray and TEM measurements reveal the films to be polycrystalline with the A15 phase. The resistance begins to drop sharply at a temperature of 13.3 K and down to zero at 11.9 K without residual resistivity.