Wide Bandwidth Range Research Articles

A 4.3 GB/s Mobile Memory Interface With Power-Efficient Bandwidth Scaling

This paper presents a 4.3 GB/s mobile memory interface that utilizes low power states with rapid transition times to support power efficient signaling over a wide range of effective bandwidths. The fastest power state transition is implemented by a global synchronous clock pause that gates dynamic power consumption without any loss of system state. Extensive use of CMOS circuit topologies, with low static power consumption, provides maximum power savings when the clocks are paused. The memory controller forwards a half bit-rate clock to the memory for synchronous communication, which is similarly paused in the low power state. Thus, dynamic interface power on the memory itself naturally responds to the clock pausing, without any explicit communication from the controller or special low-power state on the memory. Low-swing differential signaling based on a push-pull voltage mode driver results in good signal integrity and power efficiency at peak activity. Test-chips fabricated in a 40 nm low-power CMOS technology achieve 3.3 mW/Gb/s power efficiency at 4.3 GB/s data bandwidth, and support better than 5 mW/Gb/s operation over a range from 0.03 to 4.3 GB/s.

Investigation of higher order optical multiple pulse position modulation links over a highly dispersive optical channel

This study describes a performance analysis of eight different multiple pulse position modulation (PPM) systems with 4, 7, 12, 15, 17, 22, 28 and 33 slots operating over a plastic optical fibre (POF) channel. The receiver/decoder uses slope detection and a maximum likelihood sequence detector (MLSD). As the analysis of any multiple pulse position modulation (MPPM) system is extremely time consuming, especially when the number of slots is large, a software solution was used. A measure of coding quality that accounts for efficiency of coding and bandwidth expansion was applied and original results showed that the middle systems of these MPPM families are the most efficient for a wide range of bandwidths. Although the efficient Gray coding was used for this investigation, a close to optimum mapping is presented for MPPM systems of the families mentioned above. These mappings were found to be superior to the efficient Gray codes, linear coding and a series of random mappings.

Microresonators in CMOS Compatible Substrate

We report our recent progress in designing and developing traveling-wave microresonators on CMOS compatible substrate, with a focus on ultra-compact Si-based microring and microdisk resonators in the visible and near infrared wavelengths with ultra-high Q and small mode volume, suitable for strong light-matter interaction. The performance of these resonators is discussed, and the design and fabrication challenges and solutions to achieve efficient coupling from the bus-waveguide to the resonator is mentioned. Coupled-resonator architectures for the design of filters are analyzed and theoretical and experimental results for the flat-band filters with wide bandwidth and large free spectral range are presented. Furthermore, by using a detailed thermal model we demonstrate optimized microresonator structures on semiconductor substrates with improved thermal conductivity that can sustain a high circulating optical intensity at the resonance wavelength, which is particularly useful for nonlinear optics and optical signal processing applications. Finally, we address some of the applications and future prospects of such microresonators in CMOS-compatible substrate technology, including portable multi-purpose bio/chemical sensing systems, reconfigurable optical signal processing modules and chip-scale optical amplifiers and lasers.

A 250 MHz 14 dB-NF 73 dB-Gain 82 dB-DR Analog Baseband Chain With Digital-Assisted DC-Offset Calibration for Ultra-Wideband

A 250 MHz analog baseband chain for ultra-wideband was implemented in a 1.2 V 0.13 ? m CMOS process. The chip has an active area of 0.8 mm2. In the analog baseband, PGAs and filters are carried out by current-mode amplifiers to achieve wide bandwidth and wide dynamic range of gain, as well as low noise and high linearity. Besides, a current-mode Sallen-Key low-pass filter is adopted for effective rejection of out-of-band interferers. A 6 th-order Chebyshev low-pass filter realized in Gm-C topology is designed in the baseband chain for channel selection. Digitally-assisted DC-offset calibration improves second-order distortion of the entire chain. The design achieves a maximum gain of 73 dB and a dynamic range of 82 dB. Measured noise figure is 14 dB, an IIP3 of -6 dBV, and IIP2 of -5 dBV at the maximum gain mode. The analog baseband chain consumes 56.4 mA under supply of 1.2 V.

Traffic design to reduce the number of OEO conversions in multi-stage access network

It is important to realize the efficient accommodation of access traffic for various services that will have a wide dynamic range of bandwidth. To achieve this, we are studying a new access network based on multi-stage semiconductor optical amplifiers (SOAs), which has a multi-access point that separately accommodates different services. This paper describes the configuration and advantage of this network and presents a traffic design obtained by simulations that examined the number of optical-electrical-optical (OEO) conversions at first-in first-out (FIFO) controlling packets with a view to reducing power consumption.

Space-frequency linear dispersion codes for single carrier-frequency domain equalization

This letter addresses the application of Linear Dispersion Codes (LDC) in space and frequency domains in Single Carrier-Frequency Domain Equalization (SCFDE) systems. Space-frequency (SF)-LDCs are more suitable than space-time (ST) LDC in high mobility environments. However, the application of LDCs in space and frequency domains in SCFDE systems is not straightforward as in orthogonal frequency division multiplexing (OFDM) systems because in this case there is no direct access to subcarriers at the transmitter. This letter shows that it is possible to induce a target SF symbol dispersion in SCFDE by using a simple linear pre-coder and a conventional LDC that spreads the symbols in time and space domains according to specific ST dispersion matrices. The letter shows how to derive the ST dispersion matrices to be used at the transmitter as a function of the dispersion matrices describing the target SF dispersion. The presented procedure can be applied to both pure transmit diversity and pure multiplexing schemes, which are special cases of LDCs. Therefore, the proposed scheme provides a low complexity implementation of any dispersion in space and frequency over SCFDE systems, which alternatively would require the use of FFT/IFFT also at the transmitter side. The letter also shows a performance comparison of SF-LDCs and ST-LDCs in a typical propagation environment for future radio systems. The comparison confirms the suitability of using the dispersion in frequency rather than time for a wide range of coherence bandwidths.

Widely tunable low-power high-linearity current-mode integrator built using DG-MOSFETs

A novel tunable current-mode integrator for low-voltage low-power applications is presented using mixed-mode TCAD simulations. The design is based on independently driven double-gate (IDDG) MOSFETs, a nano-scale four-terminal device, where one gate can be used to change the characteristics of the other. Using current-mirrors built with IDDG-MOSFETs, we show that the number of active devices in the tunable current-mode integrator, 16 in bulk CMOS design, may be halved, i.e. considerable savings in both total area and power dissipation. The integrator operates with single supply voltage of 1 V and a wide range of tunable bandwidth (~2 decades) and gain (~30 dB). This linear circuit has third-order harmonic distortion as low as ?70 dB in appropriate bias conditions, which can be set via the back-gates. The impact of tuning on the IDDG integrator and conventional design using symmetrically driven (SDDG) MOSFETs is comparatively studied. The proposed design is a good example for performance leverage through IDDG MOSFET architectures in analog circuits integral to future mixed-signal systems.

Cladding-modulated Bragg gratings in silicon waveguides

A cladding-modulated Bragg grating implemented using periodic placements of cylinders along a waveguide is proposed in a silicon-on-insulator platform. The coupling strength is varied by changing the distance between the cylinders and the waveguide. This implementation enables precise control and a wide dynamic range of coupling strengths and bandwidths that can be practically achieved for applications with specific bandwidth requirements. Modeling results are verified experimentally, and we demonstrate coupling strengths differing by 1 order of magnitude (43 and 921 per cm) with bandwidths of 8 and 16 nm, respectively. This method scheme enables weakly coupled devices with high fabrication tolerance to be realized.

3-D Data Storage, Power Delivery, and RF/Optical Transceiver—Case Studies of 3-D Integration From System Design Perspectives

Three-dimensional (3-D) integration of systems by vertically stacking and interconnecting multiple materials, technologies, and functional components offers a wide range of benefits, including speed, bandwidth and density increase, power reduction, small form factor, packaging reduction, yield and reliability increase, flexible heterogeneous integration with multifunctionality, and overall cost reduction. A new spectrum of opportunities and challenges arises for integrated system designers, which warrants rethinking and innovations from system design perspectives. By selecting three representative cases, i.e., solid-state data storage, power delivery, and hybrid radio-frequency/optical transceiver for distributed sensor networks, this paper intends to exemplify the potentials of exploiting the benefits of 3-D integration technology from system perspectives.

Inference on a regression model with noised variables and serially correlated errors

Motivated by a practical problem, [Z.W. Cai, P.A. Naik, C.L. Tsai, De-noised least squares estimators: An application to estimating advertising effectiveness, Statist. Sinica 10 (2000) 1231–1243] proposed a new regression model with noised variables due to measurement errors. In this model, the means of some covariates are nonparametric functions of an auxiliary variable. They also proposed a de-noised estimator for the parameters of interest, and showed that it is root- n consistent and asymptotically normal when undersmoothing is applied. The undersmoothing, however, causes difficulty in selecting the bandwidth. In this paper, we propose an alternative corrected de-noised estimator, which is asymptotically normal without the need for undersmoothing. The asymptotic normality holds over a fairly wide range of bandwidth. A consistent estimator of the asymptotic covariance matrix under a general stationary error process is also proposed. In addition, we discuss the fitting of the error structure, which is important for modeling diagnostics and statistical inference, and extend the existing error structure fitting method to this new regression model. A simulation study is made to evaluate the proposed estimators, and an application to a set of advertising data is also illustrated.

Impact of Design on High-Frequency Performance of Advanced MIM Capacitors Using Si$_{3}$N$_{4}$ Dielectric Layers

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> High-frequency characterizations of ultra thin 32 nm PECVD Si<formula formulatype="inline"><tex Notation="TeX">$_{3}$</tex></formula>N<formula formulatype="inline"> <tex Notation="TeX">$_{4}$</tex></formula> dielectric in an advanced metal–insulator–metal (MIM) capacitors are presented, with focus on the impact of design on the performance of MIM capacitors. Frequency dependent capacitance has been extracted over a wide range of frequency bandwidth. An equivalent model circuit of capacitors including four parameters was developed to explain this behavior. The results have been compared with the values obtained from a 3-D electromagnetic modeling. A specific chart has been introduced to predict the electrical performance of new MIM capacitor designs. </para>

Development of Radar Absorbing Nano Crystals under Thermal Irradiation

Single phase W-type barium hexaferrite nano crystals of radar absorbing material (RAM) i.e., BaMe2Fe16O27 (Me2+=Fe2+) were synthesized by a modified flux method that combines the controlled chemical co-precipitation process for nucleation and complete uniform growth during in-situ annealing with NaCl flux under vacuum furnace. Uniform structure morphological transformation of nano crystals from spherical to prism faces were noticed after annealing with increasing temperatures from 200 to 1200 oC for 4 h in vacuum. XRD results showed the single phase nanocrystals of BaFe18O27 with increasing crystallanity and size from 10 to 90 nm during annealing. FESEM and TEM were used to investigate the systematic growth processes of various morphologies of nano crystals. The effect of such systematic morphological transformation of nanocrystals was observed in dielectric, dynamic magnetic and refection loss (RL) properties in Kuband (12.4 -18.0 GHz). A significant increment from -15.23 dB to -43.65 dB with wide range of bandwidth in RL loss is noticed due to the symmetric morphological growth of single phase nano crystals of RAM during annealing. This process of crystal growth, morphology evolution and RL enhancement with respect to increasing temperature were also explained in terms of ostwald ripening and quantum size effect.

Compact wide-slot antenna for ultra-wideband communications

A novel microstrip-line-fed wide-slot antenna is proposed. Investigations on the prototype of the bevelling square slot design with a small tail slot were employed to increase the wide impedance bandwidth range. The proposed antenna has a simple, symmetric structure and compact size. The matching impedance below 2:1 VSWR is applicable to ultra-wideband communications (3.1–10.6 GHz) with proper choices of bevel of the slot and the size of the tail slot cut in the ground plane.

V-SHAPED MONOPOLE ANTENNA FOR BROADBAND APPLICATIONS

In this paper, design and analysis of a novel broadband V-shaped monopole antenna is presented. The proposed antenna has a simple configuration to fabricate with low cost. The antenna is composed of two elliptical conducting plates connected to the two edges of a small horizontal rectangular plate and placed over a small circular ground plane. The designed antenna has a very wide bandwidth range of 3-18 GHz, low cross polarization, relatively high gain and good far-field radiation characteristics in the entire operating bandwidth. To obtain the broad bandwidth, the antenna dimensions have been optimized. A comprehensive parametric study has been carried out to understand the effects of various parameters and to optimize the performance of the final design. The designed antenna is simulated with software packages CST microwave studio and Ansoft' HFSS in the operating frequency range. Simulation results for VSWR and far-field radiation patterns of the antenna over the frequency band 3-18 GHz are presented and discussed.

Adaptable vibration absorber employing a magnetorheological elastomer with variable gap length and methods and systems therefor

The inventions include an adaptive vibration absorber (AVA) and variation thereof including variations in methods and systems of usage. An exemplary AVA may operate adaptively over an appropriate relatively wide bandwidth or frequency range in vibration absorption without adding energy to the system and the problems associated with such energy addition. Further, the exemplary AVA may be of low cost as well sa lightweight and compact.

Investigation of an optical multiple PPM link over a highly dispersive optical channel

A performance analysis of (X/Y) multiple pulse position modulation (PPM) systems, in which X denotes the number of data slots and Y the number of pulses, operating over a plastic optical fibre channel has been described. The effects of receiver noise and channel dispersion are accounted for and the manner in which the erasure, wrong-slot and false-alarm errors affect the system performance is examined. The receiver/decoder uses slope detection and a maximum likelihood sequence detector. As the analysis of any (x/y) multiple PPM system is extremely time-consuming, a novel automated solution was designed to predict the equivalent pulse code modulation (PCM) error rates of specific sequences and to simplify the task. A measure of coding quality that accounts for efficiency of coding and bandwidth expansion has also been proposed. Using this measure, original results show that a (12/6) system is the most efficient for a wide range of bandwidths.

Enhanced transmission and directional emission via coupled-resonator optical waveguides

We propose a novel photonic crystal waveguide configuration consisting of coupled-resonator optical waveguides at the termination to obtain enhanced transmission and beaming of light. We show theoretically that such a configuration can collimate the light output from a photonic crystal waveguide over a wide bandwidth range. The mechanism explained in this paper may be easily extrapolated to the photonic crystal configuration of air holes in a dielectric substrate.

Minimising intersymbol interference in optical-fibre dicode PPM systems

Dicode pulse-position modulation (PPM) has been proposed as an alternative modulation format to conventional digital PPM, since it offers comparable receiver sensitivities while operating at significantly lower slot-clock rates. A recent numeric analysis considered the performance of dicode PPM, using slope detection, in a dispersive environment. In this paper, consideration is given to an alternative detection strategy, and new results are presented that show that intersymbol interference (ISI) can be eliminated through the use of central decision detection combined with raised cosine filtering. This leads to a more simplified receiver design and results in equivalent sensitivity performance at high fibre bandwidths and significantly improved performance at lower fibre bandwidths. Practical approximations to this approach are considered and design rules presented for determining the bandwidth of both the preamplifier and a simple 3rd order Butterworth equalisation filter. It is shown that setting the bandwidth of both the preamplifier and equaliser to 0.6 times the dicode slot rate gives sensitivities within 0.2 dB of ideal dicode PPM raised cosine filtering, and that such a receiver can operate over a wide range of fibre bandwidths, with minimal degradation in sensitivity.

IMAGIS, a PACS software solution for the National Health System in Cuba

Elastic Internet applications have the greatest share in the traffic transported over the Internet today. Web access and e-mail are the most popular applications among most people using the Internet. Although these applications can well adapt to a wide range of bandwidths, their performance is an issue to people using services interactively.In this paper, we use sophisticated application-level evaluations to extract traffic characteristics and performance measures for HTTP, SMTP and POP3 from traffic traces. The process of loading Web pages by real browsers using persistent and parallel connections is studied in detail, revealing statistics about the elements in Web pages as well as the number of parallel connections and the accumulated waiting time during Web page loads.The main results are: (1) High variance distributions are not only found as expected in file sizes, but also in the number of items in a Web page, the number of e-mails transmitted in one connection, the duration of SMTP command exchanges or even the users' viewing times for Web pages. (2) Web browsers utilize more parallel connections than usually expected to simultaneously load items. (3) A large portion of the delay in Web page retrievals or e-mail transfers is due to serial waiting and can therefore not be significantly reduced by increasing bandwidths. Therefore, low latency is as much an issue in access systems as high bandwidth.

Two‐dimensional array of rectangular slot antennas tuned with patch stubs for wide bandwidth and large scanning range

AbstractThis paper presents a 2D array design composed of rectangular slot antennas tuned with patch stubs. The 2D array of 32 × 32 elements for phased‐array applications achieves a 38‐dB gain, 60% impedance bandwidth, and 65° scanning angle without grating lobes. The return loss, radiation patterns, scanning capabilities, and gain are presented. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 149–152, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20752