Ultra-wideband Transmitter Research Articles

Fast neural network inverse model to maximize throughput in ultra-wideband WDM systems

Ultra-wideband systems expand the optical bandwidth in wavelength-division multiplexed (WDM) systems to provide increased capacity using the existing fiber infrastructure. In ultra-wideband transmission, power is transferred from shorter-wavelength WDM channels to longer-wavelength WDM channels due to inelastic inter-channel stimulated Raman scattering. Thus, managing launch power is necessary to improve the overall data throughput. While the launch power optimization problem can be solved by the particle swarm optimization method it is sensitive to the objective value and requires intensive objective calculations. Hence, we first propose a fast and accurate data-driven deep neural network-based physical layer in this paper which can achieve 99%−100% throughput compared to the semi-analytical approach with more than 2 orders of magnitude improvement in computational time. To further reduce the computational time, we propose an iterative greedy algorithm enabled by the inverse model to well approximate a sub-optimal solution with less than 6% performance degradation but almost 3 orders of magnitude reduction in computational time.

High data rate and energy efficient configurable IR-UWB transmitter with an integrated balun

This paper presents a novel, digitally configurable, switching oscillator-based impulse radio ultra-wideband (IR-UWB) transmitter that is robust to process variations. The pulse width and pulse position properties of the output waveform are configurable to ensure operation for the desired bandwidth and output pulse energy values. The architecture is based on a cross-coupled LC voltage-controlled oscillator (LC VCO) implemented with a custom-designed on-chip balun at a center frequency of 2.4 GHz. With the usage of this on-chip balun, the need for an extra buffer stage is eliminated, and the highest possible efficiency is achieved with the proper turns ratio selected. The generated digital control pulse signals are also used to ensure fast start-up and UWB operation while maintaining low power consumption with an implemented on/off tail switching scheme. The presented IR-UWB transmitter that occupies a total area of 0.35 mm2 is fabricated in the United Microelectronics Corporation (UMC) 180-nm mixed-mode/radio frequency (RF) CMOS process. The measured output voltage swing of the fabricated transmitter is 0.812 V on a 50-Ω load for the 200 Mb/s data rate, and the bandwidth is measured as 902 MHz. The achieved frequency tuning range is 1 GHz and the fabricated transmitter can drive 50 Ω, 75 Ω and 100 Ω loads with measured efficiency values 4.16%, 5.76%, and 4.05%, respectively. Compared to other works in the literature, this design achieves a higher output pulse energy at a higher data rate while maintaining low power consumption and, thus, high efficiency.

Cost analysis of ultrawideband transmission in optical networks

We examine the cost associated with increasing traffic on a reference transport network for both single- and multiband systems, with a total transmission bandwidth ranging from 4.8 to 20 THz (S2 + S1 + C + L-band, where S2 and S1 are the two halves of the S-band). The number and cost of amplifiers, transceivers, and fibers are considered. To ensure stable transmission power and simplified network management, we take noise loading into account. The optimal combination of transmission bands—for each system—is evaluated based on the maximization of the capacity calculated from the minimum per-band generalized signal-to-noise ratio of each band. The results reveal that, despite the lower spectral efficiency due to the higher fiber attenuation and band MUX/DEMUX insertion losses, multiband systems can effectively reduce the number of fibers needed, thus postponing the deployment of new fibers. The most cost-effective solution depends on the fiber and S-band amplifier costs and the forecast of the required network capacity. When additional fibers are freely available or fiber costs are minimal, employing a C-band-only system proves to be the most economical choice. As fiber costs increase, additional bands gradually become more appealing, progressing from the C-band-only to the C + L-band, and then to the addition of half of the S-band (S1 + C + L-band) or the whole S-band (S2 + S1 + C + L). Furthermore, multiband transmission systems are more attractive when considering higher traffic loads. We also propose an optimal order of deployment of transmission bands in a pay-as-you-grow approach. The corresponding cost evolution demonstrates that this approach is a viable solution to mitigate excessive costs during the initial stages of a network operation, even though it leads to an increased number of fibers and transceivers used before all transmission bands are enabled. Additionally, we show that the S1- and S2-bands have worse optical performance, making them more suitable for shorter lightpaths. Consequently, operating the S-band in single-hop links and simplifying the add-drop multiplexer architecture could be beneficial.

A THz smart switch based on a VO2 metamaterial that switches between wide-angle ultra-wideband absorption and transmission.

Terahertz (THz) devices are highly desired in modulation, detection, and receiving devices. Recently, active metamaterials have been applied as a novel strategy for the design of terahertz devices. However, their performance and function need to be further developed. Here, an active controllable THz smart switch is designed using vanadium dioxide (VO2), a thermally controlled phase transition material. The THz smart switch is simple, consisting of three layers: the top and bottom layers are VO2, and the intermediate dielectric layer is SiO2. Based on impedance matching theory and an analysis of the electric field distribution, the mechanism by which the device achieves perfect absorption is studied. The results show that the THz smart switch can achieve ultra-wideband and wide-angle absorption and transmission of terahertz waves, and can flexibly switch between these modes. When VO2 is in the metal state, the THz smart switch can achieve ultra-wideband absorption, and the absorption bandwidth is as high as 5.8 THz (A > 90%). When VO2 is in the insulating state, the THz smart switch can achieve ultra-wideband transmission, with an average transmission of 86% (Δf = 4.7 THz). As the ambient temperature changes, the THz smart switch can achieve active switching of the absorption from 2% to 99.9% and the transmission from 89% to 0%. It is worth noting that the THz smart switch can also realize the active switching of absorption and transmission over a wide-angle range. This study provides important insights for the design of active controllable devices and also offers a new concept for the design of THz multi-functional devices.

Microwave Angiography by Ultra-Wideband Sounding: A Preliminary Investigation.

Angiography is a very informative method for physicians such as cardiologists, neurologists and neuroscientists. The current modalities experience some shortages, e.g., ultrasound is very operator dependent. The computerized tomography (CT) and magnetic resonance (MR) angiography are very expensive and near infrared spectroscopy cannot capture the deep arteries. Microwave technology has the potential to address some of these issues while compromising between operator dependency, cost, speed, penetration depth and resolution. This paper studies the feasibility of microwave signals for monitoring of arteries. To this aim, a homogenous phantom mimicking body tissue is built. Four elastic tubes simulate arteries and a mechanical system creates pulsations in these arteries. A multiple input multiple output (MIMO) array of ultra-wideband (UWB) transmitters and receivers illuminates the phantom and captures the reflected signals over the desired observation time period. Since we are only interested in the imaging of dynamic parts, i.e., arteries, the static clutters can be suppressed easily by background subtraction method. To obtain a fast image of arteries, which are pulsating with the heartbeat rate, we calculate the Fourier transform of each channel of the MIMO system over the observation time and apply delay and sum (DAS) beamforming method on the heartbeat rate aligned spectral component. The results show that the lateral and longitudinal images and motion mode (M-mode) time series of different points of phantom have the potential to be used for diagnosis.

An efficient ultra-wideband digital transceiver for wireless applications on the field-programmable gate array platform

<p>The ultra-wideband (UWB) technology is a promising short-range communication technology for most wireless applications. The UWB works at higher frequencies and is affected by interferences with the same frequency standards. This manuscript has designed an efficient and low-cost implementation of IEEE 802.15.4a-based UWB-digital transceiver (DTR). The design module contains UWB transmitter (TX), channel, and UWB-receiver (RX) units. Convolutional encoding and modulation units like burst position modulation and binary phase-shift keying modulation are used to construct the UWB-TX. The synchronization and Viterbi decoder units are used to recover the original data bits and are affected by noise in UWB-RX. The UWB-DTR is synthesized using Xilinx ISE<sup>®</sup> environment with Verilog hardware description language (HDL) and implemented on Artix-7 field-programmable gate array (FPGA). The UWB-DTR utilizes less than 2% (slices and look-up table/LUTs), operates at 268 MHz, and consumes 91 mW of total power on FPGA. The transceiver achieves a 6.86 Mbps data rate, which meets the IEEE 802.15.4a standard. The UWB-DTR module obtains the bit error rate (BER) of 2×10<sup>-4</sup> by transmitting 105 data bits. The UWB-DTR module is compared with similar physical layer (PHY) transceivers with improvements in chip area (slices), power, data rate, and BER. </p>

Demonstration and Characterization of High-Throughput 200.5 Tbit/s S+C+L Transmission over 2x100 PSCF Spans

Recent advances in multi-band amplification support ultra-wideband (UWB) systems as a suitable solution to cope with the increasing fiber communications traffic demand. The combination of UWB with spectral-efficient modulation formats can significantly increase in the total throughput of wavelength division multiplexed (WDM) transmission systems. <p xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">In this work, we demonstrate a 240×70 Gbaud PCS-256QAM WDM transmission using an optical bandwidth of 150 nm across the S, C and L bands. We combine doped-fiber amplifiers, semiconductor optical amplifiers (SOA) and backward distributed Raman amplification to achieve 200.5 Tbit/s of total generalized mutual information (GMI) throughput over two 100 km pure-silica-core fibers (PSCFs). We also present the digital twin of this experiment, providing the impact of wavelength-dependent impairments on the system performance. Our results demonstrate the feasibility of high-throughput multi-span UWB transmission.

Ultra-wideband CMOS power amplifier for wireless body area network applications: a review

&lt;span lang="EN-US"&gt;A survey on ultra-wideband complementary metal-oxide semiconductor (CMOS) power amplifiers for wireless body area network (WBAN) applications is presented in this paper. Formidable growth in the CMOS integrated circuits technology enhances the development in biomedical manufacture. WBAN is a promising mechanism that collects essential data from wearable sensors connected to the network and transmitted it wirelessly to a central patient monitoring station. The ultra-wideband (UWB) technology exploits the frequency band from 3.1 to 10.6 GHz and provides no interference to other communication systems, low power consumption, low-radiated power, and high data rate. These features permit it to be compatible with medical applications. The demand target is to have one transceiver integrated circuit (IC) for WBAN applications, consequently, UWB is utilized to decrease the hardware complexity. The power amplifier (PA) is the common electronic device that employing in the UWB transmitter to boost the input power to the desired output power and then feed it to the antenna of the transmitter. The advance in the design and implementation of ultra-wideband CMOS power amplifiers enhances the performance of the UWB-transceivers for WBAN applications. A review of recently published CMOS PA designs is reported in this paper with comparison tables listing wideband power amplifiers' performance.&lt;/span&gt;

Ultrawideband RF-IQ Modulator Using Segmented Nonlinearly Scaled RF-DACs and Nonoverlapping LO Signals

A wideband Cartesian in-phase and quadrature (I/Q) modulator based on dual 10 b RF-digital-to-analog converters (DACs) is presented. Nonoverlapping local oscillator (LO) signals and a segmented nonlinear scaling with scaled unit cells contribute to a high linearity and allow for a low-complexity digital predistortion (DPD). Unit-cell flip-flops (FFs) and a balanced clock distribution enable a high sample rate with little skew. Out-of-band emissions are reduced through drive-slope control of the data-switch inputs. The modulator, implemented in the 22-nm fully-depleted silicon-on-insulator (FDSOI) CMOS, operates between 20 and 26 GHz with a peak sample rate of 11 GS/s. It has been used to demonstrate the transmission of a 64-quadrature amplitude modulation (QAM) single-carrier (SC) signal at 13.2 Gb/s, a 256-QAM SC signal at 7.33 Gb/s, and an orthogonal frequency division multiplexing (OFDM) signal comprising four aggregated 400-MHz 64-QAM channels with an error vector magnitude (EVM) of 6.43%. These results demonstrate the potential of the proposed modulator for the realization of ultrawideband transmitters in high-performance millimeter-wave (mmW) systems.

Design and Analysis of Impulse Radio (IR) Based UWB Transmitter with Antenna

The use of ultra-wideband (UWB) in target detection, radar and wireless connectivity, specifically in the medical world, has attracted a lot of attention. The concept that the IR-UWB system does not necessarily require carrier signals is one of its most appealing features. IR-UWB can transmit information using short Gaussian monocycle pulses. In light of these advantages, this paper proposes a novel UWB transmitter system which consists of UWB signal generating circuits and UWB antenna, which work together to create entire UWB transmitter. It is based on impulses and has a simple architecture with low power consumption. The proposed transmitter is realized in Cadence tools with 90nm CMOS technology and proposed UWB antenna is simulated using Advanced Design System (ADS) simulator software. In addition, the transmitter circuit and the antenna are co-simulated using ADS software. The illustrated UWB transmitter uses a low-power supply and generates pulse amplitude with pulse duration of for the Gaussian monocycle pulse. Due to its increased output voltage swing and reduced power consumption when comparing to other circuits, the proposed architecture is functional and suitable for use in short-range wireless networks and medical applications.

Innovation-Based Fault Detection and Exclusion Applied to Ultra-WideBand Augmented Urban GNSS Navigation

Due to their ability to provide a worldwide absolute outdoor positioning, Global Navigation Satellite Systems (GNSS) have become a reference technology in terms of navigation technologies. Transportation-related sectors make use of this technology in order to obtain a position, velocity, and time solution for different outdoor tasks and applications. However, the performance of GNSS-based navigation is degraded when employed in urban areas in which satellite visibility is not good enough or nonexistent, as the ranging signals become obstructed or reflected by any of the numerous surrounding objects. For these situations, Ultra-Wideband (UWB) technology is a perfect candidate to complement GNSS as a navigation solution, as its anchor trilateration-based radiofrequency positioning resembles GNSS’s principle. Nevertheless, this fusion is vulnerable to interferences affecting both systems, since multiple signal-degrading error sources can be found in urban environments. Moreover, an inadequate location of the augmenting UWB transmitters can introduce additional errors to the system due to its vulnerability to the multipath effect. Therefore, the misbehavior of an augmentation system could lead to unexpected and critical faults instead of improving the performance of the standalone GNSS. Accordingly, this research work presents the performance improvement caused by the application of Fault Detection and Exclusion methods when applied to a UWB-augmented low-cost GNSS system in urban environments.

Maximization or leveling: characterization of the trade-offs for the transmission throughput in ultrawideband optical transmission.

In ultrawideband transmission, the overall noise comes from the amplification, fiber properties at different wavelengths, and stimulated Raman scattering, and its impact on channels across transmission bands is different. This requires a range of methods to mitigate the noise impact. Performing channel-wise power pre-emphasis and constellation shaping, one can compensate for the noise tilt and attain maximum throughput. In this work, we study the trade-off between the goals of maximizing the total throughput and leveling the transmission quality for different channels. We use an analytical model for multi-variable optimization and identify the penalty from constraining the mutual information variation.

E-, S-, C- and L-band coherent transmission with a multistage discrete Raman amplifier.

We report for the first time an ultra-wideband coherent (UWB) WDM transmission over a 70 km standard single mode fibre (SSMF) solely using a multistage discrete Raman amplifier (DRA) over the E-, S-, C- and L-bands of the optical window. The amplifier is based on a split-combine approach of spectral bands enabling signal amplification from 1410-1605 nm over an optical bandwidth of 195 nm (25.8 THz). The proposed amplifier was characterized with 143 channelized amplified spontaneous emission (ASE) dummy channels in the S-, C- and L-bands and 4 laser sources in the E-band (1410-1605 nm). The amplification results show an average gain of 14 dB and a maximum noise figure (NF) of 7.5 dB over the entire bandwidth. Coherent transmission with the proposed amplifier was performed using a 30 Gbaud PM-16-QAM channel coupled with the ASE channels over a 70 km SMF. The ultra-wideband transmission using the tailored multistage DRA shows transmission bandwidth of 195 nm with a maximum Q2 penalty of ∼4 dB in E- and S-band, and ∼2 dB in C- and L-band.

Ultra-wideband transmission filter based on guided-mode resonances in two terahertz metasurfaces.

This paper reports on a broadband transmission filter that employs the guided mode resonances pertaining to a terahertz metasurface composed of metallic gold disks with a quartz slab. Unlike structures involving conventional metasurfaces, two identical metasurfaces are placed on the upper and lower sides of a thick quartz slab. This structure can excite both even and odd guided mode resonances. The interaction of the two resonances at similar frequencies produces a broadband transmission peak. The sharp spectral feature of each resonance leads to the abrupt degradation of the transmission at the spectral edge, which can enable the development of the filter application. The proposed scheme can facilitate practical applications such as those of broadband filters at a terahertz frequency.

Devices and Fibers for Ultrawideband Optical Communications

Wavelength-division multiplexing (WDM) has historically enabled the increase in the capacity of optical systems by progressively populating the existing optical bandwidth of erbium-doped fiber amplifiers (EDFAs) in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$C$ </tex-math></inline-formula> -band. Nowadays, the number of channels—needed in optical systems—is approaching the maximum capacity of standard <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$C$ </tex-math></inline-formula> -band EDFAs. As a result, the industry worked on novel approaches, such as the use of multicore fibers, the extension of the available spectrum of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$C$ </tex-math></inline-formula> -band EDFAs, and the development of transmission systems covering <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$C$ </tex-math></inline-formula> - and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$L$ </tex-math></inline-formula> -bands and beyond. In the context of continuous traffic growth, ultrawideband (UWB) WDM transmission systems appear as a promising technology to leverage the bandwidth of already deployed optical fiber infrastructure and sustain the traffic demand for the years to come. Since the pioneering demonstrations of UWB transmission a few years ago, long strides have been taken toward UWB technologies. In this review article, we discuss how the most recent advances in the design and fabrication of enabling devices, such as lasers, amplifiers, optical switches, and modulators, have improved the performance of UWB systems, paving the way to turn research demonstrations into future products. In addition, we also report on the advances in UWB optical fibers, such as the recently introduced nested antiresonant nodeless fibers (NANFs), whose future implementations could potentially provide up to 300-nm-wide bandwidth at less than 0.2 dB/km loss.

A 1.15-mW Low-Power Low-Complexity Reconfigurable FM-UWB Transmitter

A 1.15-mW 3.75–4.25-GHz frequency-modulated ultrawideband (FM-UWB) transmitter (TX) is fabricated in 65-nm CMOS, with digitally reconfigurable subcarrier frequencies, UWB bandwidth, and radio frequency (RF) frequency band. Low-complexity submodules are utilized with significant power savings. An ultralow-current hybrid module is for bandgap reference (BGR) and power-ON reset (POR), and a single-ended crystal oscillator (XO) generates a 12-MHz clock reference. A dual-path ring voltage-controlled oscillator (VCO) conducts linear RF FM, followed by a push–pull power amplifier (PA) for 100-kb/s wireless data transmission. A differential relaxation oscillator (OSC) is for subcarrier generation, and an intermittent dual-mode frequency calibration loop ensures system robustness. Experimental results show that the presented FM-UWB TX successfully generates an Federal Communications Commission (FCC)-compliant UWB signal, with an energy efficiency of 11.5 nJ/bit and an active area of 0.21 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> from a 1-V supply. The 2.25- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{A}$ </tex-math></inline-formula> hybrid BGR and POR achieves a temperature coefficient of 32 ppm/°C, a line regulation of 2.3%/V, a supply-ramp-rate-tolerant power-ON, and brown-out function. The 40- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{W}$ </tex-math></inline-formula> XO features a low-frequency inaccuracy of 4 ppm/V. The 40- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{A}$ </tex-math></inline-formula> relaxation OSC provides the reconfigured two-frequency shift keying (FSK) triangular amplitude and frequency. The 2.79–5.18-GHz 0.6-mW ring VCO is capable of providing the phase noise performance of −77 dBc/Hz at the 1-MHz offset, followed by the 0.45-mW PA having the output power higher than −14 dBm and the peak power-added efficiency (PAE) of 29.6%. All these benefit low-power low-cost TX implementation, where the carrier and subcarrier frequencies are calibrated by an intermittent digital loop with omitted power dissipation.

3–5 GHz FSK-OOK ultra wideband transmitter based on memristive ring oscillator

3–5 GHz FSK-OOK ultra wideband transmitter based on memristive ring oscillator

On the impact of launch power optimization and transceiver noise on the performance of ultra-wideband transmission systems [Invited

Ultra-wideband transmission is a promising, cost-effective solution to meet the increasing demand for data traffic in optical fiber systems. However, system performance and quality of transmission (QoT) are limited by fiber nonlinearity, in particular, interchannel stimulated Raman scattering (ISRS), leading to a power transfer from short to long wavelengths. As the result, per-channel launch power optimization is required to maximize the system throughput. In this paper, we investigate how the transceiver noise and launch power optimization impact the total throughput and the per-channel QoT for transmission bandwidths of up to 20 THz, using the S-, C-, and L-bands. To measure the gains through the optimum launch power profile, a spectrally uniform launch power is used as a baseline. Through experimental analysis and theoretical modeling, the main limitations constraining the achieved data throughput of 178 Tb/s over a continuous bandwidth of 16.83 THz and 40 km were investigated. The impact of the launch power optimization and the transceiver constrained signal-to-noise ratio (SNR) are analyzed and compared, and the approaches to overcome data throughput limitations are considered. An extensive theoretical investigation for different system configurations is described, demonstrating the trade-off between ISRS impact and transceiver noise. The former degrades the QoT and increases the gains in performance obtained by optimizing the launch power, while the latter reduces these gains and the SNR variation across the bandwidth, with a major impact over short distances.

UWB Fastly–Tunable 0.5–50 GHz RF Transmitter Based on Integrated Photonics

Currently, due to the 6G revolution, applications ranging from communication to sensing are experiencing an increasing and urgent need of software-defined ultra-wideband (UWB) and tunable radio frequency (RF) apparatuses with low size, weight, and power consumption (SWaP). Unfortunately, the coexistence of ultra-wideband and software-defined operation, tunability and low SWaP represents a big issue in the current RF technologies. Recently, photonic techniques have been demonstrated to support achieving the desired features when applied in RF UWB transmitters, introducing extremely wide operation and instantaneous bandwidth, tunable filtering, tunable photonics-based microwave mixing with very high port-to-port isolation, and intrinsic immunity to electromagnetic interferences. Moreover, the recent advances in photonics integration also allow to obtain very compact devices. In this article, to the best of our knowledge, the first example of a complete tunable software-defined RF transmitter with low footprint (i.e., on photonic chip) is presented exceeding the state-of-the-art for the extremely large tunability range of 0.5–50 GHz without any parallelization of narrower-band components and with fast tuning (<200 μs). This first implementation represents a breakthrough in microwave photonics.

A Design of Wideband Microstrip-to-Microstrip Vertical Transition for RF Circuits

With the miniaturization of RF circuits, the transmission of signals in different layers becomes important. How to realize the vertical transition structure with wide transmission band and low loss has become the focus of research. In this paper, we proposed a broadband vertical transition structure design based on cavity coupling. This model achieves broadband coupling between the upper and lower microstrips by adding parabolic patches, which improves the model transmission bandwidth. The simulation results show that the optimized model has ultra-wideband transmission characteristic, the 1dB bandwidth is 3.32 GHz-10.42 GHz and the fractional bandwidth is more than 103%. What’ more, the thick ground layer of the model improves the heat dissipation performance. Therefore, this structure is very suitable for high-speed and high-density RF circuits.