High-speed Signal Research Articles

Tensile Strength Property with PdCo-Cu Multi-Layer Lamination and Heat Treatment of MEMS Probe for Probe Card

Cantilever wire probe card has limited to transport high-speed signal because of long wire but it is suitable for inspecting high-current and high voltage semiconductor such as wide band gap (WBG) power semiconductors.Superior mechanical property of a probe card wire is in demand because it is respectively used wafer inspection with in and out pad on the top surface of the power semiconductor wafer. Therefore, in this study, tensile specimens of micro electro-mechanical systems (MEMS) probe alternatively layered and electroplated with palladium (Pd)-cobalt (Co) alloy layers and copper (Cu) layers. MEMS probe was also measured tensile strength and elongation with multi-lamination and heat treatment conditions. Additionally, fractography of fracture surface after tensile test were analyzed using a scanning electron microscope (SEM). As the number of PdCo-Cu multi-layer increased, 11, 15 and 21 layered specimens showed higher tensile strength and longer elongation than 5 layered specimens because of the increase of laminated interface of PdCo and Cu. 7 layered specimen after isothermal aging had higher tensile strength and longer elongation than before isothermal aging. In 5, 11, 15 and 21 layered specimens, the fracture surfaces of tensile test specimens without aging treatment showed a ductile-brittle mixed fracture mode. Fracture surfaces of 7-layered specimen before and after isothermal aging showed a ductile-brittle mixed fracture mode.

Quantitative Evaluation of Deformation in High-Speed Magnetic Flux Leakage Signals for Weld Defects in Oil and Gas Pipelines

Complex multiphase flow in oil and gas pipelines raises safety risks. Magnetic flux leakage (MFL) detection effectively identifies pipeline defects. However, the high-speed movement of MFL inspection tools induces motion-induced eddy currents (MIECs), complicating defect recognition and quantification. Most prior research has primarily focused on rectangular defects, leaving a gap in understanding the impact of MIECs on weld defects. This paper proposes the amplitude and shape deformation coefficients to analyze the influence of velocity on various weld defects, including internal reinforcement, lack of penetration, crack, external corrosion, internal corrosion, porosity, and lack of fusion. Utilizing these coefficients, this study examines the influence of the defect size and magnetizer configuration on these velocity-induced effects. The results show that the shape deformation coefficients range from 2.75 to 3.57 for Bx and from −0.13 to −0.3 for By, indicating a significant change in the MFL signal shape at 10 m/s compared to 0 m/s. The amplitude deformation coefficients for lack of penetration, internal corrosion, and porosity range from −0.01 to 0.1 for Bx, and from 0.86 to 0.98 for By, suggesting a decrease in peak-to-peak values. In contrast, other defects exhibit an increase in peak-to-peak values, indicating that the velocity effect may enhance the MFL signal. Also, the defect size and magnetizer configuration can affect the velocity effect on signals. These findings provide essential guidance for quantifying defect sizes and a solid foundation for designing more effective magnetization devices.

Signal processing for enhancing railway communication by integrating deep learning and adaptive equalization techniques.

With the increasing amount of data in railway communication system, the conventional wireless high-frequency communication technology cannot meet the requirements of modern communication and needs to be improved. In order to meet the requirements of high-speed signal processing, a high-speed communication signal processing method based on visible light is developed and studied. This method combines the adaptive equalization algorithm with deep learning and is applied to railway communication signal processing. In this research, the wavelength division multiplexing (WDM) and orthogonal frequency division multiplexing (OFDM) techniques are used, and fuzzy C equalization algorithm is used to softly divide the received signals, reduce signal distortion and interference suppression. The experimental results showed that increasing the step size could reduce the equalization effect, while increasing the modulation parameter will increase the bit error rate. Through deep learning to achieve channel equalization, visible light communication could effectively mitigate multi-path transmission and reflection interference, thereby reducing the bit error rate to the level of 0.0001. Under various signal-to-noise ratios, the system using the channel compensation method achieved the lowest bit error rate. This outcome was achieved by implementing hybrid modulation scheme, including Wavelength division multiplexing (WDM) and direct current-biased optical orthogonal frequency division multiplexing (DCO-OFDM) techniques. It has been proved that this method can effectively reduce the channel distortion when the receiver is moving. This study develops a dependable communication system, which enhances signal recovery, reduces interference, and improves the quality and transmission efficiency of railway communication. The system has practical application value in the field of railway communication signal processing.

Wafer-scale fabrication of InGaP-on-insulator for nonlinear and quantum photonic applications

The development of manufacturable and scalable integrated nonlinear photonic materials is driving key technologies in diverse areas, such as high-speed communications, signal processing, sensing, and quantum information. Here, we demonstrate a nonlinear platform—InGaP-on-insulator—optimized for visible-to-telecommunication wavelength χ(2) nonlinear optical processes. In this work, we detail our 100 mm wafer-scale InGaP-on-insulator fabrication process realized via wafer bonding, optical lithography, and dry-etching techniques. The resulting wafers yield 1000 s of components in each fabrication cycle, with initial designs that include chip-to-fiber couplers, 12.5-cm-long nested spiral waveguides, and arrays of microring resonators with free-spectral ranges spanning 400–900 GHz. We demonstrate intrinsic resonator quality factors as high as 324 000 (440 000) for single-resonance (split-resonance) modes near 1550 nm corresponding to 1.56 dB/cm (1.22 dB/cm) propagation loss. We analyze the loss vs waveguide width and resonator radius to establish the operating regime for optimal 775–1550 nm phase matching. By combining the high χ(2) and χ(3) optical nonlinearity of InGaP with wafer-scale fabrication and low propagation loss, these results open promising possibilities for entangled-photon, multi-photon, and squeezed light generation.

High-Speed Signal Optimization at Differential VIAs in Multilayer Printed Circuit Boards

The number of Printed Circuit Board (PCB) layers is continually increasing with the increase in data transmission rates, and the Signal Integrity (SI) of high-speed digital systems cannot be ignored. Introducing Vertical Interconnect Accesses (VIAs) in PCBs can realize the electrical connection between the top layer and the inner layers, however, VIAs represent one of the most important reasons for discontinuity between the PCBs and package. In this paper, a new optimization scheme for a differential VIA stub is proposed, with 3D full-wave numerical simulation used for modeling and simulation. Results show that this scheme optimizes the return loss and insertion loss while making the signal eye diagram more ideal, which can improve the transmission effect of high-speed signals.

Research on high-speed digital optical signal jitter measurement technology based on clock recovery algorithm using eye diagram opening area

With the rapid development of information technology, high-speed digital optical signal transmission technology has become the core of modern communication networks. However, the increase in transmission rates brings challenges such as noise, distortion, and interference, which affect the accuracy of clock recovery. To address these issues, this study proposes a clock recovery algorithm based on the eye diagram opening area to improve the accuracy and efficiency of high-speed digital optical signal jitter measurement. The proposed method extracts clock information from the signal using the opening area and curvature characteristics of the eye diagram for jitter measurement. Experimental results demonstrate that the clock recovery algorithm based on the eye diagram opening area can stably reconstruct the signal eye diagram and obtain jitter parameters under different optical power conditions. At optical powers of −7.2 dBm, −12.2 dBm, and −17.2 dBm, the Q-factors were 8.8, 7.6, and 4.3, respectively, and the RMS jitter values were 12.2 ps, 13.4 ps, and 21.2 ps, respectively. At optical powers of −2.3 dBm, 0.1 dBm, 2.4 dBm, 4.6 dBm, and 6.0 dBm, the Q-factors were 9.1, 9.3, 9.5, 9.7, and 10.0, respectively, and the average jitter values were 8.9 ps, 8.5 ps, 8.0 ps, 7.5 ps, and 7.0 ps. These results indicate that the proposed algorithm performs excellently under low optical power conditions and maintains high recovery accuracy even when jitter increases at higher optical powers. The clock recovery algorithm based on the eye diagram opening area significantly improves the accuracy and stability of high-speed digital optical signal jitter measurement, enriches the theoretical research of clock recovery algorithms, and shows significant advantages in improving signal transmission quality, reducing bit error rate, and enhancing communication link reliability. The research outcomes provide key technical support for the optimization of modern high-speed optical communication systems.

Advancing LWIR FSO communication through high-speed multilevel signals and directly modulated quantum cascade lasers

This study investigates the potential of long-wave infrared (LWIR) free-space optical (FSO) transmission using multilevel signals to achieve high spectral efficiency. The FSO transmission system includes a directly modulated-quantum cascade laser (DM-QCL) operating at 9.1 µm and a mercury cadmium telluride (MCT) detector. The laser operated at the temperature settings of 15°C and 20°C. The experiment was conducted over a distance of 1 m and in a lab as a controlled environment. We conduct small-signal characterization of the system, including the DM-QCL chip and MCT detector, evaluating the end-to-end response of both components and all associated electrical elements. For large-signal characterization, we employ a range of modulation formats, including non-return-to-zero on-off keying (NRZ-OOK), 4-level pulse amplitude modulation (PAM4), and 6-level PAM (PAM6), with the objective of optimizing both the bit rate and spectral efficiency of the FSO transmission by applying pre- and post-processing equalization. At 15°C, the studied LWIR FSO system achieves net bitrates of 15 Gbps with an NRZ-OOK signal and 16.9 Gbps with PAM4, both below the 6.25% overhead hard decision-forward error correction (6.25%-OH HD-FEC) limit, and 10 Gbps NRZ-OOK below the 2.7% overhead Reed-Solomon RS(528,514) pre-FEC (KR-FEC limit). At 20°C, we obtained net bitrates of 14.1 Gbps with NRZ-OOK, 16.9 Gbps with PAM4, and 16.4 Gbps with PAM6. Furthermore, we evaluate the BER performance as a function of the decision feedback equalization (DFE) tap number to explore the role of equalization in enhancing signal fidelity and reducing errors in FSO transmission. Our findings accentuate the competitive potential of DM-QCL and MCT detector-based FSO transceivers with digital equalization for the next generation of FSO communication systems.

Dual-band hybrid fiber-wireless delivery system for high-speed data communications in CRAN based on polarization multiplexing with switching capabilities

This work presents a Radio-over-Fiber architecture for Cloud Radio Access Networks (CRAN) based on polarization division multiplexing for delivering up-converted high-speed data signals using a single laser-photodetector pair and free of polarization tracking devices. This system enables the allocation of data signals in two different bands defined as low-frequency (5–25 GHz) and high-frequency (55–65 GHz) millimeter waves (mmWave). Polarization multiplexing ensures minimal crosstalk when data signals are photonically up-converted while providing all-optical inter-band switching capabilities. Proof-of-concept experiments have been performed by simultaneously transmitting NRZ and multi-carrier modulated (Discrete Multitone - DMT) data signals over a radio-over-fiber link consisting of 1 km of standard optical fiber and radio transmission in the 7.5 GHz (wired) and 60 GHz (wireless) bands, respectively, with an estimated potential total throughput of at least 7.5 Gbps when considering the transmission of NRZ signals in these mmWave carriers. Results exhibit a BER below the FEC limit of 3.8 × 10−3 in all cases analyzed when the received optical power at the remote radio head (RRH) is above −4 dBm. The reduced number of components and versatility of this implementation provide a cost-effective solution for delivering and switching high-speed data signals in RF fronthaul for future 5G/6G communications.

Polyphenylene oxide/SiO2 composites: Towards ultra-low dielectric loss and high thermal conductivity of microwave substrates

With the rapid development of electronic information industry has raised the requirements for the performance of electronic components. Therefore, it is essential to research dielectric substrate materials with excellent dielectric properties and good thermal conductivity at high frequencies. This study introduced vinyl trimethoxysilane (VTMS) surface-functionalized silicon dioxide (SiO2) into the polyphenylene oxide/styrene–butadiene–styrene/triallyl isocyanurate (PST) composite resin to prepare PST/V-SiO2 composite. The microwave composite substrates for high-speed signal propagation were prepared through a process involving scraping coating and hot pressing. The study investigated the impact of varying amounts of V-SiO2 on the dielectric property, thermal stability, and thermal conductivity of the composites. The microwave composite substrates exhibit excellent dielectric properties and good thermal conductivity. When the V-SiO2 content is 80 wt%, the dielectric loss is 1.8 × 10-3 with a low dielectric constant (≤3.23@10 GHz). Furthermore, the PST/V-SiO2 composite displays higher thermal conductivity (0.735 W/(m·K)) and low moisture absorption. This research provides a novel strategy to develop microwave composite substrates with low dielectric loss and high thermal conductivity.

Binary Adder, Subtractor and Parity Checker Based on Optical Logic Gates

We propose schemes for binary adder, subtractor and parity checker using optical logic gates. These schemes could be useful for calculations using optical systems. Utilizing optical logic gates, we can achieve functions of binary adder, subtractor and parity checker of high-speed optical signals. Due to two-photon absorption in the wetting layer, quantum dot-semiconductor optical amplifier Mach-Zehnder interferometer (QD-SOA-MZI) can work as high data rate optical logic gates. The simulated result supports the idea that it is possible to realize all-optical binary adder, subtractor and parity checker at high optical signal rates.

Phase-locking-free all-optical matching system for 100 Gbaud QPSK optical signal.

Photonic firewall is a monitoring protection device that will directly detect and locate optical network attacks at the optical layer, which can effectively ensure the security of optical networks. An all-optical matching system is the core part of photonic firewall, which determines the performance of a photonic firewall, so it is of great significance to research and develop all-optical matching system for high-speed and high-order modulation formats signals. At present, an all-optical matching system for binary modulation formats is relatively mature, but the all-optical matching system for high-order phase modulation format signals is still limited by how to solve the problem of phase synchronization. In this paper, a new all-optical matching system based on self-interference matching is proposed for quadrature phase shift keying (QPSK) optical signal, which avoids the introduction of local target sequence optical signals and phase-locking circuits. The theoretical analysis and simulation verification are conducted for the designed system. The results demonstrate that the system can accurately identify and locate 4-symbol or 8-symbol target sequences in the input QPSK optical signals with 16-symbol and 32-symbol data sequences at a data rate of 100 Gbaud.

Method of field measurement of electromagnetic environment of high speed maglev train

Abstract In order to reduce the complexity of the magnetic field test of maglev trains and improve the accuracy of measurement data, this paper proposes a field measurement method of maglev train radiation emission based on high-speed parallel adaptive filter denoising technology. This measurement method is not limited by special measurement sites, and has the characteristics of high-speed measurement, real-time data processing, and large-capacity data storage. It breaks through the technical bottleneck of the traditional measurement system. The electromagnetic radiation emission of high-speed maglev trains is measured in real-time through multi-antenna synchronous measurement technology, and multi-channel high-speed RF signal measurement and acquisition of external signals are further carried out by blind source separation technology, environmental pre-scanning is carried out, environmental interference characteristics are obtained through feature statistics, and the radiation signal to be measured is estimated by blind source separation algorithm. It helps to achieve the purpose of accurately measuring the electromagnetic radiation emission of high-speed maglev trains. Through field testing, the denoising performance of the method reached 20 dB. Through field testing, the denoising performance of the method reached 20 dB.

Multiplier-less Broadband and Linear Phase Digital Hilbert Transformers

The Hilbert transformation for generating the analytic signal or signal envelope is widely used in modern communication receivers, in radar and sonar systems. It introduces a 90∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$90^{\\circ }$$\\end{document} phase shift of the input signal. Since the impulse response of the ideal Hilbert transformer is non-causal, it must be approximated by an FIR or IIR filter. This paper shows results of novel algorithms for designing broadband digital IIR Hilbert transformers and its implementation. The designs employ Galerkin or collocation techniques. The transfer function of the Hilbert transformer is a rational polynomial of low order and exhibits approximately linear phase. The filters match the 90∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$90^{\\circ }$$\\end{document} phase shift requirement of Hilbert transformers almost perfectly and exhibit approximately constant group delay in the passband. The achieved image rejection ratio is typically larger than 50 dB. The quantization of the filter coefficients is realized by a Canonical Signed Digit (CSD) representation, reducing the hardware resources compared with two’s complement. The resulting filters are multiplier-less, which is crucial for high-speed signal processing and low power consumption. The design techniques and the CSD representation are realized in a MATLAB toolbox. The filters were moreover implemented in VHDL and SystemC. Additionally, a MATLAB tool for automatically generating a VHDL package containing the filter parameters has been implemented.

Ultrastable 3D Heterogeneous Integration via N-Heterocyclic Carbene Self-Assembled Nanolayers.

The commercialization of 3D heterogeneous integration through hybrid bonding has accelerated, and accordingly, Cu-polymer bonding has gained significant attention as a means of overcoming the limitations of conventional Cu-SiO2 hybrid bonding, offering high compatibility with other fabrication processes. Polymers offer robust bonding strength and a low dielectric constant, enabling high-speed signal transmission with high reliability, but suffer from low thermomechanical stability. Thermomechanical stability of polymers was not achieved previously because of thermal degradation and unstable anchoring. To overcome these limitations, wafer-scale Cu-polymer bonding via N-heterocyclic carbene (NHC) nanolayers was presented for 3D heterogeneous integration, affording ultrastable packing density, crystallinity, and thermal properties. NHC nanolayers were deposited on copper electrodes via electrochemical deposition, and wafer-scale 3D heterogeneous integration was achieved by adhesive bonding at 170 °C for 1 min. Ultrastable conductivity and thermomechanical properties were observed by the spatial mapping of conductivity, work function, and force-distance curves. With regard to the characterization of NHC nanolayers, low-temperature bonding, robust corrosion inhibition, enhanced electrical conductivity, back-end-of-line process compatibility, and fabrication process reduction, NHC Cu/polymer bonding provides versatile advances in 3D heterogeneous integration, indicating that NHC Cu/polymer bonding can be utilized as a platform for future 3D vertical chip architectures.

A 25 Mbps 15 ns Propagation Delay 150 kV/μs CMTI Configurable Dual-Channel Capacitive Digital Isolation Driver.

Electrical isolation devices are essential components for safeguarding the reliability of electronic systems under harsh conditions. Digital isolators are widely used in low-power circuits due to their high immunity to disturbances. In this paper, a capacitive digital isolator for high-efficiency power supply scenarios is proposed with a high common-mode transient immunity (CMTI) and high data transmission rate. The on-off keying (OOK) modulation technique is used to ensure a high speed and accurate signal transmission. A fully integrated high-voltage level-shift driver with an ns-scale delay is proposed for increasing the drive capacity. Post-simulation results in Cadence IC 6.1.7 with the standard 0.18 μm CMOS process show that the proposed architecture achieves a 25 Mbps data transmission rate and 15 ns typical propagation delay with output peak currents of 2 A/4 A, respectively. Meanwhile, a CMTI of more than 150 kV/μs is realized.

Optically-reconfigurable integrated optical directed logic computing based on silicon photonics.

Optical directed logic, as a novel logical operation scheme, harmoniously combines the benefits of optical and electrical signals, surpassing traditional electrical and all-optical logic operations in terms of the flexibility and power consumption. Its potential in high-speed optical signal processing and electro-optical computing is immense. However, achieving tunability of the logic function normally relies on external electrical tuning or multiple laser sources, which often results in excessive power consumption and costs. In this work, by utilizing the polarization state of light within the optical directed logic, we demonstrate an optical directed logic device on a silicon-based platform. This single device can realize three different logic operations, which are XNOR, XOR and NAND, by simply changing the input light's polarization state, which comes at a minimal additional power consumption. Moreover, we also significantly enhance the device's response speed through a novel side-integrated metal thermal phase shifter, reducing the response time to 5 µs. Ultimately, we demonstrate logic operations at 60 kbps which maintains a leading standard among the currently reported thermally tuning optical-directed logic (ODL) devices, and successfully integrated polarization division multiplexing technique into ODL devices. This result provides a novel method to realize high-speed optical directed logic with high reconfigurability, which presents significant application prospects in the high-speed optical information processing field.

High Wideband Digital Oscilloscope Design

In most test applications, acquisition and analysis involving simultaneous processing of analog and digital signals. However, the bandwidth of most mainstream digital oscilloscopes is limited to 100 MHz, which is unable to meet the testing needs of high-frequency signals in complex electronic systems [1], and therefore, high-bandwidth digital oscilloscopes have emerged. Based on this background, this paper designs a digital oscilloscope hardware platform with high bandwidth by integrating FPGA and ARM technologies, aiming to meet the rigorous testing requirements of modern electronic systems. The FPGA module is based on the xc7s75fgga676 chip, which is mainly responsible for ADC control, data processing and frequency measurement functions. AM5708 is selected as the ARM module to realize the trigger, time base, amplitude and automatic setting functions of the oscilloscope. In order to ensure the accuracy and fidelity of waveform changes, the Sinc function interpolation method is used. This design further improves the acquisition bandwidth and processing speed on the basis of traditional MSO (Mixed Signal Oscilloscope) oscilloscopes, which is of great significance for the acquisition and processing of high-speed signals.

Hardware and Software Design of Programmable Medium and High-Speed Data Acquisition (DAQ) Board of Fiber Optic Signal for Partial Discharge Acquisition

The anti-electromagnetic interference capability of partial discharge (PD) acoustic signal conversion and collection circuits severely restrict the sensitivity of PD detection. The data acquisition (DAQ) systems available in the current market are costly and have limited functionality, making it difficult to satisfy the acquisition requirements for PD detection. This paper proposes a medium to high-speed fiber optic signal acquisition board with an adjustably controlled sampling rate and filter cutoff frequency. The circuit achieves a higher signal-to-noise (SNR) ratio by distributing the noise in each part of the signal acquisition chain reasonably. The temperature characteristics of the acquisition module are improved by utilizing the programmable T-type structure for transimpedance amplification of photocurrent. The DAQ card performs data acquisition and processing using STM32H743 internal ADC and caches data in bulk with an SRAM and SD card. A data uploading method based on time reference has been proposed, which enables full, effective information signal upload through a low-cost transmission interface. The research ultimately achieves a stable sampling of three channels at 1 MSps, SNR of 63 dB, and programmable gain amplification of the photocurrent with 0–60 dB. Finally, the system is used for PD acoustic signal acquisition in the frequency range of 20 Hz to 100 kHz.

Physical Compensation Approach for Feature Enhancement of High-Speed MFL Signals via Magnetic Field Polarization

Physical Compensation Approach for Feature Enhancement of High-Speed MFL Signals via Magnetic Field Polarization

Development of a high-performance arithmetic and logic unit for efficient digital signal processing based on reversible logic and quantum dots

Digital Signal Processing (DSP) finds a wide range of applications in various fields, including telecommunications, audio and video processing, biomedical engineering, radar systems, and image processing. Previous DSP designs faced limitations in available processing power and computational resources. Insufficient processing power could result in slower execution times, an inability to handle complex algorithms, or limited capacity to process high-speed or large-scale signals. As the demand for minimal power consumption in DSP circuits continues to grow, reversible logic and quantum-dot cellular automata (QCA) have emerged as promising technologies due to their inherent ability to reduce energy loss. Within this landscape, the arithmetic and logic unit (ALU) plays a vital role in complex circuitry, serving as a key component in digital signal processing applications. However, challenges persist, including high quantum cost and the need to limit the number of cells in the ALU design. To address these challenges, our research aims to develop an efficient ALU by integrating reversible logic and QCA technology. Our focus will be on generating essential components, such as Feynman gates, Fredkin gates, and full adder circuits, which serve as foundational building blocks for reversible logic and QCA designs. These components will be combined to construct a comprehensive ALU capable of performing 20 different operations. Our implementation efforts will be centered around QCADesigner, with a specific emphasis on digital signal processing systems that prioritize energy efficiency and optimal utilization of occupied areas.