Differential Transmission Lines Research Articles

Design and analysis of high-resolution CMOS digitally controlled oscillator with tunable transformer

A tunable transformer based millimeter-wave digitally controlled oscillator (DCO) is proposed to achieve high frequency resolution with compact area in this paper. An 8-shaped inductor is employed as primary coil of the transformer to generate the opposite magnetic field and achieve a weak coupling to the secondary coil, which is beneficial to enhance the scaling effect of the capacitor to achieve a smaller equivalent capacitance. The equivalent model of the transformer structure is analyzed theoretically. Distributed capacitors are placed under the secondary coil, which can be flexibly adjusted to achieve high frequency resolution. A digitally controlled artificial dielectric (DiCAD) differential transmission line is implemented to achieve coarse and medium frequency tuning. The DCO is implemented in 40-nm CMOS process with a core area of 0.026 mm2. Simulated results demonstrate a minimum frequency tuning step of 381 KHz with a frequency tuning range of 12.3% from 58.60 to 66.28 GHz, and the phase noise at 1-MHz offset is from −91.3 to −94.0 dBc/Hz, corresponding to an FoM range of −179.5 to −182.2 dB, while the power consumption is 8.8 mW.

A Compact Fully-Differential Distributed Amplifier with Coupled Inductors in 0.18-µm CMOS Technology

This paper presents a compact fully-differential distributed amplifier using a coupled inductor. Differential distributed amplifiers are widely required in optical communication systems. Most of the distributed amplifiers reported in the past are single-ended or pseudo-differential topologies. In addition, the differential distributed amplifiers require many inductors, which increases the silicon cost. In this study, we use differentially coupled inductors to reduce the chip area to less than half and eliminate the difficulties in layout design. The challenge in using coupled inductors is the capacitive parasitic coupling that degrades the flatness of frequency response. To address this challenge, the odd-mode image parameters of a differential artificial transmission line are derived using a simple loss-less model. Based on the analytical results, we optimize the dimensions of the inductor with the gradient descent algorithm to achieve accurate impedance matching and phase matching. The amplifier was fabricated in 0.18-μm CMOS technology. The core area of the amplifier is 0.27 mm2, which is 57% smaller than the previous work. Besides, we demonstrated a small group delay variation of ±2.7 ps thanks to the optimization. the amplifier successfully performed 30-Gbps NRZ and PAM4 transmissions with superior jitter performance. The proposed technique will promote the high-density integration of differential traveling wave devices.

Differential-to-Common-Mode Noise Conversion Suppression on Right-Angle-Bent Differential Transmission Lines Using 3D-Printed Dielectric Materials

A method using 3D-printed dielectric materials is proposed to suppress differential-to-common-mode noise conversion in right-angle-bent differential transmission lines. The permittivity of the 3D-printed dielectric material decreases the phase velocity of the shorter inner line of the differential transmission lines. Decreasing the phase velocity of the inner line enables the transmission line phase difference to approach 180°, suppressing differential-to-common-mode noise conversion. Simulation shows that increasing the length of the dielectric material causes a decrease in the phase velocity of the transmission line, suppressing differential-to-common-mode noise. The measured results agree with the simulation, indicating suppression in Scd21. The eye height of the eye diagram improved by 19.63%, improving the system signal integrity.

A New Method for Twisted Wire Crosstalk Estimation Based on GA-BP Neural Network Algorithm

Based on the research of genetic algorithm (GA) to optimize the BP neural network algorithm, this paper proposes a method for predicting twisted wire crosstalk based on the algorithm. Firstly, the equivalent circuit model of a multi-conductor transmission line is established, combined with the method of similarity transformation, the second-order differential transmission line equations are decoupled into n groups of independent two-conductor transmission line equations, and the crosstalk is finally solved. Then the mathematical model of the twisted wire is established and its structural characteristics are analyzed, and the GA-BP neural network algorithm is used to realize the mapping of the electromagnetic parameter matrix of the twisted wire and the position of the twisted wire. Finally, the mapping relationship is substituted into the transmission line equation, and the near-end crosstalk (NEXT) and the far-end crosstalk (FEXT) of an example three-core twisted wire are predicted based on the idea of cascade combined. By comparing with the transmission line matrix method (TLM), it can be seen that the method proposed in this paper is in good agreement with the crosstalk results obtained by the electromagnetic field numerical method, which verifies the effectiveness of the algorithm proposed in this paper.

A 19.1–25.5-GHz Compact Dual-Mode Rotary Traveling-Wave Oscillator With 195.4-dBc/Hz FoM

In this letter, a dual-mode rotary traveling-wave oscillator (RTWO) is proposed to achieve wide operation bandwidth and multiple phases. Two twisted differential transmission lines are coupled together to form the dual-mode traveling-wave resonator. Sixteen pairs of back-to-back inverters and capacitors are connected to the resonators to introduce the multicore multi-phase operation. The mode switches are used to control the coupling direction and select the desired mode without degrading the quality factor. Verified in a 40-nm CMOS process, the proposed dual-mode RTWO exhibits a dual-mode frequency range from 19.1 to 25.5 GHz with the core size of 0.08 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\textbf {2}}$ </tex-math></inline-formula> . The measured 10-MHz phase noise at 25.30 and 22.12 GHz is −129.6 and −131.5 dBc/Hz, respectively. The best FoM and FoMT are 186.2 and 195.4 dBc/Hz, respectively.

A K-Band CMOS Standing Wave Oscillator Using Digital-Controlled Artificial Dielectric Differential Transmission Lines

This letter presents a K-band standing wave oscillator (SWO) based on digital-controlled artificial dielectric differential transmission lines (DiCAD-DTLs). By combining the unique property of constant phase and digitally controlled wide tuning range, the proposed design achieves a better balance between phase noise and tuning range. A compact layout and high operating frequency are, hence, possible, since DiCAD-DTLs in this design behave like a resonator instead of a capacitor bank. This chip was fabricated in a standard 0.13- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> CMOS process with an area of 0.035 mm2. It achieves a tuning range from 19.2 to 21.6 GHz. The measured phase noise is around −104.7 dBc/Hz at a 1-MHz offset. This oscillator including buffer consumes 5 mA from a 1.5-V supply, demonstrating a figure of merit (FOM) and FOM <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm {_{T}}$ </tex-math></inline-formula> of −181.8 and −183.3 dBc/Hz, respectively.

Mode Conversion and Common-Mode Noise Reduction Using Periodic Structure Filter

In this article, a 90°-bent differential transmission line using the asymmetric periodic structure filter is proposed. The asymmetry of the periodic structure filter is used to reduce the differential-to-common mode conversion while the frequency response of the periodic structure filter is used to reflect the common-mode noise. As compared with the conventional 90°-bent differential transmission line, the differential-to-common mode conversion is greatly reduced from −3.04 to −20.42 dB while the time-domain differential-to-common mode transmission is greatly reduced from 0.094 to 0.006 V. Besides, the common-mode reflection coefficient is largely increased from −13.72 to −0.94 dB while the time-domain common-mode reflection is largely increased from 0.017 to 0.068 V. Furthermore, the performance of the eye diagram is upgraded, meaning that the signal integrity is improved.

Noise Countermeasure Effect of Common Mode Choke Coil on Electromagnetic Radiation Characteristics from Differential Transmission Line

Noise Countermeasure Effect of Common Mode Choke Coil on Electromagnetic Radiation Characteristics from Differential Transmission Line

Design and Analysis of a Novel Compact Metamaterial Absorber Based on Double-Layer ITO Resistive Film for Improving Signal Integrity

This paper presents a compact metamaterial absorber (MMA) based on double-layer ITO resistive film for suppression of electromagnetic interference (EMI) to improve signal quality and signal integrity (SI). In the design of MMA, based on the classic Jerusalem cross, circular and fan-shaped structures are combined to increase its equivalent capacitance to achieve frequency shift, and an equivalent circuit model is established to analyze the key factors affecting its absorption rate. At the same time, the full-wave simulation results show that more than 90&#x0025; absorption rate is achieved in the frequency range of 8.9 GHz-14.0 GHz, and the measurement results show that the absorption rate of MMA at different incident angles is consistent with the simulation. Moreover, microstrip antenna and differential microstrip transmission line are also designed as equivalent radiation sources. The co-simulation results show that the 3 m field radiation of the patch antenna is reduced by 10 <inline-formula> <tex-math notation="LaTeX">$dB\mu V$ </tex-math></inline-formula> at 10 GHz. At the same time, the eye height of the differential microstrip transmission line has increased from 68 mV to 340 mV, indicating that the signal integrity problem has been significantly improved. The size of the unit is only about 0.065 <inline-formula> <tex-math notation="LaTeX">$\lambda _{L}\times 0.065\,\,\lambda _{L}$ </tex-math></inline-formula> where <inline-formula> <tex-math notation="LaTeX">$\lambda _{L}$ </tex-math></inline-formula> is the wavelength of the lowest frequency, and the total thickness of the absorber is only 0.047 <inline-formula> <tex-math notation="LaTeX">$\lambda _{L}$ </tex-math></inline-formula>. The proposed MMA has the characteristics of miniaturization, ultra-wideband, high absorption rate, and polarization insensitivity, which provides a new suppression method for the radiation problem of gradually miniaturized electronic equipment.

Effect of intravalley and intervalley electron-hole exchange on the nonlinear optical response of monolayer MoSe2

The coherent third-order nonlinear response of monolayer transition-metal dichalcogenide semiconductors, such as ${\mathrm{MoSe}}_{2}$, is dominated by the nonlinear exciton response, as well as biexciton and trion resonances. The fact that these resonances may be spectrally close together makes identification of the signatures, for example in differential transmission (DT), challenging. Instead of focusing on explaining a given set of experimental data, a systematic study aimed at elucidating the roles of intravalley and intervalley long-range electron-hole $(e\ensuremath{-}\mathrm{h})$ exchange on the DT spectra is presented. Previous works have shown that the $e\ensuremath{-}\mathrm{h}$ long-range exchange introduces a linear leading-order term in the exciton dispersion. Based on a generalized Lippmann-Schwinger equation, we show that the presence of this linear dispersion term can reduce the biexciton binding energy to zero, contrary to the conventional situation of quadratic dispersion where an arbitrarily weak (well-behaved) attractive interaction always supports bound state(s). The effects of spin scattering and the spin-orbit interaction caused by $e\ensuremath{-}\mathrm{h}$ exchange are also clarified, and the DT line shape at the exciton and trion resonance is studied as a function of $e\ensuremath{-}\mathrm{h}$ exchange strength. In particular, as the exciton line shape is determined by the interplay of linear exciton susceptibility and the bound-state two-exciton resonance in the $T$ matrix, the line shape at the trion is similarly determined by the interplay of the linear trion susceptibility and the bound-state exciton-trion resonance in the $T$ matrix.

Built-in Ring Transmission Line Structure for Signal Integrity Optimization of PAM4 Signaling in PCBs

In this article, we propose a built-in ring differential transmission line for four-level pulse amplitude modulation (PAM4) signal integrity optimization. An optimized ring structure, which comes from the simplistic idea to leverage the voltage produced by near-end crosstalk inside the ring, is attached at the end of the transmission line to improve the eye diagram. Additionally, we introduce the comprehensive design guideline with analytically derived formulas that is beneficial to designers to obtain an accurate design without significant effort. The proposed structure is implemented on a 100 mm transmission line, six-layer printed circuit board. The proposed structure can achieve an improvement of up to 32.9% eye height with a 4 Gsps PAM4 signal.

Differential‐to‐single‐ended crossover based on dumbbell‐shaped defected ground resonators for dual‐band applications

This article presents a novel differential-to-single-ended (DS) crossover by using two rings included of controllable frequency ratio of composite right- and left-handed (CRLH) transmission lines for dual-band applications. To reject the out-of-band differential-mode transmission coefficient, two dumbbell-shaped defected ground resonators (DGRs) are utilized over the differential transmission lines. Theoretical analysis proves that the frequency ratio can be controlled by choosing the number of designing CRLH cells and the parameter values appropriately. Also, desired electrical lengths and impedances of DGRs were obtained at the bandstop notch of differential-mode transmission coefficient by conducting common- and differential-mode analysis of lumped element equivalent circuit. To validate the proposed structure, two fabricated prototypes including the DS crossover designing at 1.8 and 4.2 GHz and separate differential lines with embedded DGRs were fabricated and measured. Measurement mixed-mode results exhibit that the fabricated crossover has great results at both frequency bands and has a good out-of-band differential insertion loss rejection.

Method of suppressing noise in a differential transmission line using a near-field noise-suppression device

Method of suppressing noise in a differential transmission line using a near-field noise-suppression device

CST Analysis and Simulation of Signal Integrity of Differential Transmission Lines

The differential transmission line has been widely used in the field of high-speed signals with its unique transmission characteristics, and it will be affected by many factors during the transmission process. In this paper, the differential transmission line is taken as the research object, and a three-dimensional electromagnetic simulation software CST is used to study its signal integrity performance parameters including characteristic impedance, loss, and crosstalk. It is found through simulation that increasing the spacing between differential pairs will reduce the crosstalk. The smaller the differential pair length, the greater the value of the insertion loss. This will improve the quality of signal transmission.

Preface

Sincerely welcome you to 2020 2nd International Conference on Computer Modeling, Simulation and Algorithm (CMSA2020), which is supported by SERC Science and Engineering Research Center. With the progress of science and technology, the performance of computer modeling and simulation has been constantly improved, data acquisition has become more convenient and data analysis has greatly improved research efficiency. Growing researchers join in scientific research, and the increasing research interests also indicate that the prosperous period of Computer Modeling, Simulation and Algorithm research is coming.In this special period when the pneumonia epidemic still needs high attention, in order to respond to the epidemic prevention and control, and to ensure the safety of all participants to the greatest extent, CMSA2020 was conducted in the form of online cloud meeting on August 7, 2020. With meticulous arrangement of our conference staff and active cooperation of all the participants, we firmly believe that it is doomed to be a refreshing and effective mode of academic communication in the case of safety is guaranteed, from which all the participants surely benefit a lot.CMSA2020 was held through the ZOOM cloud meeting platform. Before the formal meeting, our staff set up test rooms for keynote speakers and author representatives respectively, mainly testing the video, audio, screen sharing and other operations. CMSA2020 was officially opening at 9:00am (Beijng Time) on August 7, 2020. This conference mainly adopted keynote speeches and oral presentations for academic research exchange, that is, specially invited experts gave a 40-minute keynote speech and each author gave a 10-15minute speech. After each presentation, we set a Q & A session of about 10-15 minutes, so that all authors can participate in it and get more research experience in the brainstorming.We invite Prof. Xueyan Lin and Prof. Kalyana C. Veluvolu to take part in CMSA2020 and make Keynote Speeches. Prof. Xueyan Lin from Beijing University of Posts and Telecommunications, China gave her keynote speech entitled CST Simulation and Analysis of Signal Integrity of Differential Transmission Lines. Prof. Kalyana C. Veluvolu from Kyungpook National University, South Korea made his keynote speech on Identification of Most Significant Brain Functional Networks with EEG. All participating authors also actively shared their latest academic achievements in Computational Modelling, Simulation and Its Application, Algorithm and Mathematics and related fields. This meeting was fast-paced, professional and efficient. All participants actively shared their academic achievements and extended more wonderful and interesting further researches during the Q & A session.We have authors from China, Spain, USA, Republic of Chile, Thailand, Colombia, Russia, Australia, France, Honduras, Australia, Romania and so on. We called for nearly a hundred professors with related research interests as Technical Program Committee members to maximize the quality and usability of this conference paper. We pursue high-quality academic papers by setting up strict reviewing mechanism and high standards of modification requirements all the time. According to main theme and topics, all article manuscripts are assigned to relevant experts for peer reviewing, and they mainly focus on the topic relevance, language standardization and originality. iThenticate Software matters lot in maintaining originality.According to the relevance of paper topics and on the basis of the suggestions of reviewers, CMSA2020 papers are divided into 5 sections: Computer Modeling and Simulation Technology; Applied Mathematics, Data Analysis and Data Mining; Advanced Algorithms, Analysis Model, Optimization Design and Its Application; Image Processing, Pattern Recognition and Artificial Intelligence and Communications and Intelligent Information System.On behalf of the organizing committee, I would like to express my sincere thanks to Journal of Physics: Conference Series for their accurate publication for CMSA2020 papers, involved reviewers and editors in Technical Program Committee for their time and energy in reviewing manuscripts and give professional comments. We will redouble our efforts to provide better and more perfect services for academic research and promote the development of computer modeling, simulation and algorithm. We truly hope for the future cooperation with you.CMSA2020 Organization Committees

Differential SIW slot antenna array with intrinsic common‐mode rejection

In this study, the differential substrate integrated waveguide (SIW) slot antenna array is proposed with intrinsic common-mode (CM) rejection. Through field analysis, it is found that the SIW is a natural differential transmission line which can only transmit differential signal due to the characteristics of hybrid electromagnetic boundary perfect electrical conductor and perfect magnetic conductor. Hence, it can also be seen as a natural balun with intrinsic CM suppression. Thus, a compact 1 × 4 differential SIW slot antenna array with high CM rejection can be designed using the differential microstrip transition structure which has little conversion between differential-mode (DM) and CM. For the design of differential SIW passive device, the DM equivalent half circuit is a single-ended SIW device with height halved. Further, the 4 × 4 differential SIW antenna array with high CM rejection can be designed with a T-shaped differential SIW four-way power divider. The 1 × 4 and 4 × 4 differential SIW antenna arrays are fabricated and good agreements between the simulated and measured results demonstrate the validity of proposed configurations.

Wideband Dual Circularly Polarized Antenna for Intelligent Transport Systems

A wideband dual circularly polarized (DCP) antenna is presented for intelligent transport system (ITS) applications, which can be used to improve the receiver sensitivity and communication quality of ITS. The presented DCP antenna is composed of an orthogonal power divider (OPD) with two orthogonal input ports, four phase shifters for quadrature phase output, and four crossed dipoles for DCP radiation. Detailed equivalent circuit analysis shows that the OPD has two orthogonal inputs and four equal magnitude in-phase and out-of-phase outputs. To achieve two sets of orthogonal quadrature output signals for DCP radiation, the lumped element based differential right-hand transmission line unit cell and left-hand transmission line unit cell are elaborately introduced as the ±45° phase shifters, and incorporated into the OPD. Eventually, orthogonal quadrature signals are successfully obtained and fed to the crossed dipoles for DCP radiation. The proposed antenna was then designed, fabricated, and measured for ITS applications. The measured results show that the overlapped impedance bandwidth of both two input ports is 1.07–1.85 GHz (53.4%), and the isolation is higher than 15.2 dB. Moreover, low axial ratio (<1.7 dB) and symmetrical radiation patterns are achieved for unidirectional DCP radiation.

Circuit Model of Parallel Corrugated Transmission Lines for Differential Signal Propagating in Microwave Band

A viable wide-band circuit model of parallel corrugated differential transmission line is established. By solving for the even- and odd-modes in this structured differential transmission line, the equivalent capacitance, inductance, resistance, and conductance per unit length are calculated, then the characteristic impedances of differential and common signals are obtained. The ${S}$ -parameters obtained from the equivalent circuit model agree well with the full-wave simulation results with a deviation of only about 0.036 dB in the frequency range of 10 GHz. Experimentally, the characteristic impedances are measured for the differential and common signals using a time domain reflectometer (TDR). The deviation between the experimental and theoretical results was less than 1.05%. Based on the equivalent circuit model, it is feasible to implement this type of structured differential line directly into real circuits.

High frequency common-mode noise in serdes circuits’ optimized interconnections

According to the requirements imposed by the new four-level pulse amplitude modulation (PAM4) standard for high-speed data transfer and processing, electrical constraints and manufacturing tolerances in integrated electronic packages impose accurate electromagnetic simulations and new S-parameters analysis, saving time and financial resources for next-generation switches, routers or data centers circuits implementation. The complexity of the advanced networking class circuits? encapsulation substrates massively increases due to the large number of differential signals that it integrates. Differential signaling has replaced single-ended transmission in high-speed circuits due to their many advantages, including increased immunity to crosstalk and electromagnetic interference, but common-mode noise due to timing skew or amplitude unbalance differences can still affect them. This work tests five different models, identifies and optimizes the 45? bends, structures that commonly affect the reflections in a differential stripline. Then it studies differential transmission lines in stripline topology, implemented in a 12-layered flip-chip package, using S-parameters, inspecting and comparing the common-mode noise. In this way, the paper combines microwave theory with a real chip packaging design in an innovative way, using finite element analysis of electromagnetic field simulation and mixed-mod scattering parameters of differential topologies, towards an optimized structure design.

Study of transmission-line impedance of strip lines in an MRPC detector

Characteristic impedance study of differential transmission lines based on Digital Sampling Oscilloscope is carried out, and more than 72 multi-gap resistive plate chambers (MRPC) with different structures have been developed and tested. The results show that the impedance is related to the overall electromagnetic field structure, which is determined by the number and width of gas gaps and glass, the number of stacks, and the width of signal strips. The equivalent dielectric constant of the dielectrics between the paired readout strips has been introduced and applied into Wheeler’s equations. After that, the outcome of the equations corresponds with the test results. In addition, a new approximate formula for calculating the transmission-line impedance of multi-stack MRPC detectors is proposed. The values computed from the formula show a good agreement with the experimental data, thus demonstrating its validity.