Chip Design of a Low-Voltage Wideband Continuous-Time Sigma-Delta Modulator with DWA Technology for WiMAX Applications

This paper presents the design and experimental results of a continuous-time (CT) sigma-delta (ΣΔ) modulator with data-weighted average (DWA) technology for WiMAX applications. The proposed modulator comprises a third-order active RC loop filter, internal quantizer operating at 160 MHz and three DAC circuits. A multi-bit quantizer is used to increase resolution and multi-bit non-return-to-zero (NRZ) DACs are adopted to reduce clock jitter sensitivity. The NRZ DAC circuits with quantizer excess loop delay compensation are set to be half the sampling period of the quantizer for increasing modulator stability. A dynamic element matching (DEM) technique is applied to multi-bit ΣΔ modulators to improve the nonlinearity of the internal DAC. This approach translates the harmonic distortion components of a nonideal DAC in the feedback loop of a ΣΔ modulator to high-frequency components. Capacitor tuning is utilized to overcome loop coefficient shifts due to process variations. The DWA technique is used for reducing DAC noise due to component mismatches. The prototype is implemented in TSMC 0.18 um CMOS process. Experimental results show that the ΣΔ modulator achieves 54-dB dynamic range, 51-dB SNR, and 48-dB SNDR over a 10-MHz signal bandwidth with an oversampling ratio (OSR) of 8, while dissipating 19.8 mW from a 1.2-V supply. Including pads, the chip area is 1.156 mm2.

A Novel Full Differential Feedforward Fourth-Order Bandpass Sigma-Delta Modulator

In this paper,in order to reduce power consumption and chip area,as well as to improve the performance of the bandpass sigma-delta modulator,a novel full differential feedforward fourth-order bandpass sigma-delta modulator was proposed. It used a resonator based on Salo architecture,which employed doublesampling and double-delay technique. The results show that the proposed modulator can achieve lower power consumption and a lower capacitive load than the conventional bandpass modulators on the platform of Simulink. The circuit is implemented with TSMC0. 18 μm CMOS process and operates at a sampling frequency of 20 MHz, 80 MHz effective sampling frequency. Furthermore,it consumes 21. 2 mW from a 1. 8 V supply. The simulated peak signal-to-noise ratio( SNR) is 85. 9 dB and the dynamic range( DR) is 91 dB with 200 kHz bandwidth.

Disturbance Observer Design with a Bode’s Ideal Filter for Sigma-Delta Modulators

It is usually difficult to design a high performance Sigma⁃Delta(ΣΔ)modulator due to system noises.In this paper,a disturbance observer(DOB)is utilized to estimate the system noises and eliminate their effects on ΣΔ modulators.The applied DOB is introduced with a Bode's ideal cut⁃off(BICO)filter used for the Q⁃filter.The proposed DOB with the BICO filter used in ΣΔ modulators can achieve better noise⁃shaping ability,resulting from the less phase loss of the BICO filter.Finally,the simulation results show that the proposed BICO filter scheme is a useful additional tool for improving the performance of ΣΔ modulators.

COMPARISON OF SIGMA-DELTA MODULATOR FOR FRACTIONAL-N PLL FREQUENCY SYNTHESIZER

This paper investigates the design of digital Sigma-Delta Modulator (SDM) for fractional-N frequency synthesizer. Characteristics of SDMs are compared through theory analysis and simulation. The curve of maximum-loop-bandwidth vs. maximum-phase-noise is suggested to be a new criterion to the performance of SDM,which greatly helps designers to select an appropriate SDM structure to meet their real application requirements and to reduce the cost as low as possible. A low-spur 3-order Mul-tistage Noise Shaping (MASH)-1-1-1 SDM using three 2-bit first-order cascaded modulators is proposed,which balances the requirements of tone-free and maximum operation frequency.

Influence of substrate effect on near-field radiative modulator based on biaxial hyperbolic materials

Relative rotation between the emitter and receiver could effectively modulate the near-field radiative heat transfer(NFRHT)in anisotropic media.Due to the strong in-plane anisotropy,natural hyperbolic materials can be used to construct near-field radiative modulators with excellent modulation effects.However,in practical applications,natural hyperbolic materials need to be deposited on the substrate,and the influence of substrate on modulation effect has not been studied yet.In this work,we investigate the influence of substrate effect on near-field radiative modulator based onα-MoO_(3).The results show that compared to the situation without a substrate,the presence of both lossless and lossy substrate will reduce the modulation contrast(MC)for different film thicknesses.When the real or imaginary component of the substrate permittivity increases,the mismatch of hyperbolic phonon polaritons(HPPs)weakens,resulting in a reduction in MC.By reducing the real and imaginary components of substrate permittivity,the MC can be significantly improved,reaching 4.64 forε_(s)=3 at t=10 nm.This work indicates that choosing a substrate with a smaller permittivity helps to achieve a better modulation effect,and provides guidance for the application of natural hyperbolic materials in the near-field radiative modulator.

An improved single-loop sigma-delta modulator for GSM applications

Traditional feedforward structures suffer from performance constraints caused by the complex adder before quantizer.This paper presents an improved 4th-order 1 -bit sigma-delta modulator which has a simple adder and delayed input feedforward to relax timing constraints and implement low-distortion.The modulator was fabricated in a 0.35μm CMOS process,and it achieved 92.8 dB SNDR and 101 dB DR with a signal bandwidth of 100 kHz dissipating 8.6 mW power from a 3.3-V supply.The performance satisfies the requirements of a GSM system.

A 100-MHz bandpass sigma-delta modulator with a 75-dB dynamic range for IF receivers

A fourth-order switched-capacitor bandpass ∑△ modulator is presented for digital intermediatefrequency （IF） receivers. The circuit operates at a sampling frequency of 100 MHz. The transfer function of the resonator considering nonidealities of the operational amplifier is proposed so as to optimize the performance of resonators. The modulator is implemented in a 0.13-μm standard CMOS process. The measurement shows that the signal-to-noise-and-distortion ratio and dynamic range achieve 68 dB and 75 dB, respectively, over a bandwidth of 200 kHz centered at 25 MHz, and the power dissipation is 8.2 mW at a 1.2 V supply.

Broadband all-fiber optical phase modulator based on photo-thermal effect in a gas-filled hollow-core fiber

We report broadband all-fiber optical phase modulation based on the photo-thermal effect in a gas-filled hollow-core fiber.The phase modulation dynamics are studied by multi-physics simulation.A phase modulator is fabricated using a 5.6-cm-long anti-resonant hollow-core fiber with pure acetylene filling.It has a half-wave optical power of 289 mW at 100 kHz and an average insertion loss 0.6 dB over a broad wavelength range from 1450 to 1650 nm.The rise and fall time constants are 3.5 and 3.7μs,respectively,2–3 orders of magnitude better than the previously reported microfiber-based photo-thermal phase modulators.The gas-filled hollow-core waveguide configuration is promising for optical phase modulation from ultraviolet to mid-infrared which is challenging to achieve with solid optical fibers.

A 1-V 60-μW 85-dB dynamic range continuous-time third-order sigma-delta modulator

A 1-V third order one-bit continuous-time（CT） EA modulator is presented. Designed in the SMIC mixedsignal 0.13-μm CMOS process, the modulator utilizes active RC integrators to implement the loop filter. An efficient circuit design methodology for the CT ZA modulator is proposed and verified. Low power dissipation is achieved through the use of two-stage class A/AB amplifiers. The presented modulator achieves 81.4-dB SNDR and 85-dB dynamic range in a 20-kHz bandwidth with an over sampling ratio of 128. The total power consumption of the modulator is only 60 μW from a 1-V power supply and the prototype occupies an active area of 0.12 mm^2.

A review of liquid crystal spatial light modulators:devices and applications

Spatial light modulators,as dynamic flat-panel optical devices,have witnessed rapid development over the past two decades,concomitant with the advancements in micro-and opto-electronic integration technology.In particular,liquid-crystal spatial light modulator(LC-SLM)technologies have been regarded as versatile tools for generating arbitrary optical fields and tailoring all degrees of freedom beyond just phase and amplitude.These devices have gained significant interest in the nascent field of structured light in space and time,facilitated by their ease of use and real-time light manipulation,fueling both fundamental research and practical applications.Here we provide an overview of the key working principles of LC-SLMs and review the significant progress made to date in their deployment for various applications,covering topics as diverse as beam shaping and steering,holography,optical trapping and tweezers,measurement,wavefront coding,optical vortex,and quantum optics.Finally,we conclude with an outlook on the potential opportunities and technical challenges in this rapidly developing field.

Unveiling the biological role of sphingosine-1-phosphate receptor modulators in inflammatory bowel diseases

Inflammatory bowel disease(IBD)is chronic inflammation of the gastrointestinal tract that has a high epidemiological prevalence worldwide.The increasing disease burden worldwide,lack of response to current biologic therapeutics,and treatment-related immunogenicity have led to major concerns regarding the clinical management of IBD patients and treatment efficacy.Understanding disease pathogenesis and disease-related molecular mechanisms is the most important goal in developing new and effective therapeutics.Sphingosine-1-phosphate(S1P)receptor(S1PR)modulators form a class of oral small molecule drugs currently in clinical development for IBD have shown promising effects on disease improvement.S1P is a sphingosine-derived phospholipid that acts by binding to its receptor S1PR and is involved in the regulation of several biological processes including cell survival,differentiation,migration,proliferation,immune response,and lymphocyte trafficking.T lymphocytes play an important role in regulating inflammatory responses.In inflamed IBD tissue,an imbalance between T helper(Th)and regulatory T lymphocytes and Th cytokine levels was found.The S1P/S1PR signaling axis and metabolism have been linked to inflammatory responses in IBD.S1P modulators targeting S1PRs and S1P metabolism have been developed and shown to regulate inflammatory responses by affecting lymphocyte trafficking,lymphocyte number,lymphocyte activity,cytokine production,and contributing to gut barrier function.

A Novel Multiple DBC-staked units Package to Parallel More Chips for SiC Power Module

Silicon carbide(SiC) power modules play an essential role in the electric vehicle drive system. To improve their performance, reduce their size, and increase production efficiency, this paper proposes a multiple staked direct bonded copper(DBC) unit based power module packaging method to parallel more chips. This method utilizes mutual inductance cancellation effect to reduce parasitic inductance. Because the conduction area in the new package is doubled, the overall area of power module can be reduced. Entire power module is divided into smaller units to enhance manufacture yield, and improve design freedom. This paper provides a detailed design, analysis and fabrication procedure for the proposed package structure. Additionally, this paper offers several feasible solutions for the connection between power terminals and DBC untis. With the structure, 18dies were paralleled for each phase-leg in a econodual size power module. Both simulation and double pulse test results demonstrate that, compared to conventional layouts, the proposed package method has 74.8% smaller parasitic inductance and 34.9% lower footprint.

Waveguide-integrated optical modulators with two-dimensional materials

Waveguide-integrated optical modulators are indispensable for on-chip optical interconnects and optical computing.To cope with the ever-increasing amount of data being generated and consumed,ultrafast waveguide-integrated optical modulators with low energy consumption are highly demanded.In recent years,two-dimensional(2D)materials have attracted a lot of attention and have provided tremendous opportunities for the development of high-performance waveguide-integrated optical modulators because of their extraordinary optoelectronic properties and versatile compatibility.This paper reviews the state-of-the-art waveguide-integrated optical modulators with 2D materials,providing researchers with the developing trends in the field and allowing them to identify existing challenges and promising potential solutions.First,the concept and fundamental mechanisms of optical modulation with 2D materials are summarized.Second,a review of waveguide-integrated optical modulators employing electro-optic,all-optic,and thermo-optic effects is provided.Finally,the challenges and perspectives of waveguide-integrated modulators with 2D materials are discussed.

Multi-Objective Optimization Analysis of Auxiliary Flux Modulator Magnetic Gear with Unequal Magnetic Poles

To enhance the output torque and minimize the torque ripple of coaxial magnetic gear(CMG),a novel auxiliary flux modulator CMG with unequal magnetic poles is proposed.This design incorporates an inner rotor with an asymmetric sector and a trapezoidal combined N-S pole structure,featuring Halbach arrays for the arrangement of permanent magnets(PMs).The outer rotor PMs adopt a Spoke-type configuration.To optimize the CMG for high output torque and low torque ripple,a sensitivity analysis is conducted to identify key size parameters that significantly influence the optimization objectives.Based on the sensitivity hierarchy of these parameters,a multi-objective optimization analysis is performed using a genetic algorithm(GA)to determine the optimal structural parameter values of the CMG.In addition,a coaxial magnetic gear(CMG)topology with 4 inner and 17 outer pole pairs is adopted,and the parametric model is established.Finally,the electromagnetic properties of the CMG are evaluated using the finite element method.The results indicate a remarkable reduction in torque ripple,specifically by 46.15%.

一种高精度音频Sigma-Delta DAC的设计

设计了一种应用于音频Codec的高精度Sigma-Delta DAC,针对数字插值滤波器占用面积大的问题,提出了乘法器复用的方法,减少数字电路的硬件消耗。为解决Sigma-Delta调制器多比特量化引起的非线性问题,引入DWA(Data Weight Average)算法,提高系统的精度。此外,DCT(Direct Charge Transfer)电路用于实现数字域到模拟域的高精度转换。电路采用0.18μm CMOS工艺,整体DAC的信噪比为105.7dB@1150Hz,有效位数达到17.26bit。

高精度Sigma-Delta调制器设计

近年来,在过采样型模数转换器中,Sigma-Delta模数转换器以其较高的精度成为模数转换器的热点。介绍了一种高精度低功耗的Sigma-Delta调制器设计。使用Matlab工具完成三阶一位量化CIFF结构的系统仿真,在系统级仿真结果的指导下,积分器采用分级结构优化电路结构。积分器电路模块设计采用了全差分式开关电容电路,抑制了谐波失真对输出精度的影响。仿真结果显示:5 S/s挡位时,对应的PVT组合中最低有效位数为17.67 bits;2 kS/s挡位时,对应的PVT组合中最低有效位数为15.89 bits,整个调制器功耗低于3 mW。通过改进调制器整体架构、积分器结构和量化器的设计方法,降低了调制器功耗,提升了调制器精度。

Hypertrophic Scar Formation and Wound Healing Modulation Fatty Acids as Modulators of Severe Scars

Scar tissue usually generates severe discomfort in the short and long term. Common symptoms include anesthetics sequelae, pruritus, joint malfunction, new wounds on the scar surface, and pain. There are several treatments for scars, like compression, topical or intralesional steroid infiltration, 5-fluorouracil, dermabrasion, and surgeries with new scar tissue. For adult patients, it is easier to choose the treatment. However, compression is commonly applied in children to prevent treatments that have adverse effects. This study reports the outcomes of 15 patients submitted to abdominoplasty, traumatic wounds and post-burn scar treatments, which showed significant changes after the continuous use of an ointment composed of petrolatum, cod liver oil, BHT, Chamomilla recutita (chamomile) oil, Helianthus annuus (sunflower) oil, and Prunus amygdalus dulcis (sweet almond) oil. As components of the stratum corneum, unsaturated fatty acids influence the cutaneous structural and immune status and permeability. They also interfere with the maturation and differentiation of the stratum corneum and inhibit the production of proinflammatory eicosanoids, reactive species (ROS and RNS), and cytokines, thereby influencing the inflammatory response and possibly wound healing. This article aims to share our experience with the regular use of an ointment in adult and pediatric patients for three months. The increase in proinflammatory cytokine production at wound sites, resulting in a noninvasive, therapeutical, and effective cutaneous wound healing and scarring modulation, may provide a physiopathological explanation for the fast improvement of scars.

Design of Protograph LDPC-Coded MIMO-VLC Systems with Generalized Spatial Modulation

This paper investigates the bit-interleaved coded generalized spatial modulation(BICGSM) with iterative decoding(BICGSM-ID) for multiple-input multiple-output(MIMO) visible light communications(VLC). In the BICGSM-ID scheme, the information bits conveyed by the signal-domain(SiD) symbols and the spatial-domain(SpD) light emitting diode(LED)-index patterns are coded by a protograph low-density parity-check(P-LDPC) code. Specifically, we propose a signal-domain symbol expanding and re-allocating(SSER) method for constructing a type of novel generalized spatial modulation(GSM) constellations, referred to as SSERGSM constellations, so as to boost the performance of the BICGSM-ID MIMO-VLC systems.Moreover, by applying a modified PEXIT(MPEXIT) algorithm, we further design a family of rate-compatible P-LDPC codes, referred to as enhanced accumulate-repeat-accumulate(EARA) codes,which possess both excellent decoding thresholds and linear-minimum-distance-growth property. Both analysis and simulation results illustrate that the proposed SSERGSM constellations and P-LDPC codes can remarkably improve the convergence and decoding performance of MIMO-VLC systems. Therefore, the proposed P-LDPC-coded SSERGSM-mapped BICGSMID configuration is envisioned as a promising transmission solution to satisfy the high-throughput requirement of MIMO-VLC applications.

High photoelectric conversion efficiency and fast relaxation time of FA_(0.4)MA_(0.6)PbI_(3) applied in ultrafast modulation of terahertz waves

Active control of terahertz(THz)waves is attracting tremendous attentions in terahertz communications and active photonic devices.Perovskite,due to its excellent photoelectric conversion performance and simple manufacturing process,has emerged as a promising candidate for optoelectronic applications.However,the exploration of perovskites in optically controlled THz modulators is still limited.In this work,the photoelectric properties and carrier dynamics of FA_(0.4)MA_(0.6)PbI_(3)perovskite films were investigated by optical pumped terahertz probe(OPTP)system.The ultrafast carrier dynamics reveal that FA_(0.4)MA_(0.6)PbI_(3)thin film exhibits rapid switching and relaxation time within picosecond level,suggesting that FA_(0.4)MA_(0.6)PbI_(3)is an ideal candidate for active THz devices with ultrafast response.Furthermore,as a proof of concept,a FA_(0.4)MA_(0.6)PbI_(3)-based metadevice with integrating plasma-induced transparency(PIT)effect was fabricated to achieve ultrafast modulation of THz wave.The experimental results demonstrated that the switching time of FA_(0.4)MA_(0.6)PbI_(3)-based THz modulator is near to 3.5 ps,and the threshold of optical pump is as low as 12.7μJ cm^(-2).The simulation results attribute the mechanism of ultrafast THz modulation to photo-induced free carriers in the FA_(0.4)MA_(0.6)PbI_(3)layer,which progressively shorten the capacitive gap of PIT resonator.This study not only illuminates the potential of FA_(0.4)MA_(0.6)PbI_(3)in THz modulation,but also contributes to the field of ultrafast photonic devices.

Enhancing quantum temporal steering via frequency modulation

Various strategies have been proposed to harness and protect space-like quantum correlations in different models under decoherence.However,little attention has been given to temporal-like correlations,such as quantum temporal steering(TS),in this context.In this work,we investigate TS in a frequency-modulated two-level system coupled to a zero-temperature reservoir in both the weak and strong coupling regimes.We analyze the impact of various frequency-modulated parameters on the behavior of TS and non-Markovian.The results demonstrate that appropriate frequency-modulated parameters can enhance the TS of the two-level system,regardless of whether the system is experiencing Markovian or non-Markovian dynamics.Furthermore,a suitable ratio between modulation strength and frequency(i.e.,all zeroes of the 0th Bessel function J_(0)(δ/?))can significantly enhance TS in the strong coupling regime.These findings indicate that efficient and effective manipulation of quantum TS can be achieved through a frequency-modulated approach.