Effective crosstalk isolation through p+ Si substrateswith semi-insulating porous Si

Through-the-wafer porous Si (PS) trenches have been used to provide radio frequency (RF) isolation in Si because of their semi-insulating property. Reduction of crosstalk by 70 dB at 2 GHz and 45 dB at 8 GRz is demonstrated between Al pads with 800 μm separation on p⁺Si. Crosstalk suppression increases linearly with increasing PS width to beyond 320 μm. This suppression is degraded by one order of magnitude when the Si underneath the PS trenches remains and serves as a residual path for crosstalk. These results show that PS is an excellent candidate for RF isolation in modern VLSI technology     

Crosstalk Analysis of a Fiber Laser Sensor Array System Based on Digital Phase-Generated Carrier Scheme

A detailed study on analyzing the crosstalk in a wavelength division multiplexed fiber laser sensor array system based on a digital phase generated carrier interferometric interrogation scheme is reported. The crosstalk effects induced by the limited optical channel isolation of a dense wavelength division demultiplexer (DWDM) are presented, and the necessary channel isolation to keep the crosstalk negligible to the output signal was calculated via Bessel function expansion and demonstrated by a two serial fiber laser sensors system. Finally, a three-element fiber laser sensor array system with a 50-dB channel-isolation DWDM was built up. Experimental results demonstrated that there was no measurable crosstalk between the output channels.     

Three-dimensional substrate impedance engineering based on p/sup -//p/sup +/ Si substrate for mixed-signal system-on-chip (SoC)

A novel approach for three-dimensional substrate impedance engineering of p/sup -//p/sup +/ Si substrate is described for mixed-signal integrated circuit applications. This technology requires minimum intrusion to conventional Si CMOS processing, but offers astounding improvements with regard to radio frequency (RF) crosstalk via substrate and on-chip inductor performance. Electroless plating or electro-plating is used to fabricate Faraday cage for crosstalk isolation as well as to provide "true ground" contacts. A self-limiting porous Si (PS) formation process is employed to allow the insertion of PS regions from the backside of the wafer, eliminating completely the waste of chip surface area. On-chip inductors are situated above the semi-insulating PS regions allowing for greatly increased Q-factor and resonance frequency (f/sub r/). RF crosstalk is reduced to the level limited by that across the air gap between the measurement probes.     

Practical limits for optical test of spatial resolution in advanced imaging devices

Decreasing pixel size, perfection of isolation, and improved dynamic range of advanced imaging devices requires an adequate optical arrangement to check crosstalk behavior within the pixel matrix. The Fraunhofer diffraction pattern; an inherent feature of any focused circular beam, leads to unintended direct illumination of the neighbors even if accurately centered. A Simple setup has been applied to determine the beam profile focused down to the subwavelength range. We propose to characterize the beam focusing for spatial resolution tests by the first zero to-zero width independent of peak intensity. We provide an estimate of minimum requirements to be fulfilled in order to test for a given crosstalk and demonstrate their importance on filled trench-isolated pixels.     

V型人工电源网络寄生效应MATLAB仿真研究

运用MATLAB仿真软件分析了分立元件各寄生参数对分压系数、隔离度、串扰及阻抗的影响。通过分析接地和金属板的两种基本串扰形式,建立了人工电源网络（AMN）相应的等效电路模型,并用MATLAB仿真软件分析了两种模型下的寄生参数对AMN隔离度、阻抗的影响。结果表明：寄生参数及其耦合关系对AMN测量有较大影响。     

The importance of distributed grounding in combination with porous Si trenches for the reduction of RF crosstalk through p/sup -/ Si substrate

Locally incorporated porous Si (PS) trenches are used for radio frequency (RF) crosstalk isolation through p/sup -/ Si substrates. PS trenches provide large dielectric separation (large impedance) between the noise producing and the noise sensitive circuits without prohibitively high stress from a thermal expansion coefficient mismatch between bulk Si and the common dielectrics, e.g. SiO/sub 2/ and Si/sub 3/N/sub 4/. A variety of commonly used RF isolation structures are fabricated and compared. The best isolation structure for the p/sup $/substrates is shown to be the one with p/sup +/ grounding stripes in addition to a PS trench. Crosstalk between Al pads with 800 /spl mu/m separation is reduced to the level comparable to that through air. It is shown that contrary to our previous result using PS trenches in p/sup +/ substrates, p/sup +/ grounding stripes or PS trenches alone is quite ineffective. Superior RF isolation is achieved only when the two approaches are used in conjunction with one another. The combined approach results in additional crosstalk reduction of 21 dB at 2 GHz and 11 dB at 20 GHz.     

A rib optical waveguide with cutoff mesa isolation

A rib optical waveguide using the concept of optical cutoff to provide isolation between adjacent waveguides in a photonic integrated circuit is disclosed. Due to the evanescent nature of light propagation in cutoff waveguides, this cutoff mesa rib waveguide permits fabrication of single-moded rib waveguides with minimal self-interference and crosstalk by means of light guided in a remaining slab waveguide. Design rules are given and operation of a single-moded cut-off mesa rib waveguide and an MZI using this waveguide are demonstrated     

A New Approach to Optical Crosstalk Modeling in Single-Photon Avalanche Diodes

One of the main drawbacks of single-photon avalanche diode arrays is optical crosstalk between adjacent detectors. In the past, this phenomenon was basically ascribed to light propagating from one detector to another through a direct optical path. Accordingly, deep trenches coated with metal were introduced as optical isolation barriers between pixels. This solution, however, was unable to completely prevent the crosstalk. In this letter, we demonstrate that a strong contribution to optical crosstalk comes from photons reflected at the bottom of the chip. These photons can bypass trenches making them less effective.     

25-channel nematic liquid-crystal optical time-delay unitcharacterization

A 25-channel, 1-bit, free-space, nematic liquid crystal (NLCU) spatial light modulator (SLM)-based optical time delay unit (OTDU) is demonstrated with worst case electrical signal-to-noise ratios (SNR's) ranging from 50-60 dB for various delay/no-delay modes of operation and with a worst case -42,3-dB electrical channel isolation/crosstalk level. For comparison, single channel performance neglecting crosstalk noise but including within-channel leakage noise gives electrical SNR's from 74-85 dB, indicating that the leakage signal in this OTDU is minimal compared to crosstalk, To lower crosstalk, path-difference compensated imaging optics must be used by the OTDU     

Adjustable crosstalk and blooming suppression in imaging devices

Optical and electrical crosstalk performance of pixels in an integrated p-i-n photocapacitor matrix using RIE grooving of epitaxial Si wafers for isolations has been analyzed. Filled deep trench isolation in the optical devices not only resulted in superior crosstalk and blooming suppression as compared to reported conventional techniques but also provides a practical way for independent control of these effects in integrated one- or two-dimensional imaging arrays.     

Crosstalk in a fibre access network demonstrator carryingtelevision and interactive digital services

An optical access network is being constructed as part of the RACE programme to demonstrate the feasibility of providing both interactive broadband and television distribution services over a single, shared fibre to a residential subscriber. The interactive and distributive services will be transmitted in the 1.3 μm and 1.5 μm optical windows, respectively, of the fibre. To prevent crosstalk between the two services a wavelength division demultiplexer which gives adequate isolation between the two optical carriers must be provided at the subscriber receiver. Performance deterioration due to mutual crosstalk is calculated and measurement results presented. Theory and measurement show that the deterioration of the interactive signal caused by the distributive signal sets the most demanding isolation requirement. For an interactive signal penalty of 0.5 dB the isolation has to be 40 dB, which is at the limit of the performance achieved by commercially available wavelength division demultiplexers     

串扰对WDM光网络功率管理的影响

提出了一种新的节点功率管理方案,即同时考虑同频串扰和自发辐射噪声的总功率管理,针对两种节点隔离原则,给出了其数学模型,并进行了仿真计算,结果表明同频串扰对WDM光网络的规模和光信号的质量都有着重要的影响,而监测点的选取对信号质量影响不大。     

Crosstalk reduction in mixed-signal 3-D integrated circuits with interdevice layer ground planes

We show nearly 8 dB of crosstalk reduction using ground planes between active device layers in three-dimensional (3-D) integrated circuits. Our experimental work utilizes two planes of MOS transistors with tungsten or polysilicon ground planes designed to attenuate crosstalk. Theoretical simulations, using an electromagnetic solver, and the experimental results are consistent with analytical results. The key result verified is that a ground plane, whose footprint shadows the device area, is sufficiently large for effective attenuation. The interdevice layer ground plane provides an effective means to achieve crosstalk reduction in 3-D mixed-signal/RF integration because of simple fabrication and high coupling isolation.     

Influence of EDFA''''s Characteristics on Performance of All Optical Network

The characteristic of EDFA in WDM system is analyzed. The simulation system based on the architecture of the China Information Network (CAINONET) is introduced, and the influence of noise figure, gain unflatness and output power of EDFA on the BER performance and scale of network is investigated. Moreover, the influence of noise figure is studied with different crosstalk . Meanwhile, it is indicated that it is important to apply the "node isolation principle" in the optical network. The research results can provide the valuable reference for the practical construction of all optical network .     

Effective Crosstalk Isolation With Post-CMOS Selectively Grown Porous Silicon Technique for Radio Frequency System-on-Chip (SOC) Applications

In this letter, post-CMOS substrate selective-transformation engineering based on the selectively grown porous silicon (SGPS) technique is demonstrated to effectively suppress substrate crosstalk. The testing structures for crosstalk isolation are fabricated in a standard 0.18-$muhbox{m}$ CMOS process, and porous silicon trenches are selectively grown after processing from the backside of the silicon wafer. For a testing structure with 250-$muhbox{m}$ separation on Si, a 42.8-dB improvement (from $-$23.5 to $-$66.3 dB) for crosstalk isolation is achieved at 2 GHz. The characteristics of the SGPS substrate have been extracted using the conventional lump element model, which shows that our SGPS technique increases the substrate impedance by one order of magnitude. These results demonstrate that our post-CMOS substrate selective-transformation engineering is very promising for radio frequency system-on-chip applications.      

Monolithic GaInAs/InP photodetector arrays for high-densitywavelength division multiplexing (HDWDM)

Monolithic arrays of interdigitated GaInAs/InP photodetectors have been fabricated for high density wavelength division multiplexing (HDWDM) applications. The detectors typically exhibit a reverse leakage current of 400 nA, capacitance of less than 70 fF and a responsivity of 0.5 A/W at -5 V bias. An optical crosstalk of -33.4 dB has been measured between adjacent detectors in an experimental grating demultiplexer system. Preliminary electrical crosstalk measurements in the frequency range of 1-500 MHz indicate signal isolation of the order of 46 dB     

Scaling and Pixel Crosstalk Considerations for CMOS Image Sensor

With the scaling development of the minimum lithographic size, the scaling trend of CMOS imager pixel size and fill factor has been computed according to the Moore rule. When the CMOS minimum lithographic feature scales down to 0.35 μm,the CCD imagepixel size is not so easy to be reduced and but the CMOS image pixel size benefits from the scaling minimum lithographic feature. However, when the CMOS technology is downscaled to or under 0.35μm,the fabrication of CMOS image sensors will be limited by the standard CMOS process in both ways of shallow trench isolation and source/drain junction, which results in pixel crosstalk. The impact of the crosstalk on the active pixel CMOS image sensor is analyzed based on the technology scaling. Some suppressed crosstalk methods have been reviewed. The best way is that combining the advantages of CMOS and SOI technology to fabricate the image sensors will reduce the pixel crosstalk.     

Improved linear crosstalk tolerance in an un-amplified ring PON

There is increased interest in ring-based passive optical network (PON) architectures due to their local area network (LAN) capability among end users and inherent protection and restoration schemes. The ring architecture includes optical filters and switches with non-ideal channel isolation, leading to the generation of linear crosstalk, which can significantly degrade the system performance if it is not sufficiently suppressed. We use simulation to analyze the effects of linear crosstalk in an un-amplified TDM optical ring and show how we can improve the tolerance of the crosstalk in our architecture that employs optimized tap split ratios as a means of increasing the number of ONUs served. Our approach is based on simulation of the entire network using a combination of wavelength-domain and time-domain techniques. Typically, PON networks use two or three wavelengths that are separated by more than 50 nm to maintain the cost of components low and as such, it is logical that any crosstalk will be negligible. However, the subpar performance of such components motivated our study into the impact of crosstalk. We show that the tap ratio optimization which increases the number ONUs that can be served in the ring can also exacerbate the effects of linear interchannel crosstalk at the ONU’s downstream signal receivers. We also show that surplus power at the last ONU can be utilized to counter this degraded crosstalk performance by careful tap ratio selection, thereby improving the overall tolerance to linear crosstalk in the system.     

Dual-channel and multifrequency radar system calibration

Uncertainty in absolute gain and crosstalk factors are the primary sources of error in dual-channel radar measurements. A full two-port calibration technique compensates for the errors introduced due to an imperfect antenna system and improves the isolation between orthogonal polarization channels as long as the observed cross section is above the equivalent system noise cross section. A novel technique for calibrating a dual-polarized network analyzer-based scatterometer system is discussed. Rigorous two-port S-parameter representation is used to describe absolute gain and crosstalk characteristics. Validity of the crosstalk correction is demonstrated by measuring the point target scattering matrix. Correction factors are obtained by measuring the S-parameters of trihedral and dihedral corner reflectors of known sizes. Results of absolute gain of the antenna system are verified using independent test target cross section measurements     

Estimation of performance degradation of bidirectional WDM transmission systems due to Rayleigh backscattering and ASE noises using numerical and analytical models

We develop a numerical model for the transmission performance of bidirectional wavelength-division-multiplexed (WDM) transmissions. Using the numerical model, wavelength-interleaved 10-Gb/s bidirectional WDM systems are analyzed by considering the impairment of the system performance due to Rayleigh backscattering (RB). We also calculate the power penalty and the crosstalk due to RB from the analytical model, and then compare to the results obtained from the numerical model. The analytical model can provide similar results obtained from the numerical model. Both the numerical and analytical models suggest that the total isolation of filters must be more than 19.5 dB for 320-km transmission while keeping the power penalty of less than 2 dB.