Modeling and analysis of QPSK/TDMA burst-mode link analyzer bycomputer simulation

The authors describe modeling and simulation of a nonlinear QPSK/TDMA (quadrature phase-shift keyed/time-division multiple access) digital satellite channel and burst-mode link analyzer (BMLA), using novel computational and least-squares (LS) approaches on a VAX 11/780 computer. The BMLA is applied to channel equalization. Some simulation results are given, including results on the BMLA with LS algorithm and on the effects of nonlinearity and quantization wordlength. Emphasis is placed on the introduction of the BMLA/LS to impulse response extraction, and on the comparison and evaluation of the test results, which confirm the possibility of the BMLA/LS applications in a digital communication channel and confirm this simulation system as a powerful tool for QPSK/TDMA link analysis and channel equalization     

A 1.25-gb/s burst-mode receiver for GPON applications

This paper presents a 1.25-Gb/s burst-mode receiver (BMRx) for upstream transmission over gigabit passive optical networks (G-PONs). The dc-coupled receiver uses a unique arrangement of three limiting amplifiers to convert the bursty input signal to a current mode logic output signal while rejecting the dc offset from a preceding transimpedance amplifier. Peak detectors extract a decision threshold from a sequence of 12 successive nonreturn-to-zero (NRZ) 1's and 12 successive NRZ 0's received at the beginning of each packet. Automatic compensation of the remaining offsets of the BMRx is performed digitally via digital-to-analog converters. The chip was designed in a 0.35-/spl mu/m SiGe BiCMOS process. The receiver contains an APD with a gain of 6 and a transimpedance amplifier and shows a sensitivity of -32.8 dBm and a dynamic range of 23.8 dB. A sensitivity penalty of 2.2 dB is incurred when a packet with average optical power of -9 dBm precedes the packet under consideration, the guard time between the packets being 25.6 ns. The BMRx includes activity detection circuitry, capable of quickly detecting average optical levels as low as -35.5 dBm. The performed measurements prove that the receiver meets the G-PON physical media dependent layer specification defined in ITU-T Recommendation G.984.2.     

A complete 400-Mb/s burst-mode data OEIC receiver

A fully integrated burst-mode GaAs MESFET optoelectronic integrated circuit (OEIC) receiver, 215 mil×109 mil, that has been designed and implemented for point-to-point data links for application as a phased-array antenna controller is described. The chip provides a low-cost means for passing 400-Mb/s antenna control information using fiber optics with a very low bit-error rate (BER). Approximately 350 source-coupled FET logic gates are present on the chip. A new data coding and timing recovery scheme that is highly tolerant to jitter over a wide bandwidth has been developed. The OEIC uses an on-chip metal-semiconductor-metal (MSM) photodiode with 0.12-A/W responsivity measured at 780 nm and was fabricated in a 1.0-mm GaAs MESFET manufacturing technology. The low capacitance semi-insulating GaAs substrate minimizes the coupling between analog and digital circuitry. The circuit operates from a single 5-V supply, consumes 1 W of power, and provides an 8-b CMOS output bus together with various utility flags. Optical sensitivity is estimated at -20 dBm for 10^-14 BER     

10Gb/s突发模式时钟数据恢复电路设计

突发模式的时钟数据恢复是10G EPON系统的关键技术之一。本文介绍了一种基于XNOR/XOR门的振荡器,分析了其工作原理与性能,以此为基础设计了半速率突发时钟恢复电路。设计采用SMIC 0.13?m CMOS工艺进行了流片验证,芯片面积为675?m ? 625?m。测试结果表明,该电路可以即时的实现10Gbit/s的突发数据恢复,恢复出的时钟数据符合IEEE 802.3av标准,锁定时间小于5bit。     

A practical approach to evaluating test results

The author describes the procedure used at NCR Corporation to evaluate the data collected during usability tests. He points out that it can be overwhelming to face a mass of data to be compiled, categorized, analyzed, and evaluated at the end of a test, with limited time available for producing a report. This situation is avoided by defining, before a test, the tools that will be used to collect the test data and the process by which the results will be evaluated, and then performing the preliminary evaluation of data in a process parallel with the test itself. At the end of the test, an evaluation meeting is held at which the cumulative results are reviewed and solutions to the problems that have been identified are defined     

Optimum look weighting for burst-mode and ScanSAR processing

Burst-mode and ScanSAR systems record only short pieces of Doppler histories; the energy contained in each echo ensemble and, hence, the intensity in the final burst image (look) depends on the scatterer's position relative to the time of the burst event according to the azimuth antenna pattern, an effect known as scalloping. Most systems employ a burst period short enough that adjacent looks overlap allowing for individual weighting of the looks before summation. The paper introduces a new class of look weighting functions for burst-mode and ScanSAR processing that correct for scalloping while simultaneously keeping the S/N ratio constant over azimuth and maximizing the equivalent number of looks. The achievable radiometric resolution and the sensitivity to Doppler centroid estimation errors are discussed. A 3-look example using ASAR parameters illustrates the proposed weighting functions     

A 156-Mb/s CMOS optical receiver for burst-mode transmission

In a point-to-multipoint fiber-optic subscriber system using TDMA (time division multiple access), the receiver should be able to handle burst-data packets with different amplitudes, Moreover, high-bit-rate operation is desired for multimedia communications. The operational speed is mainly restricted by the input parasitic capacitance of the preamplifier. Reducing the input impedance of the preamplifier widens its frequency bandwidth, and it makes high-speed operation possible. A multistaged preamplifier using feedforward phase compensation technique has been devised for small input impedance with stable operation at high frequency. Multistaged feedforward bias control is used for quick response to burst data, and the time constant is also reduced for high-speed operation. Using these design techniques, an optical receiver IC was fabricated using standard 0.5-μm CMOS technology. The instantaneous response receiver has high sensitivity of -35.6 dBm, a wide dynamic range of more than 26 dB for burst-mode optical input at 156 Mb/s, and requires no external adjustment. The use of standard CMOS technology and the freedom from external adjustment make it possible to build an inexpensive receiver module     

Performance analysis of burst-mode receivers with clock phase alignment and forward error correction for GPON

We experimentally demonstrate the performance analysis of burst-mode receivers (BMRx) in a 622 Mb/s 20-km gigabit-capable passive optical network (GPON) uplink. Our receiver features automatic phase acquisition using a clock phase aligner (CPA), and forward-error correction using (255, 239) Reed-Solomon (RS) codes. The BMRx provides instantaneous (0 preamble bit) phase acquisition and a packet-loss ratio (PLR) < 10^?6 for any phase step (±2π rads) between consecutive packets, while also supporting more than 600 consecutive identical digits (CIDs). The receiver also accomplishes a 3-dB coding gain at a bit-error rate (BER) of 10^?10. The CPA makes use of a phase picking algorithm and an oversampling clock-and-data recovery circuit operated at 2× the bit rate. The receiver meets the GPON physical media dependent layer specifications defined in the ITU-T recommendation G.984.2 standard. We investigate the PLR performance of the system and quantify it as a function of the phase step between consecutive packets, received signal power, CID immunity, and BER, while also assessing the tradeoffs in preamble length, power penalty, and pattern correlator error resistance. We also study the impact of mode-partition noise in the GPON uplink in terms of the effective PLR and BER coding gain performance of the system. In addition, we demonstrate how the CPA and the RS(255, 239) codes can be used in tandem for dynamic burst-error correction giving reliable BERs in bursty channels.     

GPON突发模式误码测试系统的设计与实现

文章阐述了光模块突发接收误码测试的基本原理.根据吉比特无源光网络(GPON)系统上行数据的特点,提出了一种新的突发数据提取方法及其关键技术,并设计了实现突发测试的逻辑框图、逻辑时序图及电路.采用该测试系统对GPON光线路终端(OLT)光模块进行了测试,结果表明该系统操作简单,可靠性高,能够满足GPON OLT光模块性能...     

Theory of burst-mode receiver and its applications in opticalmultiaccess networks

In this paper, a unified theory for the newly developed optical burst-mode receiver is presented. Based on this theory, an analysis of the performance of the receiver is given both theoretically and experimentally. The theoretical model agrees well with the experimental results. This theory can quantitatively explain the bit error rate (BER) performance of burst-mode receivers. Several potential applications of burst-mode receivers are also illustrated, including applications in supervisory system for erbium-doped fiber amplifier (EDFA) trans-oceanic optical links and various high-speed all-optical multiaccess packet networks     

Designs for pilot-symbol-assisted burst-mode communications with fading and frequency uncertainty

High performance and reasonable complexity have made pilot-symbol-assisted modulation (PSAM) of great practical interest in mobile communications. However, no previous work has investigated PSAM in burst-mode operation which is commonly encountered in multiple-access schemes (time-division or slow-frequency-hopped system). This paper examines the burst structure design problem in a frequency-flat fading environment. The explicit relationship between error performance and the design parameters, including pilot allocation, frequency offset, Doppler spread, and modulation scheme, is explored. Periodic pilot insertion commonly used for continuous transmission produces degraded performance in burst-mode operation. A new, unequal-pilot-spacing burst architecture is proposed in this paper to achieve better error performance. This work also focuses on the potential performance improvement of a frequency offset estimator and a Doppler spread estimator. The results show that an improvement up to 2.5 dB in SNR/bit can be attained by a Doppler spread estimator. A significant frequency offset can produce an irreducible error floor or a severe reduction in the throughput rate if no compensation is implemented. The performance degradation investigated in this paper can be used to determine the specification of the frequency offset estimator and the Doppler spread estimator used in conjunction with PSAM.     

Uncertainty analysis of the CISPR/a radiated emission round-robin test results

A large round-robin test (RRT) was carried out to obtain quantitative information about the uncertainties that play a role in an International Electrotechnical Commission/International Special Committee on Radio Interference (IEC/CISPR) radiated emission test in the frequency range 30 to 300 MHz. Two different equipment under tests (EUTs) allowed us to distinguish between the measurement instrumentation and the EUT-induced uncertainties, a subset of the standards compliance uncertainties. This paper presents the rationale behind the various RRT-measurements, the way the ancillary equipment was continuously checked, the measurement results and the results of their statistical analysis. The test sites included open-area test-sites, semi-anechoic rooms and fully anechoic rooms. A major conclusion is that measurement instrumentation uncertainty considerations alone cannot explain the uncertainty relevant in an actual CISPR radiated emission compliance test.     

A large-signal analysis of the traveling-wave amplifier: Theory and general results

Equations are derived describing the large-signal operation of the traveling-wave amplifier, including the effects of ac space charge and attenuation along the helical slow-wave structure. The equations constitute a system of nonlinear partial-differential-integral equations valid with reasonable approximations for all values of the parameters which are encountered in typical high-power traveling-wave amplifiers. The parameters which appear in the equations are the relative injection velocity b, the gain parameter C, the large-signal space-charge parameters K and B, the loss parameter d, and the input-signal level A0. The working equations were programmed for and solved on the Michigan Digital Automatic Computer, MIDAC, located at the University of Michigan's Willow Run Research Center. The rf voltage amplitude A(y), the phase lag of the rf wave relative to the electron stream θ(y), and the velocity deviation 2Cu(y, φ0) were computed and plotted for several values of C, K, b, and B at A0= 0.0025, and d = 0. Also, distance-phase plots are presented for each of the above cases. These flight-line diagrams for the traveling-wave amplifier are similar to the well-known "Applegate diagram" associated with klystrons. Zero-space-charge solutions are presented for C = 0.05, 0.1, and 0.2 with b as the parameter in order to determine the value of b which gives the maximum saturation gain and the optimum tube length. For C = 0.1 similar solutions are obtained for several values of the space-charge parameter K. Presented in graphical form, the results of these various solutions shed a considerable amount of light on the high-level operation of the traveling-wave amplifier.     

一种适用于突发相干光通信的均衡和频偏估计的联合方法

为了适应光突发接收机的快速信道均衡和频偏估计的要求,提出一种时域均衡联合频偏估计的方法。频偏估计的叠加结果作为反馈用于电信道均衡器误差信号的计算,同时用于均衡器估计值的频偏补偿。通过仿真验证了时域均衡联合频偏估计可以提高系统性能,并对影响光突发接收机的参数设置进行了研究;仿真研究了自适应均衡联合频偏估计时光突发接收机适用的稳态频偏和光纤传输距离范围,当系统中存在1GHz的频偏时系统仍然能够传输180km以上。研究结果表明,本文提出的时域均衡联合频偏估计的算法,在当光突发接收机中存在频偏暂态效应时仍然能够有效完成信道均衡和频偏估计与补偿。     

A CMOS burst-mode optical transmitter for 1.25-Gb/s ethernet PON applications

This brief presents a CMOS burst-mode optical transmitter suitable for use in 1.25-Gb/s Ethernet passive optical network applications. Based on feedback from the monitoring photodiode, in order to control consecutive burst data the proposed transmitter in this brief uses a reset mechanism, which allows fast responses from the beginning of a high-speed input burst. The chip is fabricated in mixed-mode 0.18-/spl mu/m CMOS technology and measurements are implemented in a chip-on-board configuration using a pig-tailed type Fabry-Perot laser. Under burst-mode operation of 1.25-Gb/s pseudorandom binary sequences, measurements show about 1-dBm averaged transmitted optical power with an over 12-dB extinction ratio over a wide temperature range.     

A fixed-frequency modified series-resonant converter: analysis,design, and experimental results

It is shown that a fixed-frequency modified (LCL-type) series-resonant converter operates in five different modes with variations in the load current and the supply voltage. The converter is analyzed using the state-space approach for these operating modes. Both the general solutions and the steady-state solutions are obtained. Based on the analysis, design curves are obtained and a simple design procedure is illustrated using a design example. Detailed experimental results obtained from a MOSFET-based 500 W converter are presented to verify the analysis. It is shown that using a proper design, the converter operates only in modes 2 and 3, ensuring a lagging power factor mode of operation for very wide variations in the load and supply voltage     

Lead-free 0201 manufacturing, assembly and reliability test results

The trend towards smaller, faster and cheaper electronic devices has led to an increase in the use of 0201 (L  0.02 in.; W  0.01 in.) and even smaller sized passive components. The size advantages of the 0201 component make it a popular choice among design engineers but not among manufacturing engineers. From a manufacturing perspective, the size of the 0201 package poses significant challenges to the printed circuit board (PCB) assembly process. The many challenges with 0201 assembly can be attributed to the solder paste volume, pad design, aperture design, board finish, type of solder paste, pick-and-place and reflow profile. If these factors are not optimized, they will introduce undesirable manufacturing defects. The small size of 0201 packages and undetected manufacturing defects will also raise concerns about their second level interconnect reliability, especially for lead-free solder alloys and surface finishes, with new processes and higher reflow requirements. To determine the optimum conditions, a design-of-experiment (DOE) study was carried out to investigate the effects of these parameters on assembly defects and solder joint reliability.This paper presents the test results and comparative literature data on the influence of a few key manufacturing parameters and defects associated with the 0201 component using lead-free and tin–lead solder alloys. Data pertaining to component shear strength before and after isothermal aging at 150 °C and intermetallic growth up to 500 h of aging are presented. A number of test vehicles were also subjected to thermal cycling (1500 cycles) in the range of −55/100 °C to determine the solder fatigue behavior. Shear test results for test vehicles subjected to thermal cycling is also presented. In addition, optical microscopy analysis of solder joint behavior during thermal cycling showing the progress of the solder damage and cross-sectional photos taken at 1500 cycles is included.