具有非线性电压转换有源箝位正激变换器

本文研究一种具有非线性电压转换的正激变换器,通过在有源箝位正激变换器的变压器二次侧增加一个续流二极管和一个输出滤波电感得到。该变换器保留了有源箝位正激变换器的优点,同时,具有更高的占空比利用率,使得其具有宽输入电压适应范围,软开关的实现和二极管电压电流应力的减小,使其功率转换效率进一步提高。研制了一台50~100V输入, 12V输出的原理样机,实验结果验证了理论分析的正确性以及该技术的可行性。     

NRZ-OOK-to-RZ-BPSK modulation-format conversion using SOA-MZI wavelength converter

A novel all-optical modulation-format conversion from nonreturn-to-zero on-off keying (NRZ-OOK) to return-to-zero binary phase-shift keying (RZ-BPSK) is proposed. A Mach-Zehnder interferometric (MZI) wavelength converter consisting of integrated semiconductor optical amplifiers (SOAs) is utilized to implement the proposed format conversion. Error-free operation at a bit rate of 10.7 Gb/s is experimentally demonstrated in order to show the feasibility of the proposed scheme. The received sensitivity of the converted signal is improved by 2.9 dB compared with a back-to-back NRZ-OOK signal at BER=10/sup -9/. In addition, a reasonable dispersion tolerance of the converted signal up to /spl plusmn/500 ps/nm is observed. The numerical simulation based upon the carrier-rate equation verifies the experimental results.     

An adaptive direct conversion transmitter

An adaptive direct conversion transmitter is presented, in which adjacent channel power measurements are used to simultaneously compensate for both power amplifier (PA) nonlinearity and quadrature modulator (QM) errors. Three main contributions are given. First, analysis is presented which shows that adjacent channel power is a quadratic function of power amplifier nonlinearity as well as quadrature modulator errors. Quadrature modulator errors are gain imbalance, phase splitter error, and DC offset errors. Second, a new optimization method is given which uses the predicted adjacent channel power surface to obtain fast convergence. Third, simulation and measured results are given for an adaptive system using offset QPSK modulation. The measured results confirm the analysis and show that a 20-dB reduction in adjacent channel power is achievable. In general, the adaptive direct conversion transmitter has applications in any system where power efficiency and spectral efficiency are important, and allows the use of smaller more efficient power amplifiers in a direct conversion architecture     

Active-clamp ZVS converter with step-up voltage conversion ratio

This article presents the circuit implementation and design considerations of a zero voltage switching (ZVS) converter with voltage step-up for battery-based applications. An active-clamp circuit including one auxiliary switch and one clamp capacitor is connected in parallel with the main switch to allow resonant behaviour by the output capacitances of switches and transformer leakage inductance during the transition interval. Thus, the ZVS turn-on of switches can be achieved. The switching losses and thermal stresses of the semiconductors are reduced. The circuit configuration, operation principle and design considerations of the converter are discussed in detail. Finally, experiments conducted on a laboratory prototype rated at 200 W are provided to verify the theoretical analysis and the effectiveness of the proposed converter.     

Time-interleaved pulse-shrinking time-to-digital converter with reduced conversion time

A silicon-efficient time-interleaved pulse-shrinking time-to-digital converter (TDC) is proposed. The proposed TDC consists of a 16-stage coarse pulse-shrinking TDC with constant per-stage shrinkage 4.8 ns and a pair of 16-stage fine pulse-shrinking TDCs operated in a time-interleaved manner with constant per-stage shrinkage 296 ps. A simple residual time extraction method is proposed to extract the residual pulse of the coarse TDC simultaneously with digitization carried out by the TDC so that the digitization can be carried out by both the coarse and fine TDCs simultaneously to minimize conversion time. The characteristics of the proposed TDC including silicon consumption, power consumption, conversion time, jitter, and mismatch-induced timing errors are investigated. The proposed TDC was implemented in an IBM 130 nm 1.2 V CMOS technology. Simulation results show that the TDC offers 0.296–76.8 ns dynamic range, 850 ps conversion time, 0.285 LSB differential nonlinearity, and 0.78 LSB integral nonlinearity while consuming 7 mW.     

Ultra-high-speed OTDM networks using semiconductor amplifier-basedprocessing nodes

The use of semiconductor amplifiers in high speed communications systems is reviewed. Processing of signals at 10 Gb/s in a 40-Gb/s OTDM network is demonstrated using nonlinear loop mirror configurations, and mode locked ring lasers. Particular attention is paid to the role of carrier density modulation, long believed to be a detrimental effect, and its useful exploitation     

RZ-DPSK OTDM demultiplexing using fibre optical parametric amplifier with clock-modulated pump

Optical demultiplexing for a 40 Gbit/s RZ-DPSK OTDM signal using a fibre optical parametric amplifier with a sinusoidal-clock-modulated pump is experimentally demonstrated. Less than 1.3 dB power penalty and around 30 dB gain are obtained for all four demultiplexed channels. Superior performance is obtained for the demultiplexed tributaries in RZ-DPSK OTDM systems compared with those in RZOOK OTDM.     

OTDM网与WDM网接口间的码型转换技术研究

利用半导体光放大器(SOA)和光带通滤波器(OBPF)构成了一个全光码型转换器.理论分析了码型转换的原理,得出了码型转换取决于光带通滤波器的3dB带宽以及探测光中心波长相对于光带通滤波器中心波长失谐量的结论,实验测得3dB带宽为0.17nm,失谐量△λ=0.62nm.最后通过仿真实现了10Gb/s数据信号全光归零(RZ...     

A negative impedance converter using an in-line cryotron

A negative impedance converter using a single in-line cryotron is presented. The design requires fewer active elements than conventional circuits.     

利用半导体光放大器环路镜实现4×2.5GHzOTDM解复用

报道了利用半导体光放大器环路镜对４×２．５ＧＨｚ光时分复用（ＯＴＤＭ）进行全光解复用的实验，实验结果表明用该方法解复用可得到具有很好消光比的解复用信号。     

Tapped-inductor buck converter for high-step-down DC-DC conversion

The narrow duty cycle in the buck converter limits its application for high-step-down dc-dc conversion. With a simple structure, the tapped-inductor buck converter shows promise for extending the duty cycle. However, the leakage inductance causes a huge turn-off voltage spike across the top switch. Also, the gate drive for the top switch is not simple due to its floating source connection. This paper solves all these problems by modifying the tapped-inductor structure. A simple lossless clamp circuit can effectively clamp the switch turn-off voltage spike and totally recover the leakage energy. Experimental results for 12V-to-1.5V and 48V-to-6V dc-dc conversions show significant improvements in efficiency.     

Full-CMOS 2-GHz WCDMA direct conversion transmitter and receiver

This paper presents a full-CMOS transmitter and receiver for 2.0-GHz wide-band code division multiple access with direct conversion mixers and a DC-offset cancellation scheme. The direct conversion scheme combined with a multiphase sampling fractional-N prescaler alleviates the problems of the direct conversion transmitter and receiver. Digital gain control is merged into the baseband filters and variable-gain amplifiers to optimize the linearity of the system, reduce the noise, and improve the sensitivity. Variable-gain amplifiers with DC-offset cancellation loop eliminate the DC-offset in each stage. The chip implemented in 0.35-/spl mu/m CMOS technology shows the experimental results of 6 dBm maximum output power with 38-dB adjacent channel power rejection ratio at 1.92 MHz, 50-dB dynamic range, and 363-mW power consumption in the transmitter. The receiver shows -115.4 dBm sensitivity, a 4.0-dB noise figure, and a dynamic range of 80-dB with 396-mW power consumption.     

Simultaneous high speed OTDM add-drop multiplexing using GT-UNI switch

The authors describe the excellent capability of an all-optical gain-transparent ultrafast nonlinear interferometer (GT-UNI) in dropping, passing through, and adding optical time domain multiplexing (OTDM) channels. Error free operation without significant penalties of a complete OTDM add-drop node at 80 Gbit/s was achieved.     

3.8-THz wavelength conversion of picosecond pulses using asemiconductor delayed-interference signal-wavelength converter (DISC)

A new all-optical semiconductor-band-filling-based wavelength converter, named delayed-interference signal-wavelength converter (DISC), is proposed. Its speed is not restricted by the carrier lifetime and its structure is very simple: it consists of only two essential components, namely, a semiconductor optical amplifier and a passive split-delay. Using this converter, 3.8-THz-shifted (from 1530 to 1560-nm) 14-ps-long pulses are generated from 1530-nm 140-fJ 0.7-ps pulses with high-conversion efficiency     

无线发射机镜像抑制的Hilbert变换方法分析

采用超外差结构的无线发射机都会产生镜像频谱分量,如果不采取抑制措施,必然对其他信道产生严重的干扰,同时带来发射机效率降低、浪费频谱资源等问题。镜像抑制一直是无线发射机设计中的重点问题。从无插值镜像及有插值镜像2个方面,分析了实现镜像频谱抑制的Hilbert变换方法,对无线发射机镜像频谱抑制的设计与实现具有重要的借鉴意义。     

Wide-range all-optical wavelength conversion usingdual-wavelength-pumped fiber Raman converter

A wavelength conversion scheme based on a fiber Raman converter is proposed, in which an externally injected high power pump laser and the associated Stokes laser are used to assist the Raman conversion process of signal light coded with optical information. Because the Raman gain spectrum in fibers is extremely broad, a wavelength conversion device with wide-range tunability is feasible. We numerically demonstrate that wavelength conversion from 1.31 to 1.42 μm can be realized using a fiber Raman converter at up to 10 Gb/s with an efficiency of 18%. It is also demonstrated that wide range conversion from 1.31 to 1.55 μm for optical fiber communication is feasible at up to 5 Gb/s when the fiber Raman converters are cascaded twice     

一款高效率频率选择表面圆-线极化转换器

为了实现圆极化波到线极化波的高效率转换,提出了一种由两种圆极化波调制模块构成的复合结构单元频率选择表面圆-线极化转换器。采用天线-馈线-天线结构设计了左-左旋和左-右旋两种圆极化调制模,并将二者组合形成具有左旋圆极化波接收、左旋和右旋圆极化波同幅同相辐射功能的圆-线极化转换器。仿真与测试结果表明,该极化转换器能够将入射左旋极化波转换成线极化波,3 dB传输系数相对带宽大于19.8%,工作带宽内的圆-线极化转换率大于0.99。该极化转换器具有插入损耗低、设计原理易于推广等优势。     

采用SOA的以太网媒体转换器的设计与实现

双绞线/光纤媒体转换器可以大大扩大LAN的直径，解决LAN设备之间不同接口互相匹配问题，实现以太网信号在不同传输介质之间的转换，文章介绍了一种10Base-T双绞线/光纤媒体转换器的工作原理，设计与实现，由于光源选用SOA，故此媒体转换器的波长符合DWDM系统需求并且波长可调，最后还给出了实验结果和结论。