直扩信号检测的相关积累技术

分析直接序列扩谱信号与噪声在统计特征上的差别,在此基础上,提出利 用相关积累的思路来检测直扩信号载频和码速的方法。这种相关积累技术充分 利用了伪噪声和噪声之间的统计差别,以较长的积累时间,来获得低信噪比下检 测扩谱信号的能力。在仿真验证中,对于 ＧＰＳ的 Ｐ码信号,在信噪比为－２６ ｄＢ(带内信噪比为－１２ ｄＢ）时,相关积累 ０．５～１ｓ钟后,扩谱信号的载频和码速被准 确估计出来,其误差在１１ ｋＨｚ以内。     

低噪声掺Pr^3＋氟化物光纤放大器

研制了用Ｎｄ－ＹＬＦ激光器泵浦的掺Ｐｒ＾３＋氟化物光纤放大器（ＰＤＦＡ）组件，其最大信号增益和噪声指数分别是２０ｄＢ和５ｄＢ。在输入信号功率１１．０ｄＢｍ时，得到１９．２ｄＢｍ的输出功率，试验结果证明：该ＰＤＦＡ组件用于副载波复用多信道ＡＭ－ＶＳＢ视频信号传输时，具有低噪声特性。     

6～18GHz宽带功率放大器模块

研究了ＧａＡｓ功率ＭＥＳＦＥＴ的小信号特性、大信号特性和其宽带匹配网络。选用ＴＷＴ－２型功率器件，设计研制出了单级宽带功率放大器。在６～１８ＧＨｚ的工作频率范围内，小信号增益等于５．０±１．０ｄＢ，１ｄＢ压缩输出功率等于２５．０±０．８ｄＢｍ，输入输出驻波比小于２．５。     

固态大功率宽带射频放大器

Ｏｐｈｉｒ推出了５０８０、５３０３０Ｂ和４０７６系列固态大功率宽带射频放大器,其工作频率分别为０．８～４．２ＧＨｚ、４．０～８．０ＧＨｚ、５．９～６．４ＧＨｚ,相应的输出功率分别为１００Ｗ、０６Ｗ和１２０Ｗ。该系列放大器具有极好的线性度和较宽的动态范围,失真小,噪声低,体积小,重量轻。５０８０型１ｄＢ压缩点的输出功率为８０Ｗ,三阶截断点为+６０ｄＢｍ,小信号增益为４８ｄＢ,增益平坦度为±２００ｄＢ,输入／输出驻波比小于２,交流输入功率为４５０Ｗ;５３０３０Ｂ型１ｄＢ压缩点的输出功率为０５Ｗ,三阶截断点为+３７…     

6～18GHz宽带功率放大器模块

研究了ＧａＡｓ功率ＭＥＳＦＥＴ的小信号特性，大信号特性和其宽带匹配网络。选用ＴＷＴ－２型功率器件，设计研制出了单级宽带功率放大器，在６～１８ＧＨｚ的工作频率范围内，小信号增益等于５．０±１．０ｄＢ，１ｄＢ压缩输出功率等于２５．０±０．８ｄＢｍ，输入输出驻波比小于２．５。     

微波副载波复用视频光纤传输系统

介绍一个采用国产光电器件研制的微波副载波复用光纤视频传输系统。系统进行了以传输亚洲一号卫星信号地面接收站第一中频多路电视信号为目标的现场实验。信号经过３８．７８ｋｍ，１．３μｍ波长单模光纤传输后，在接收光功率为－２２ｄＢｍ时，载噪比劣化不大于３ｄＢ，当接收光功率为－３０ｄＢｍ时。     

高增益硅超高频功率SIT

采用全自对准介质盖栅工艺，通过合理设计，研制成功一种高增益硅超高频功率ＳＩＴ。在４００ＭＨｚ工作频率，５０Ｖ工作电压下，其输出功率Ｐ０为４０Ｗ，漏极效率η０接近６０％，功率增益Ｇｐ，高达１６ｄＢ，Ｐ０＝２５Ｗ时，三阶交调３ＩＭ为－１６ｄＢ，Ｐ０＝２．５Ｗ时，３ＩＭ为－５０ｄＢ。     

低反射率光纤镜的制造

低反射率光纤镜是采用机械连接的方式在光纤的粘结端用一层ＴｉＯ２介质膜涂覆而成。当光纤镜的反射率为０．１％时，插入损耗为０．０５５ｄＢ－０．３ｄＢ，平均０．１５ｄＢ。     

非线性调频信号时域旁瓣抑制滤波器设计

本文研究较小时带积的非线性调频信号以 Ｎｙｑｕｉｓｔ速率采样在时域进行压缩处理的数字 ＦＩＲ滤波器设计问题。重新定义目标函数和约束条件,利用迭代加权最小二乘技术,得出了又一种设计算法。模拟和实验表明,设计处理结果在多普勒频移 ｆ_ｄ＝０时,控制 ４ｄＢ主瓣展宽并使失配信噪比损失有限条件下,峰值旁瓣电平抑制较匹配处理提高了６～１０ｄＢ。     

光纤有线电视系统中掺铒光纤放大器的研制

成功地解决了ＣＡＴＶ光纤放大器的技术难点：（１）增益,噪声与泵浦功率的关系;（２）增益,噪声与掺铒光纤长度的关系;（３）增益,噪声与泵浦方式的关系。研制成功的ＣＡＴＶ光纤放大器具有输出功率大、增益高、噪声低和频带宽等特点,在输入光功率０￣＋６ｄＢｍ时,输出光功率１８ｄＢｍ,典型噪声系数４．６ｄＢ,小信号增益为３２ｄＢ,工作波长范围为１５４０￣１５６５ｎｍ。     

ADPCM with a multiquantizer for speech coding

A speech coding algorithm with low complexity and a short processing delay is introduced. The proposed algorithm is ADPCM (adaptive digital pulse code modulation) with a multiquantizer (ADPCM-MQ). The input signal is processed in parallel by multiple ADPCM coders with different characteristics. Then the optimum ADPCM coder with minimum error power is dynamically selected for each frame. A 16-kb/s codec based on this algorithm has been implemented using two general-purpose digital signal processors (MB8764) with 8.3 ms of total processing delay. A segmental SNR of 19-21 dB was achieved at 16 kb/s; with postfiltering the segmental SNR was increased to 23-25 dB. Combined with the time domain compression scheme, the algorithm can be easily applied to 8-kb/s coding. It is also extensible to variable-rate coding     

Optimization of pump and signal powers for wavelength converters based on FWM in semiconductor optical amplifiers

We investigate the effect of input pump and signal powers on the noise performance and intersymbol interference (ISI) in a frequency-converter based on four-wave mixing (FWM) in a semiconductor optical amplifier. We demonstrate that there is an input pump power at which the noise figure of the frequency converter is a minimum, and a corresponding input signal power for which the output signal-to-noise ratio (SNR) is a maximum. We report bit-error-rate measurements which show that there is a trade-off between maximizing the output SNR, and minimizing intersymbol interference in the SOA. Consequently, the power penalty incurred in the frequency conversion can be minimized by careful selection of the input signal power. We show that power penalties of less than 1 dB are achievable.     

基于SOA交叉增益调制的2.5Gbit/s NRZ码 全光波长转换实验研究

基于SOA交叉增益调制效应(XGM)进行了2.5Gbit/s 31位非归零(NRZ)伪随机码的全光波长转换实验,分析了该方案下转换信号的消光比、信噪比、平均功率与输入连续光、信号光功率、波长的关系.实验中转换信号的光信噪比可达40dB以上,消光比和信噪比均大于10dB,符合ITU-T G.691标准.信号波长向下转换间距可达60nm,是目前基于SOA中的XGM效应进行波长转换获得的最大的波长间距.     

A 10.7-MHz 68-dB SNR CMOS continuous-time filter with on-chipautomatic tuning

A maximally flat 10.7-MHz fourth-order bandpass filter with an on-chip automatic tuning system is presented. The signal-to-in-band integrated noise ratio (SNR) of the automatically tuned filter is around 68 dB. The third intermodulation distortion (IM3) is lower than -40 dB for a two-tone input signal of 3.2 V peak to peak (V_p-p). The complete system operates with supply voltages of ±2.5 V. The power consumption of the system is 220 mW. All this has been achieved due to the use of a low-distortion transconductor, the development of a high-frequency CMOS resistor, and the realization of an advanced on-chip automatic tuning system for both frequency and bandwidth control. The chip has been fabricated in a standard 1.5-μm n-well CMOS process     

A V-band up-converting InP HEMT active mixer with low LO-power requirements

In this letter, we present a monolithically integrated up-converting active mixer that shifts a signal in the 16 GHz range up to the V-band using a 48 GHz local oscillator (LO) signal. The circuit was realized with the 0.2 /spl mu/m InP HEMT in-house process of the Swiss Federal Institute of Technology in Zurich using coplanar-waveguide technology. Measurements of the fabricated circuit show a peak conversion gain of 1 dB at 64.5 GHz for -1.7 dBm LO power, LO suppression better than 30 dB and input third-order intercept point of -1.6 dBm. This mixer will be employed in the signal up-conversion path of a 60 GHz transceiver for indoor wireless LANs.     

相关检测在宽带雷达信号处理中的应用

通过对宽带雷达信号目标回波的分析，总结了其目标回波的主要特性。在比较几种经典信号检测方法的基础上，重点讨论了CDBPI和IPCD的方法，并对其性能和主要优缺点进行了分析。通过理论分析表明：在输入信噪比较大时，CDBPI方法可以精确地判定目标位置，而IPCD方法能够进一步提高输入信噪比。对IPCD方法的进一步研究表明：在低输入信噪比条件下，该方法具有更好的检测性能。用理想数据和实际数据进行仿真的结果表明，当采用32个脉冲重复周期进行积累后，IPCD方法比经典的能量积累的方法有1～2dB的信噪比提高。     

Transmitter leakage cancellation technique for CMOS SAW-less radio front-ends

Digital audio sensors have been used in microphone-embedded portable electronics. This paper shows a mixed-signal adaptive readout ASIC for digital audio sensor, which includes a programmable-gain-amplifier, a switched-capacitor sigma-delta modulator, digital signal processing, and power management circuits. The digital part comprises a digital low-pass filter, a digital-gain-compensation and a digital automatic-gain-controller. The clear advantage of this system is to obtain high signal-to-noise ratio (SNR) and wide input range simultaneously. In addition, both a normal operation mode and a sleep mode are realized to address a flexible current budget. The ASIC is fabricated in a 0.18-um CMOS process. Experimental results show the expected adaptive readout function over the input range from 94 to 136 dB SPL. In the normal mode, a system SNR of 68 dB (A-weighted) at 1 kHz 94 dB SPL input is achieved under 600 uA. Further, an impressive acoustic overload point (AOP) of 136 dB SPL is guaranteed. In the standby condition, the sleep mode with current less than 20 uA is obtained, so that the battery life can be extended. Compared to other existing solutions, this adaptive readout ASIC shows the best combination of achievable SNR, AOP and current budget for digital audio sensors.     

基于0.35 μm GeSi-BiCMOS工艺的1 GSPS采样保持电路

介绍了一种基于0.35μmGeSi-BiCMOS工艺的1GSPS采样/保持电路。该电路采用全差分开环结构,使用局部反馈提高开环缓冲放大器的线性度;采用增益、失调数字校正电路补偿高频输入信号衰减和工艺匹配误差造成的失调。在1GS/s采样率、484.375MHz输入信号频率、3.3V电源电压下进行仿真。结果显示,电路的SFDR达到75.6dB,THD为-74.9dB,功耗87mW。将该采样/保持电路用于一个8位1GSPSA/D转换器。流片测试结果表明,在1GSPS采样率,240.123MHz和5.123MHz输入信号下,8位A/D转换器的SNR为41.39dB和43.19dB。     

High-speed continuous-time band pass ΔΣ modulator for class-S systems

A fully integrated continuous-time bandpass delta-sigma modulator (BPDSM) fabricated in a 0.25 μm SiGe BiCMOS is presented. It consists of a two-stage second-order resonator, high-speed comparator, multi-feedback current digital-to-analog converter, and an output buffer. The input frequency can be tuned from 3.55 to 3.9 GHz at a 9.5 GHz fixed sampling clock frequency. This modulator dissipates 109 mA from a 3.3 V power supply. The peak signal-to-noise ratio (SNR) of the sine-wave input is 37.3 dB in a 20 MHz channel bandwidth, and the error vector magnitude (EVM) of a 64QAM long-term evolution (LTE) downlink signal is 5.94% with a 10.5 dB peak-to-average-power ratio (PAPR).     

Carrier detection of PSK signals

This paper reports on a theoretical study of the detection of the 2f and 4f carrier components of phase-shift keying (PSK) signals produced by passing signal and noise through a nonlinear device. Unbalanced quadrature PSK (QPSK) signals, i.e., QPSK signals with unequal power in the two channels, are studied. The complete range of channel power ratio is covered, with equal emphasis on the general unbalanced case and the two limiting cases of binary PSK and (balanced) QPSK. Analytic expressions are derived for the detected SNR of carrier harmonics 2f and 4f as a function of SNR, channel power ratio, and normalized input bandwidth. The results apply equally well to PSK data signals and direct-sequence spread-spectrum signals. Measurements confirm every aspect of the theory. The least detectable signal type is balanced QPSK, which is detectable (at 4f) at a threshold SNR ranging from -2 to -13 dB as the detection process gain (chip or data rate/detection bandwidth) is varied from 40 to 80 dB