采用DS-CDMA方式的超宽带技术研究与应用

对超宽带（UWB）技术的起源和在现阶段的发展概况进行了阐述，讨论了DS-CDMA实现方式的技术特点，通过对技术参数的分析，说明了DS-UWB技术的利弊所在，同时介绍了DS-UWB当前的应用情况和发展前景。     

光学磁场传感器中超宽带模拟信号的重构

为了解决光学脉冲磁场传感器中超宽带模拟光信号的数据采集与波形重构,本文提出了一种基于频带分割与频谱搬移的模拟信号重构方法。在频域上采用分割滤波器进行频带分割,在每个采样通道内对输入的子带信号进行采样,降低了对ADC采样速率的要求,再由各个通道的采样序列重构原模拟信号。该方法有效解决了光学磁场传感器中带宽高达几千兆赫的信号无法直接进行A/D转换的难题。给出了重构算法并进行了计算机仿真。仿真结果证实,滤波器的特性决定了重构的精度。所提出的方法具有较高的信号重构精度和较小的频谱失真。     

一种小型陷波多用途超宽带天线

提出了一种小型陷波多用途超宽带微带天线。该天线与一般的宽缝隙微带天线类似,通过在矩形调谐支节上开V形缝隙获得了陷波特性。通过数值仿真和实验测量,对天线的阻抗特性、方向图和增益进行了研究。结果显示该天线在2.4到11GHz频段内驻波比小于2,在5.15~5.95 GHz范围内具有陷波特性。同时该天线还可覆盖2.4GHz无线局域网(WLAN)频段,在整个工作频段内有良好的辐射方向特性。     

一种新型双陷波超宽带天线设计

设计了一种新型双陷波超宽带印刷天线。辐射贴片底部为梯形结构,实现了良好的阻抗匹配。通过在贴片上加载两个U型缝隙,分别在中心频率3.5GHz和5.5GHz处产生陷波。比较陷波前后天线表面电流密度,并用传输线理论对陷波产生机理进行了分析。天线实测与仿真结果吻合,通带内天线辐射效果良好,陷波频段内增益下降超过5dB,达到了陷波抑制的效果。     

A SiGe LC-ladder low noise amplifier with base resistance match,gain and noise flatness for UWB applications

This study presents a 3.1–10.6 GHz ultra-wideband low noise amplifier (UWB LNA) in 0.18 µm SiGe HBT technology. To achieve a good input match, parasitic base resistance in a bipolar transistor and an LC-ladder filter are included into calculations with the common-emitter topology using shunt–shunt capacitive feedback. Both high and flat power gain (S₂₁) and low and flat noise figure (NF) are achieved by adjusting the pole and zero in amplifying stage and quality factors of the fourth-order input network. Design equations for performances such as gain, noise figure and linearity IIP3 are derived especially on gain flatness and noise flatness. LNA dissipates 33 mW power and achieves S₂₁ of 20.65+0.7 dB, NF of 2.79+0.2 dB over the band of 3.1–10.6 GHz. The simulated input third-order intermodulation point (IIP3) is −17 dBm at 10 GHz.     

Low power high gain CMOS LNA based on inverter cell and self-body bias for UWB receivers

A low-power low-noise amplifier (LNA) utilized a resistive inverter configuration feedback amplifier to achieve the broadband input matching purposes. To achieve low power consumption and high gain, the proposed LNA utilizes a current-reused technique and a splitting-load inductive peaking technique of a resistive-feedback inverter for input matching. Two wideband LNAs are implemented by TSMC 0.18 μm CMOS technology. The first LNA operates at 2–6 GHz. The minimum noise figure is 3.6 dB. The amplifier provides a maximum gain (S₂₁) of 18.5 dB while drawing 10.3 mW from a 1.5-V supply. This chip area is 1.028×0.921 mm². The second LNA operates at 3.1–10.6 GHz. By using self-forward body bias, it can reduce supply voltage as well as save bias current. The minimum noise figure is 4.8 dB. The amplifier provides a maximum gain (S₂₁) of 17.8 dB while drawing 9.67 mW from a 1.2-V supply. This chip area is 1.274×0.771 mm².     

Ultra wideband NIR emission in all-inorganic lead-free metal halides through Sb3+ doping

In recent years, food detection, plant photosynthesis, night vision, and the identification of biological data have all benefited from near-infrared luminescence. However, developing metal halides emitting near-infrared (NIR) light is still difficult, which restricts further applicability. Here, we propose an insightful methodology to investigate the wideband NIR emission in metal halide Cs₂ZnCl₄ host by doping Sb³⁺. The phosphors are successfully synthesized by the coprecipitation method and the photoluminescent properties are explored in detail. Based on the spectroscopic information, experimental data with DFT calculations, and luminescence kinetics investigation of Sb³⁺ doped Cs₂ZnCl₄, the broadband red emission is caused by self-trapped excitons, which can be attributed to the ³P₁–¹S₀ transitions. The spectra under the excitation at 351 nm exhibit an ultra-wideband emission with a center wavelength of 737 nm, an FHWM of 196 nm, and a significant Stokes shift of 386 nm. The NIR LED fabricated by Cs₂ZnCl₄: Sb³⁺ can also be used in night vision devices and biological identification. Our findings in Sb³⁺ doped Cs₂ZnCl₄ materials provide light on how doping induces emission centers and expand our understanding of the optical characteristics of doped lead-free metal halides for future research. This work also offers recommendations for broadening the range of uses for luminous metal halides and proposes an efficient method for developing fresh environmentally friendly and wideband emission NIR phosphors.     

The ultra-wideband near-infrared luminescence properties and applications of K2SrGe8O18:Cr3+ phosphor

The near-infrared (NIR) light sources are fascinating in real-time nondestructive examination applications. Given that chemical bonds in organic substances (such as C–H, O–H and N–H) have extensive absorption and reflection of light in the NIR region, the emission spectrum of the NIR light sources should be as broad as possible. In this work, ultra-wideband K₂SrGe₈O₁₈ (KSGO):Cr³⁺ NIR-emitting phosphors with a 650–1200 nm emission span are developed. Structural analysis combined with electron paramagnetic resonance (EPR), photoluminescence (PL) spectra, time-resolved spectrum (TRES) and temperature-dependent PL spectra confirm that the super broadband emission with full width at half-maximum (FWHM) of 214 nm originates from the double Cr³⁺ luminescence centers occupying different [GeO₆] octahedra. Li⁺ ion as charge compensator is introduced to balance the negative charge induced by the un-equivalent replacement of Cr³⁺ for Ge⁴⁺, and the PL intensity and thermal stability are greatly enhanced. The NIR phosphor-converted luminescent diodes (pc-LEDs) prepared by combining optimized KSGO:0.10Cr³⁺, 0.07Li⁺ samples with 460 nm LED chips demonstrate their application in night vision. The measured absorption spectra of hemoglobin, water, ethyl alcohol and peanut oil illuminated by the as-prepared KSGO:0.10Cr³⁺, 0.07Li⁺ phosphors indicate nondestructive analysis in the areas of food safety.