一种新型的漂移阶跃恢复二极管脉冲源设计

提出了一种基于漂移阶跃恢复二极管（DSRD）、结构简单的新型大功率脉冲源电路.论述了阶跃恢复二极管的快速开关特性,分析了该新型脉冲源电路的工作原理,并进行了实验测试.实验结果表明,脉冲源电路能够产生峰峰值为760 V、脉宽（10％-10％）8 ns的平衡输出脉冲信号,具有脉冲重频高、振铃小、波形质量高、无需高压供电等特点,适用于深层探测超宽带时域脉冲探地雷达系统.     

一种新型的超宽带锥削缝隙天线设计

提出了一种微带线-槽线馈电形式的指数锥削缝隙天线,在辐射臂的外边缘引入半椭圆形缝隙来进一步提高天线低频段的定向性,获得了高增益和超宽带性能。利用HFSS12软件进行仿真,天线的极化方式为垂直极化,在2~13 GHz的工作频段内电压驻波比＜2,增益最高达11 dB,具备良好的定向性,仿真与实测结果基本吻合,表明该设计是有效、可行的。     

A new ultra-wideband fractal monopole antenna

The paper focuses on the peculiar dynamic behaviour of the recently developed 8 mm² TO-220-packaged, high-voltage, double-interdigitated (or rwo interdigi-tation levels—TIL) GTO thyristor. This novel power device was rated under both slightly and heavily inductive resistive loads, i.e. close to the real conditions encountered in practical power circuits employing GTO thyristors. Emphasis is laid on the ability of TIL GTOs to switch safely, with minimum power losses, a certain amount of anode current under high-voltage conditions and high commutation frequencies. The merits of TIL GTO thyristors are analysed in terms of their reliability and switching efficiency, which include the total power losses (conduction and switching losses), turn-on and turn-off gains and the switching speed. It is shown that thanks to their built-in self-protective features, these novel GTOs possess an enhanced current-handling capability at commutation frequencies up to 50kHz under extremely tough load conditions. The main implications of the results for power applications are outlined.     

A low-voltage ultra-wideband down-conversion mixer with improved power conversion gain

This article presents a wideband mixer using a TSMC 0.18?µm complementary metal-oxide semiconductor technology process for ultra-wideband (UWB) system applications. The measured 3-dB radio frequency (RF) bandwidth is from 3 to 8.4?GHz with an intermediate frequency of 10?MHz. The measurement results of the proposed mixer achieve 8.1?dB average power conversion gain ?5?dBm input third-order intercept point (IIP3) at 7.4?GHz and 12.4–13.3?dB double side band noise figure. The total dc power consumption of this mixer including output buffers is 3.18?mW from a 1?V supply voltage. The output current buffer consumption is about 2.26?mW with an excellent local oscillator-RF isolation of up to 40?dB at 5?GHz. The article presents a mixer topology that is greatly suitable for low-power operation in UWB system applications.     

A 0.7 V 6.66–9.36 GHz wide tuning range CMOS LC VCO with small chip size

The circuit designs are based on TSMC 0.18 μm CMOS standard technology model. The designed circuit uses transformer coupling technology in order to decrease chip area and increase the Q value. The switched-capacitor topology array enables the voltage-controlled oscillator (VCO) to be tuned between 6.66 and 9.36 GHz with 4.9 mW power consumption at supply voltage of 0.7 V, and the tuning range of the circuit can reach 33.7%. The measured phase noise is ?110.5 dBc/Hz at 1 MHz offset from the carrier frequency of 7.113 GHz. The output power level is about ?1.22 dBm. The figure-of-merit and figure-of-merit-with-tuning range of the VCO are about ?180.7 and ?191.25 dBc/Hz, respectively. The chip area is 0.429 mm² excluding the pads. The presented ultra-wideband VCO leads to a better performance in terms of power consumption, tuning range, chip size and output power level for low supply voltage.     

具有双陷波特性的超宽带天线设计

设计了一款基于共面波导馈电的小型化具有双陷波特性的超宽带天线,该天线的带宽在3～14 GHz内,电压驻波比(VSWR)小于2。在辐射贴片上通过开L型和半圆环缝隙实现了在3.3～3.7 GHz和5.150～5.825 GHz的双频段的陷波特性,抑制了802.16无线城域网和无线局域网对超宽带系统的干扰,在整个工作频段具有稳定的增益和良好的全向性。通过对天线模型进行加工制作并测量,测试结果表明:天线的带宽是3～14 GHz,在3.3～3.7 GHz和5.15～5.825 GHz频段内VSWR大于4,实现了天线的双陷波特性。该天线尺寸小、结构紧凑的特点,适合现代的无线通信系统。     

等阻抗超宽带高能微波发生器模拟研究

基于等阻抗-双脉冲成形线技术,建立了一个超宽带高能高功率微波发生器理论模型。计算机模拟结果表明:利用等阻抗超宽带高功率微波发生器,可以同时产生纳秒主脉冲和皮秒前沿脉冲;通过控制皮秒脉冲成形线输出开关闭合的延迟时间,可以调制皮秒脉冲和纳秒脉冲的输出电压比值;通过调节纳秒脉冲成形线与皮秒脉冲成形线的电容比值,可以控制皮秒脉冲的脉宽和皮秒脉冲的峰值电压;利用等阻抗超宽带高功率微波发生器,可以最大限度地提高辐射脉冲能量和整个系统的能量转换效率。     

加脊TEM喇叭初步研究

针对恒阻抗TEM喇叭的上下面板电流分布不对称,采用小反射理论和阻抗渐变思想并通过设计脊结构对恒阻抗TEM喇叭进行了改进,研制了加脊TEM喇叭。仿真及实验研究结果表明:对于脉冲宽度约为1 ns的高斯脉冲,通过加脊在一定程度上改善了恒阻抗TEM喇叭上下面板电流分布的不对称性和E面辐射电场的不对称性;相对于相同口径的恒阻抗TEM喇叭,加脊TEM喇叭作为辐射天线和反射面脉冲天线馈源时系统的主轴远场辐射因子均有提高。     

A RF receiver frontend for SC-UWB in a 0.18-μm CMOS process

正A radio frequency(RF) receiver frontend for single-carrier ultra-wideband(SC-UWB) is presented. The front end employs direct-conversion architecture,and consists of a differential low noise amplifier(LNA),a quadrature mixer,and two intermediate frequency(IF) amplifiers.The proposed LNA employs source inductively degenerated topology.First,the expression of input impedance matching bandwidth in terms of gate-source capacitance, resonant frequency and target S_(11) is given.Then,a noise figure optimization strategy under gain and power constraints is proposed,with consideration of the integrated gate inductor,the bond-wire inductance,and its variation.The LNA utilizes two stages with different resonant frequencies to acquire flat gain over the 7.1-8.1 GHz frequency band,and has two gain modes to obtain a higher receiver dynamic range.The mixer uses a double balanced Gilbert structure.The front end is fabricated in a TSMC 0.18-/im RF CMOS process and occupies an area of 1.43 mm~2.In high and low gain modes,the measured maximum conversion gain are 42 dB and 22 dB,input 1 dB compression points are -40 dBm and -20 dBm,and S_(11) is better than -18 dB and -14.5 dB.The 3 dB IF bandwidth is more than 500 MHz.The double sideband noise figure is 4.7 dB in high gain mode.The total power consumption is 65 mW from a 1.8 V supply.     

基于分形理论的CUWB频谱感知方法

针对超宽带频带内授权信号类型确定的特点,为了弥补盒维数检测不能够有效识别信号类型的缺点,提出通过进一步提取信息维数特征对信号调制样式进行识别,该方法融合了盒维数检测和信息维数检测的优点进行合作判决。仿真表明基于信号分形理论的频谱感知能够取得较好的检测效果,且该方法运算复杂度低,对噪声不敏感,能够有效区别噪声与授权信号,抵御模拟授权用户攻击,检测效果优于循环谱检测和能量检测。