Field trial of an HTS filter system on a CDMA base station

This paper presents the field trial results of a high temperature superconductor filter system (HTSFS) in a code division multiple access (CDMA) mobile communication base station (BTS) in Tangshan, China. The center frequency of the HTSFS is 830 MHz with 1.4% fractional bandwidth. The noise figure (NF) of the HTSFS, including connectors and cables, is 0.8 dB. The field trial results show that after the HTSFS was installed in the receiver front-end of a CDMA base station, the transmitting power of handset was decreased by 3.1 dB on average. Up to now, the HTSFS has been running steadily in the base station for more than 22 months, demonstrating the reliability and stability of the system.     

An L-band HTS duplexer with improved performance

An L-band HTS duplexer with improved performance for communication applications has been developed. This is an improved version of the duplexer previously developed by our group. The duplexer was composed of a T-junction and two channels. Each channel has a 10-pole quasi-elliptic function bandpass HTS filter with a bandwidth of 27 MHz, and center frequencies at 1200 MHz and 1260 MHz. To achieve higher performance, especially a good balance between selectivity and flat group delay, the two pairs of transmission zeros from the two filters were reassigned so that one pair is used for high selectivity and the other for flat group delay. To reduce the influence of parasitical coupling, new coupling structures were developed in the simulation process. The duplexer was fabricated on a 2 inch diameter, 0.5 mm thick LaAlO3 wafer with a double-sided YBCO film. The measured results showed a very high performance: a mid-band insertion loss of 0.2 dB, a return loss better than –14 dB, a shape factor better than 1.4:1, an out-of-band rejection of better than 70 dB in a wide frequency range up to 3 GHz and excellent isolation (higher than 80 dB) between the two channels. In addition, the frequency band 5 ns group delay variation is over 10.5 MHz (38.7% of 1 dB bandwidth).     

A high-performance narrowband high temperature superconducting filter

Recent development of a high-performance narrowband high-temperature superconducting (HTS) filter is presented. A 10-pole quasi-elliptic function response filter with two pairs of transmission zeros (for high selectivity), which has a center frequency of 2.185 GHz and a 3 dB bandwidth of 10 MHz (a fractional bandwidth of 0.45%), is introduced. The filter was fabricated on a 40 mm×16 mm×0.5 mm MgO wafer with double-sided YBCO films. The measured results show that the filter has 0.15 dB insertion loss at the ...     

Development of X-band high temperature superconducting filters

A synthesized design method is proposed to design microstrip band-pass filters. The impact of the box structure to the filter performance is considered besides the structure of microstrip. An X-band high temperature superconducting (HTS) microstrip filter for deep space network is designed using this method. The six-pole microstrip band-pass filter at frequency of 9500 ± 500 MHz is realized using TBCCO HTS thin film grown on 0.5 mm thick LaAlO3 substrate. The filter shows very high rejection of 90 dB in the...     

Design of high temperature superconducting contiguous-band diplexer

A high temperature superconducting (HTS) contiguous-band diplexer was designed and fabricated. The HTS contiguous-band diplexer was made using 2-inch-diameter LaA1O₃ wafers coated with epitaxial thin film YBO on both sides, and was made up of two 4-pole singly-terminated low-pass prototype bandpass channel filters connected in parallel. Its operation frequency was centered at 3.25GHz and 3.75GHz with 500-MHz-wide channels. The HTS diplexer operated at 77 K shows excellent performance. The insertion loss in the pass-band is less than 0.8 dB and the rejection between per channel is greater than 30dB. In comparison with the conventional diplexer, the HTS diplexer offers more than 2dB improvement in insertion loss performance and 3/4 volume reduction. This design concept can be applied to the design of HTS multiplexer and the future HTS ESM channeliser systems.     

高温超导滤波器研制

设计并制作了中心频率为2 007.5MH z,带宽为15MH z的6阶T l2B a2C aCu2O8高温超导微带滤波器.采用在谐振器之间插入微带条来微调耦合间距的办法,提高了设计的精确度.实测结果表明滤波器的最小插入损耗为0.25 dB,带外抑制约60 dB,带内波纹为0.16 dB,中心频率、带宽以及边带陡峭度等都与仿真结果吻合较好,验证了设计与制作的一致性.     

Space qualification mechanical tests of HTS filters for satellite application

High performance high-temperature superconducting （HTS） filters have been designed and constructed for satellite application. The filters are actually a superconducting integration of an 8-pole band-pass filter with an adjustable band-stop filter onto a single piece of LaAIO3 substrate （with dimension of 0.5x45x20 mm3）. Typical results of the filters, i.e., Filters A （made by YBCO） ＆ B （made by TBCCO） will be reported. The measured responses of Filter A showed excellent specifications, e.g., an insertion loss less than 0.1 dB, a return loss better than -22.5 dB in pass-band, band-edge steepness greater than 12 dB/MHz and out-of-band rejection at a certain band deeper than -110 dB. To satisfy the requirement of rocket launch and space operation, three filters of the above design have undergone mechanical environmental simulation tests for space qualification. Detailed analysis of the response curves of Filter B measured before and after the tests showed that no noticeable change in the performance can be found. All the filters passed the rigorous ground simulation tests, which is the first time in China for HTS devices and provided a solid foundation for satellite applications of high-temperature superconductors in the near future.     

Second generation YBCO coated conductors： A review

The advance in first generation Bi-2223 HTS wire has enabled the demonstration of superconducting power cables, magnetic energy-storage devices, transformers,fault current limiters and motors. However, the low irreversibility field (H^*) prevents application of Bi-2223 at 77 Kin any significant field. Worldwide activities are therefore,focused on developing a second-generation HTS technology based on YBCO, for which H^* (77K)-7 T. In this paper, we discuss the status and commercial prospects of second generation HTS wire technologies. In addition, we review the recent results and discuss the prospects of future applications.     

High temperature super-conducting (HTS) C-band oscillator with phase noise of -134 dBc/Hz

A high Q HTS cavity resonator with resonating frequency fo = 5.624 GHz was fabricated using high quality HTS film and high purity sapphire. The unloaded quality factor of the HTS resonator was as high as Qt = 1.09×106 at the nitrogen temperature, 77 K. A HTS local oscillator combining the high Q cavity resonator with a C-band low noise GaAs HEMT amplifier was then designed and constructed.The phase noise of the oscillator, measured by a HP 3048A noise measurement system, is -134 dBc/Hz at 10 kHz offset when the temperature is 77 K. This result is close to the best level reported by other groups in the world.     

高温超导电缆的磁场计算

以螺旋电流导体磁场分析为基础，推导了超导输电电缆各层导体自感和层间互感，以及各层导体所承受的不同方向的磁场强度计算公式，并给出算例，这些计算方法是优化超导电缆层间分流均匀性，分析超导电缆交流损耗的基础．     

低功耗、高线性CMOS可编程放大器

针对接收机前端中可变增益放大器需要高线性处理大信号的问题,分析了使用源极退化电阻以及跨导增强电路的放大器线性度;设计了使用改进型跨导增强电路的放大器。它具有更强的跨导增强能力,同时减小了输入M O S管跨导由于漏源电压变化产生的非线性失真。提出了一种对称的可变电阻结构,它降低了M O S管开关带来的非线性。仿真结果表明,放大器在3.3V电源电压下直流功耗为1.5mW,在1~10MH z带宽、3~24 dB增益范围内,差分输出信号峰峰值为3.3V时,总谐波失真低于-60 dB。     

Development of high-temperature superconducting filters operating at temperatures above 90 K

This paper represents the development of a high temperature superconducting （HTS） filter, the highest operating temperature of which is up to 93 K. The filter is designed for S band with 4% fractional bandwidth and fabricated using thallium-barium-calcium-copper oxide （TI2Ba2CaCu2O8） thin films. At 93 K, the measurements of the filter show that the insertion loss in the passband is less than 0.22 dB, the return loss is better than 20 dB, and the out-of-band rejection is more than 80 dB. The analysis on the characteristics of the filter operating at different temperatures shows that the filter can work well at temperatures around 90 K. The temperature of 93 K is the highest among the previous reports for HTS filters. The result reported in this paper is significant for HTS filters to be used in the field of microwave communication requiring high sensitivity.     

一种用于脉冲超宽带接收机的0.18-μm CMOS工艺的高增益检波器

设计了一个用于非相干脉冲超宽带接收机的0.18-μm CMOS工艺的能量检波器.该检波器包含了输入匹配模块、平方电路、翻转电压跟随器-电流检测电路、跨导级以及输出缓冲器.平方电路运用饱和区晶体管的平方律特性对输入差分信号进行平方,所得到的输出电流由翻转电压跟随器-电流检测电路转换成电压.跨导级对该信号进行放大并积分得到所接受的能量.测试结果可以看出,当输入信号的峰峰值超过60mV时,在高达300 MHz的频率下检波增益可以达到10 dB.而最小检测幅度为13 mV,此时的检波增益为5 dB.在移除输出缓冲器之后,输出脉冲的幅度将增加一倍.不计及测试焊盘,芯片面积为0.23 mm×0.3 mm.电路由一个1.8 V的电源供电,核心电路电流为3.5 mA.该检波器已成功应用于开关键控方式的接收机以实现高速宽带通信.     

高温超导线圈的交直流冲击安全性仿真

超导磁体的稳定性和线圈产生的热量在线圈中积累有着很重要的关系,因此超导线圈在大电流冲击下的热稳定性问题的研究就有着典型意义.本文建立一个载流高温超导线圈的温度分布随时间的推移数值模型,并采用差分法模拟线圈在大电流冲击下的发热和传热情况.研究发现超导线圈的散热能力和热容是决定其能否工作在很高温度下的决定性因素.     

Design and research of torque tube used in HTS motor

In order to improve the overall performance of high temperature superconducting （HTS） motor, a radial connection torque tube with high strength and low thermal leakage has been designed. Firstly, fiberglass epoxy composite is chosen as con- struction material. The structural size of the torque tube is obtained by means of load analysis and theoretical calculation. Secondly, thermal leakage of the torque tube is calculated with both theo- retical method and 3D finite-element analysis （FEA）. According to the result of the thermal analysis and mechanical loads, the struc- tural stresses of the torque tube are also obtained by FEA method. Lastly, a low temperature test platform is developed to verify the strength and the thermal leakage of the torque tube. The results show that the maximal shear stress of the torque tube is 24.3 MPa and thermal leakage of torque tube is 10.5 W, which satisfy the design requirements of the HTS motor. The torque tube also works in good condition at full-power and full-torque testing of the motor. The design method is also applicable for other similar design of torque tube in other applications.     

液晶空间光调制器在HTS中的应用研究——快速精确的解码方法

研究了液晶空间光调制器(LC—SLM)作为固定不动的编码模板应用于阿达玛变换光谱仪(HIS)，提出了快速精确的解码方法，给出了由液晶空间光调制器编码模板所带来的均方根信噪比的改善。     

一种用于UWB接收端的带通滤波器分析与设计

采用0.18 μm工艺设计1个用于UWB接收端的4阶切比雪夫有源RC带通滤波器.给出1种有损积分器直流增益补偿策略,从而减小滤波器对运算放大器直流增益的要求.同时,采用1种数控电阻的方式实现通带增益的调节.仿真结果表明:所设计的滤波器在通带增益为0dB时,通带纹波增益为0.112 dB,下-3 dB频率为156 kHz,上-3 dB频率为259 MHz,带宽为258.844 MHz;频率为500 MHz处的信号衰减为28.25 dB,频率为792MHz处的信号衰减为45.16dB,完全符合UWB接收端对带通滤波器的性能指标要求.     

一种用于“北斗”卫星导航系统的小型化微带贴片天线

基于“北斗”天线小型化的考虑，利用高介陶瓷基板（εr=16）来设计“北斗”卫星导航系统微带贴片天线，该天线采用切角结构，同轴线馈电方式，工作在“北斗”一代的S频段（2 492 ± 5 MHz,右旋圆极化）。采用Ansoft公司三维电磁仿真软件HFSS进行仿真分析，数值仿真结果表明： S11<-10 dB的阻抗带宽为62 MHz，3 dB极化轴比带宽为15 MHz；采用矢量网络分析仪对天线实物进行性能测定，实测结果表明，S11<-10 dB的阻抗带宽为66 MHz，3 dB圆极化轴比带宽为12 MHz，仿真结果与测试结果基本吻合，天线性能良好，满足“北斗”接收天线设计要求。该天线在满足北斗接收天线的性能的同时，由于采用高介陶瓷作为基板，使得其与传统天线相比，尺寸缩减了75%，具有一定的应用前景。     

低频声表面波器件的设计与制作

采用数字傅里叶变换技术设计并制作了一个中心频率为44MHz，1dB带宽为8MHz，带外抑制大于60dB，插损小于28dB的带通滤波器．发射和接收叉指换能器均采用数字傅里叶变换技术．整个声表面波滤波器的制作工艺流程是：基片抛光打磨、清洗、镀膜、匀胶、光刻、腐蚀和显影．实验结果分析表明此带通滤波器满足各项指标．     

A 23 GHz high-temperature superconducting microstrip filter for radio astronomy

This paper reports a 6-pole high-temperature superconducting （HTS） microstrip bandpass filter for radio astronomy applications. The filter has a center frequency of 23 GHz and a bandwidth the 2 GHz. We have made many efforts, such as adopting 0.25-mm-thick substrate, carefully designing the housing box and filter layout, to solve the problems in realizing a K-band planar filter. A special straight-line half-wavelength resonator （center-widen resonator） was also designed to reduce the insertion loss of the filter. The measured results showed a midband insertion loss of 0.11 dB with a ripple of 0.4 dB, and a return loss better than 11.5 dB. Good agreement was obtained between simulated and measured results.