超导亚毫米波阵列振荡器的扰动模拟

本文系统地研究了超导亚毫米波阵列振荡器。首先介绍了约瑟夫森结阵列振荡器的基本原理 ,然后根据原理引出超导亚毫米波阵列振荡器的模型 ,最后 ,根据约瑟夫森原理 ,对超导亚毫米波阵列振荡器的模型进行了模拟和分析 ,仿真得出了振荡器各项参数值 ,并给出了相位锁定的条件     

约瑟夫森结的电路模型及其在超导电子学中的应用

为方便约瑟夫森结及其相关电路的仿真研究,根据约瑟夫森方程首次提出了约瑟夫森结的电路模型,给出了具体的电路原理图,并进行了封装.利用这个模型可以对约瑟夫森结的相关特性进行深入系统的仿真研究,这样不必自己编写程序对系统的微分方程进行数值求解,大大提高了工作效率.利用这个模型,对约瑟夫森结的混沌行为、相位锁定特性、RSFQ电路和SQUID进行了研究,结果说明了模型的正确性和实用性,模型的建立对于促进超导器件的相关研究具有一定意义.     

一种S波段压控振荡器级联的注入锁定

针对压控振荡器(VCO)阵列注入锁定电路复杂和规模受限问题,提出一种S波段VCO阵列级联的新方法。通过在多个VCO之间加入耦合网络,将传统的单级注入改进为级联注入锁定,并通过网络级联方式实现级联级数的扩展。各级VCO之间通过耦合网络实现级联,首级VCO通过信号源参考信号进行锁定,次级VCO耦合前级VCO射频输出端信号进行锁定,每级均通过VCO电压调谐端进行注入。注入信号可锁定VCO输出频率,改善每级VCO输出相位噪声。通过级间耦合的形式,实现了一个微波源锁定多个VCO的输出。设计加工了2种级联注入VCO阵列,VCO的输出频率与注入信号频率相同,各级VCO相噪保持一致,当源相噪为-107.28 dBc/Hz时,各级VCO的输出相噪保持一致,为-105 dBc/Hz。该注入锁定方式电路简洁且成本低,未来有望应用在相控阵中。     

基于FDTD的约瑟夫森结与超导传输线协同分析方法

为实现高性能处理器,超导RSFQ（快速单磁通量子）电路被提出.该电路主要由超导约瑟夫森结和超导无源传输线组成,对其建模分析是超导RSFQ电路设计的基础.本文提出了基于FDTD（时域有限差分）的约瑟夫森结与超导传输线的协同分析方法.该方法采用FDTD数值方法求解超导传输线的电报方程.在超导传输线与约瑟夫森结交界处的非线性边界条件上,采用了Newton-Raphson迭代算法.数值结果表明,本文提出的约瑟夫森结和超导传输线的协同分析方法与WRspice仿真软件相比具有相同精度,且运算效率显著提高.     

含约瑟夫森结电路的特性分析和研究

提出了超导约瑟夫森结模型(并联电阻—电容结模型)，给出了约瑟夫森效应的一些重要结果。在分析约瑟夫森结电路方程时，研究了其中出现的混沌特性和子台阶现象。计算获得的结果对混沌数字通信和超导电子学的应用将起到重要作用。     

矩形耦合本振阵列接收波束形成

分析了耦合振荡器阵列的波束接收原理,以二维矩形耦合振荡器阵列为本振阵列,推导了产生均匀平面相位分布的控制方法,确定了波束形成的相位加权矢量,并通过仿真验证理论分析结果,为耦合振荡器阵列在天线接收技术的应用提供理论参考.     

双单元振荡器型天线阵的变模分析

本文证明了双辐射耦合振荡器型阵列天线系统性能是单元之间和相互耦合强度手函数。天线性能的预测要求辨别正确的阵列模式，这样，给出了一个简单的方法就是通过这些模式的稳定性辨识，分析相同的有源振荡器型天线之间辐射耦合，得到各种工作模式下的阵元的锁定频率和单独振幅的明确的公式。     

超导微波源的仿真、设计与制备

本文主要介绍了采用超导约瑟夫森结实现的超导微波源的基本原理及实现方法。文中我们通过电路仿真得到了 输入为直流信号，输出为幅值可调的4.2GHz 微波信号，然后根据相应仿真参数绘制了芯片版图，并对实验室原有的自对 准剥离工艺进行了改进，完成了超导微波振荡器的制备，为将来利用超导材料实现具有实用价值的太赫兹源奠定了理论 以及实验研究基础。     

三角形耦合本振阵列天线波达方向估计

提出以对称三角形耦合振荡器阵列为本振阵列,分析了耦合本振振荡器的相位控制原理,给出耦合本振阵列相位控制方法,推导了耦合本振阵列锁相同步时,形成均匀的线性相位分布,且阵元间的相移只与边界上振荡器的振荡频率有关。利用耦合本振阵列形成均匀相位分布的这一属性,调整耦合本振阵列边界上的振荡器振荡频率,改变耦合本振相邻阵元的相移,实现波达方向估计。同时对三角形耦合阵列的稳定过程、波达方向估计进行了计算机仿真,验证了理论分析结果。     

一种菱形结构二维耦合振荡器阵列的设计与同步实验

研究了菱形结构二维耦合振荡器阵列的相位动力学方程,对4×4阵列稳定过程进行了仿真研究,设计并制作了4×4单元耦合振荡器阵列及阵列相位差测量系统,实现了16单元耦合振荡器阵列的全局同步。     

Modeling of a quasi-optical Josephson oscillator

The authors have developed a computer model of a Josephson tunnel junction embedded in a general circuit with frequency-dependent impedance using the harmonic balance method. This model has been applied to the analysis of a two-dimensional Josephson junction array with integrated coupling structures, called a quasi-optical Josephson oscillator. Simulations are done for a junction with dipole, slotline, and bow-tie antennas. The results show that the junction with a bow-tie antenna gives the best performance, and the output power from an array of 4000 junctions can reach 25.7 μW at a frequency as high as 1091 GHz for niobium junctions deposited on a 0.207-mm-thick quartz substrate     

Niobium-based integrated circuit technologies

Metallurgical and electrical properties of Nb and NbN films for use as Josephson junction electrodes and wiring layers are investigated. The crystallographic and superconducting properties necessary for Nb-based integrated circuit processes are clarified. Tunnel barrier structures of NbN-Nb oxide-NbN (Pb alloy) and Nb-Al oxide-Nb Josephson junctions have been analyzed and correlated with junction characteristics and critical current uniformity. It was found that the surface structure of a base electrode should be smooth to ensure that Josephson junctions have low leakage current and uniform critical current distribution. New types of Josephson junctions with artificial tunnel barriers such as amorphous Si or Mg oxide are reviewed. A variety of Josephson junction structures or processes have been developed for Nb-based Josephson integrated circuits in order to improve circuit performance. These include junction miniaturization, planarization, and stacked junction structures. These structures are mainly intended for Nb-Al oxide-Nb Josephson circuits. The Nb-Al oxide-Nb Josephson junction technology is by far the most advanced and has been used in logic and memory circuits, for example a 4-bit×4-bit parallel multiplier, a Josephson logic gate array, a 16-bit arithmetic logic unit, a 4-bit microprocessor, and 1-kb and 4-kb memory circuits     

Perturbation simulation for two-dimensional Josephson junctionarray with resonator structure

A numerical perturbation method to simulate phase-locking behavior for resonator structure-type Josephson junction arrays is introduced. Simulations are completed for one-dimensional parallel, one-dimensional series, and two-dimensional arrays showing new and interesting phenomena. The simulation results provide a clear view of the processes by which the Josephson junctions become mutually phase-locked. Optimum structure parameters for oscillator circuit designs are determined using these simulation results     

Microwave theory of Josephson oscillators

In this paper, we deal with a model of a specific Josephson microwave circuit, that of a Josephson oscillator, and show that the RF behavior of a real Josephson oscillator may be predicted from a knowledge of the experimentally measured microwave circuit parameters, the junction critical current, and junction shunt resistance. Based on observations made with an electronic analog, we present an approximate analytical method for calculating the junction impedance or, rigorously speaking, the appropriate single sinusoidal-input describing function. Emphasis is placed on the proper use of the impedance, for example, in calculating the operating point and the expected output power of the oscillator. The circuit model used is that of a junction, described by the resistively shunted junction model, coupled to a seriesLCRresonance. Further confirmation of the validity of the circuit-theory approach is obtained by using the injection-locked oscillator theory of Kurokawa to predict the in-lock amplitude variation of a Josephson oscillator exposed to a weak synchronizing signal. Experimental data describing the amplitude variation and output power of an oscillator consisting of a point-contact junction placed in a 9.72-GHz coaxial resonator are presented. The data demonstrate the reasonable agreement obtained when the measured critical current and shunt resistance are used with the analytical expression for the junction impedance and the circuit theory to predict the RF behavior of a Josephson oscillator. Circuits more complex than our specific example may be handled by means of describing function techniques recently developed in the area of nonlinear solid-state microwave devices.     

PHASE－LOCKED 2－D JOSEPHSON JUNCTION ARRAYS AS SUBMILLIMETER OSCILLATORS

This letter presents the results of numerical simulations for phase-locked 2-D Josephson junction array oscillator.The simulation result shows that the junctioons of 2-D array can mutually phase-locked in a considerable area if the parameters can be carefully selected.The oscillators are formed with up to 33 identical Nb/AlOx/Nb junctions,and the junctions are connected with Nb microstrip resonators.Optimum structure parameters for ocsillator circuit design can be obtained with these simulation results.     

Low noise submillimeter SIS receiver with niobium nitride quasiparticle tunnel junctions

We have developed and tested a submillimeter waveguide SIS mixer with NbN-MgO-NbN quasiparticle tunnel junctions. The two junction array is integrated in a full NbN printed circuit. The NbN film critical temperature is 15 K and the junction gap voltage is 5 mV. The size of the junctions is 1.4 × 1.4 µm and Josephson critical current density is about 1.5 KA/cm² resulting in junction R_NωC product about 40. The inductive tuning circuit in NbN is integrated with each junction in two junction array. A single non contacting backshort was tuned at each frequency in the mixer block. At 306 GHz the minimum DSB receiver noise temperature is as low as 230 K. The sources of the receiver noise and of the limits of the NbN SIS submillimeter mixer improvement are discussed.     

Analysis of injection-locked antenna array including mutual coupling effects

In this paper, the injection locking performance analysis of dipole antenna array with each element loaded with a two-terminal oscillator is presented. The analysis is based on the nonlinear model of oscillator and the linear model of antenna array considering mutual coupling effects. The locking range of injection signal and the array radiated power are obtained by solving an equivalent multiport network. In general, the solutions include stable and unstable solutions. The Routh-Hurwitz stability criterion is then applied to remove the unstable solutions. Numerical results show that the array performance such as frequency locking range and radiated power by taking into account the array mutual coupling effects is quite different from that of an isolated antenna element. In addition, the influence of antenna element spacing upon array locking parameters in this paper is found to be consistent with other existing theories.     

A compact single layer injection-locked linear scanning array

A compact, single layer, CPW-fed, patch scanning array architecture using injection locking at 9.83 GHz is presented. The patch antennas are printed on the front side of the substrate while the electronics are situated at the back side leading to a simple and compact design. The unit element for the array is a self oscillating active patch antenna with a GaAs FET centered behind the patch for tight packing. The feedback for the oscillator is provided through electromagnetic coupling using a twin-slot arrangement behind the patch. A low power control signal is injected through parasitic coupling at the CPW side of the circuit. Phase shifting of the elements is achieved by electronically adjusting the gate voltage of the GaAs FETs. A scan range of -12°- +9.5° is obtained for a four element prototype array     

Radiating and scattering analyses of a slot-coupled patch antennaloaded with a MESFET oscillator

In this paper, radiating and scattering analyses of a slot-coupled patch antenna loaded with a MESFET oscillator at free-running and injection-locked states are presented. This arrangement is a basic module of an injection-locked active array. With a small injection signal applied directly to the oscillator in a transmission-type mode or indirectly through a patch antenna to the oscillator in a reflection-type mode, the oscillator loaded antenna then becomes an injection-locked active antenna (ILAA) within the locking range. Simulation results yield the oscillating frequency and radiating power at the free-running state and the locking range and radiating power at the injection-locked state. Both radiating and scattering analyses are performed in a unified approach for the transmission-type and reflection-type operation modes of ILAA. Experiments show the validity of the developed theoretical analyses. These results can be applied in the ILAA array design     

A subharmonic self-oscillating mixer with integrated antenna for60-GHz wireless applications

A balanced integrated-antenna self-oscillating mixer at 60 GHz is presented in this paper. The modal radiation characteristics of a dual-feed planar quasi-Yagi antenna are used to achieve RF-local oscillator (RF-LO) isolation between closely spaced frequencies. The balanced mixer is symmetric, inherently broad band, and does not need an RF balun. Pseudomorphic high electron-mobility transistors are used in a 30-GHz push-pull circuit to generate the second harmonic and a 30-GHz dielectric resonator was used to stabilize the fundamental oscillation frequency. This allows the possibility of building a balanced low-cost self-contained antenna integrated receiver with low LO leakage for short-range narrow-band communication. Phase locking can be done with half of the RF frequency. The circuit exhibits a conversion loss less than 15 dB from 60 to 61.5 GHz, radiation leakage of -26 dBm at 60 GHz, and IF phase noise of -95 dBc/Hz at 100-kHz offset