Parametric oscillations in an oscillating circuit utilizing negative resistance

The paper deals with parametric phenomena in a non-linear oscillating circuit with negative resistance. The differential equations of the parametric excited circuit. for the case where the self-oscillations' amplitude is smaller than the amplitude of the pumping signal, reduce to the equations of Hill and are solved by an original method (Samoylo and Spasov 1970). In an investigations of the transient and Steady-state regimes the real non-linearity of the reactive element in the oscillating circuit is considered. The mode of forced oscillations and the resonance of the second and third subharmonies of the pumping signal are discussed. The experimental results agree well with theory

The results given in the paper may be of interest in an investigation of oscillating circuits, utilizing semiconductor elements with negative resistance : tunnel diodes, Gunn diodes, avalanche transit-time diodes, etc     

New insight into subharmonic oscillation mode of GaAs poweramplifiers under severe output mismatch condition

This paper provides new insight into the cause of subharmonic generation in GaAs MESFET power amplifiers under severe output mismatch conditions. A nonlinear modeling methodology is developed to identify the root cause of subharmonic oscillations and provides a means to implement circuit techniques to suppress this mode of oscillation without degrading the desired power amplifier performance. The primary mechanism for low-order subharmonics generated as a result of large signal drive and severe output mismatch is shown to be parametric. This modeling-based technique is enabled through the use of a time domain MESFET model which achieves excellent convergence by avoiding the discontinuity in high-order derivatives that is typical of implementations that use conditional functions. This technique provides the design engineer for the first time the ability to determine the large signal parametric stability of a power amplifier operating into a severe mismatch and implement circuit solutions prior to MMIC fabrication     

In-Line Signal Circuit for Broad-Band Parametric Amplifiers

A new double-tuned parametric amplifier signal-circuit configuration and a method for its experimental optimization is described. A new in-line signal circuit, which is adapted from a quarter-wave-coupled bandpass filter, is intended for use at higher microwave and millimeter-wave parametric amplifiers (paramps). It is shown that, using this signal circuit, a broader flat-gain response can be obtained as compared with the conventional double-tuned signal circuit with broad-banding stub placed multihalf-wavelength apart from the diode. To suppress the spurious response, a semilumped approximation is applied in the design. Finally, a "cold and hot" test method to optimize the double-tuned signal circuit is introduced.     

0.1 THz鳍线单平衡式基波混频电路研究

研究了一种基于石英基片的0.1 THz频段的鳍线单平衡混频电路,混频电路的射频和本振信号分别从WR10标准波导端口通过波导单面鳍线微带过渡和波导微带探针过渡输入,中频信号通过本振中频双工器输出。这是一种新型的混频电路形式,与传统的W波段混频器相比,混频电路可以省略一个复杂的W波段滤波器,具有电路设计简单、安装方便的特点。该电路使用两只肖特基二极管通过倒装焊工艺粘结在厚度为75 m的石英基片上,石英基片相对传统基板,可以极大提高电路加工精度。在固定50 MHz中频信号时,射频90~110 GHz范围内,0.1 THz混频器单边带变频损耗小于9 dB。     

The Hybrid Parametric Amplifier

This paper calculates the gain and noise performance of a new version of the parametric arnplifier in which the signal circuit is part of an artificial transmission line while the idler circuit is resonant. A particularly useful property of this type of parametric amplifier is absence of oscillation with increasing pump power.     

Hybrid parametric amplifier

The letter proposes a hybrid parametric amplifier in which the signal circuit is a travelling-wave structure and the idling circuit is resonant. A simple expression for the available gain per section is calculated together with typical circuit values.     

Parametric amplification and oscillation using an inverted maser material

Experimental results are reported demonstrating the possibility of achieving parametric gain in an inverted paramagnetic medium. In this case the parametric pump frequency may be lower than the signal frequency. The authors used chromium-doped rutile as the active material, a pump frequency of 150 MHz, and a signal frequency of 4.25 GHz. The parametric effect is strongly supported by adjusting the idling circuit for high master gain.     

三波混频光参量放大器中带宽的研究

对三波混频光参量放大器中参量过程的带宽进行了研究 ,给出了具有普遍意义的参量带宽和增益带宽的数学显式模型 ,这些模型引入了非线性晶体长度、群速、色散、增益系数等变量对带宽的影响 ,依据这些模型对影响参量放大器中带宽的各种因素进行了模拟计算、分析和比较 ,结果表明 :信号光和闲置光之间的群速度失配是影响参量放大过程带宽的主要因素 ,当信号光和闲置光之间实现群速度匹配时 ,可以获得最宽的带宽 ,因此对于任何三波混频光参量放大器中的参量过程 ,都可以通过选择合适的非共线角、非线性晶体长度、抽运光强度来获得最宽的带宽 ,从而支持超宽带增益     

毫米波宽带高中频单平衡混频器设计与实现

针对毫米波宽带通信、雷达和测试仪器领域的应用需求,提出一种E波段宽带高中频(IF)单平衡混频器。射频(RF)及本振(LO)信号通过多分支宽带加宽波导正交耦合器输入,通过鳍线过渡结构将信号从波导传输模式过渡到微带模式,并提供宽带中频信号及直流接地回路;中频输出低通滤波器可有效抑制LO及RF信号,并为其提供等效接地回路。利用肖特基二极管的非线性实现混频,并通过微带匹配电路最终实现宽带低损耗混频效果。混频器采用57.6、62.4、67.2 GHz 3个点频本振,将67~85 GHz的射频信号分段下变频至9.4~17.8 GHz的中频范围内。测试结果表明,在67~85 GHz射频频率范围内,射频输入功率为-15 dBm,本振输入功率为12 dBm时,混频器变频损耗为7.1~10.1 dB,对组合杂散的抑制在36 dBc以上。     

数字式单边带混频

本文主要分析用正交信号实现单边带混频电路,并阐述其优越性.     

An Extension of the Mode Theory to Periodically Distributed Parametric Amplifiers with Losses

For the extension of the mode theory of the Iossless periodically distributed parametric amplifier to the Iossy case, a "conjugate circuit" is introduced in this paper. The conjugate circuit is an imaginary circuit which is obtained in the pass band by replacing each resistance in the original circuit with the negative resistance of the same maguitude. The orthogonality properties between the modes of the original circuit and those of the conjugate circuit are derived. The power gain and the noise figure of the amplifier are calculated, showing the usefulness of this mode theory in accounting for the spreading resistance of the semiconductor diode.     

Design and Operation of Four-Frequency Parametric Up-Converters

A theoretical analysis of a four-frequency parametric-diode up-converter is presented, retaining both sum and difference frequencies generated by mixing of pump and signal. Upper and lower sideband up-converters are compared, and it is shown that the gain limitations of the former can be overcome by combination with the latter, without appreciable loss of stability. Three different parametric amplifier configurations utilizing this four-frequency mode of operation have been designed, fabricated, and tested. These designs utilize sum-frequency up-conversion from 400 to 9400 Mc., and have exhibited noise figures below 1.5 db, gain in excess of 12 db, and bandwidths greater than 8 Mc.     

自适应掩膜信号集成局部特征尺度分解及其应用

局部特征尺度分解（LCD）是为克服经验模态分解（EMD）中均值曲线构造的不足而提出的一种自适应信号分解方法,已被应用于机械故障诊断领域.但LCD存在与EMD类似的模态混叠问题,为此,基于均匀相位差掩膜信号构造,提出了自适应掩膜信号集成局部特征尺度分解（AMSELCD）,该方法不仅能够将一个复杂信号自适应地分解为若干个本征模态函数和一个剩余项之和,而且能够有效地解决LCD的模态混叠现象.通过仿真信号分析,将AMSELCD与现有多种抑制模态分解方法进行了对比,结果表明了所提方法的有效性和优越性.最后,针对滚动轴承和转子碰摩故障振动信号的调制特征,将所提AMSELCD方法应用于转子碰摩和滚动轴承的故障诊断,对比和实验分析结果进一步验证了所提方法的有效性和优越性.     

Method for eliminating mode mixing of empirical mode decomposition based on the revised blind source separation

Since mode mixing of empirical mode decomposition (EMD) is mainly caused by the intermittence and noise, we propose a novel method to eliminate mode mixing of EMD based on the revised blind source separation. To this aim, an optimal morphological filter is employed to eliminate the noise. As a result, the component of mode mixing caused by noise is suppressed. Furthermore, the de-noised signal is decomposed into different intrinsic mode function (IMF) components through the EMD algorithm. Since it is impossible to apply blind source separation to a single channel signal directly, the IMF component, which has mode mixing is chosen and reconstructed in the phase space. Following that, the equivalent hypothetical signals are obtained. Finally, an improved fixed-point algorithm based on independent component analysis (ICA) is introduced to separate the overlapping components. The analysis of simulation and practical application demonstrates that our proposed method can effectively tackle the mode mixing problem of EMD.     

Maximum Bandwidth Performance of Non- degenerate Parametric Amplifier with Single-Tuned Idler Circuit

The single-tuned bandwidth and limiting flat bandwidth of a nondegenerate reflection-type diode parametric amplifier is calculated. The amplifier has a broad-banding filter structure in the signal circuit and a single-tuned idler circuit. An experimental low-noise, wide-band Z-band amplifier is described, and measurement results are presented. The amplifier has a triple-tuned signal circuit and a single-tuned idler circuit and is pumped at 11.3 Gc. A nearly flat bandwidth of 23 per cent at 7 db gain and an effective input noise temperature of 70/spl deg/K at room temperature ambient and of 29/spl deg/K at liquid nitrogen (77/spl deg/K) ambient has been obtained.     

一种基于AD9857的信号发生器的设计

信号发生器是电路系统设计、测试的重要环节,也是电路课程相关实验的基本组成模块.现有的信号发生器硬件规模大.发生信号种类少,功能扩展需更改硬件电路,不能完全满足系统设计、测试和复杂实验需求.AD9857可工作于正变调制、单音、内插DAC等三种模式.内部集成DDS、DAC等模块,实现信号发生的基本硬件功能.对以AD9857为核心设计的基于计算机和基本硬件电路的信号发生器进行探讨,为信号发生器设计提供借鉴;为系统设计和测试.特别是为电路课程实验中信号源种类多的问题提供一种解决方案.     

一种基于自适应峰值电流检测的模式切换电路北大核心

在降压转换器中，为了在不同的负载情况下获得高效率，常采用的方法是在重载时使用脉冲宽度调制(PWM),在轻载时使用脉冲频率调制(PFM),因此需要模式切换信号去控制整个降压转换器的工作状态，同时模式切换信号也可以用于自适应改变功率级电路中的功率管栅宽，减小功率管的栅极电容，提高整体电路的效率。文章设计了一个自适应峰值电流模式切换电路，用于产生模式切换信号，其原理是监控峰值电流的变化，产生峰值电压，将峰值电压与参考电压进行比较，得到模式切换信号，以决定降压转换器是采用PFM模式还是PWM模式。仿真结果表明，在负载电流0.5～500 mA范围内，该电路可以在两种调制模式之间平稳切换，其峰值效率可提升到94%以上。     

共模抑制的渐变结构高速差分电路设计

本文构建了一种拐角分段阻抗控制的渐变结构高速电路差分线,采用了 HFSS 三维电磁仿真软件对差分信号进 行了建模分析。 对混模 S 参数的仿真分析结果表明:对比平行结构的差分信号设计方式,所提出的添加 GND 孔渐变结构 差分信号在 10 GHz 范围内差模转差模增大了 58. 7%,差模转共模减小了 38. 3%。 通过对实物测试显示:添加 GND 孔渐 变结构差分线的 Sd2d1 参数和 Sc2d1 仿真结果和实测结果具有很好的一致性,差分电路差模转共模得到了有效地抑制,对应 的差分信号传输效率得到了提升。 电场分布表明:渐变结构设计方法极大改善了差分电路转角位置电场分布,避免了差 分电路传输线间电场聚集,使差分信号共模噪声和反射损耗减小,实现了高速差分信号传输的连续性。     

A Nondegenerate Traveling-Wave Parametric Amplifier

The traveliig-wave parametric amplifiers reported to date are not sufficiently competitive to ensure their use in advanced RADAR systems. The major hindrance is the relatively high-RADAR noise figure which is due to the fact that the signal and idler frequencies are about equal; i.e., the amplifier is degenerate. Initial experiments directed toward obtaining a nondegenerate microwave traveling-wave parametric amplifier are reported in this paper. A promising circuit has been developed and an S-band nondegenerate amplifier has been built and tested. In the first part of the paper the circuit is described and the experimental results are given. The second part of the paper describes procedures which have proved useful in the development of the circuit and which should also prove useful in future investigations.     

32×32双色红外探测器同步读出电路设计

双色（中短波）同步工作模式的红外探测器,其输出光电流信号为中波信号和中短波混合信号。文中提出了一种电压信号相减的电路结构,可在中波和中短波信号同步积分后,将两个波段的积分电压信号进行相减,得到单独的短波信号,实现信号分离的过程,并对32×32规模的电路进行了仿真验证,电路在仿真中有良好的性能。