Simulation Investigation of Millimeter Wave Varactor-tuned Transmission Cavity-stabilized Oscillator

A new circuit configuration for millimeter wave varactor-tuned transmission cavity-stabilized oscillator has been proposed in this paper. Compared to conventional varactor-tuned reflection cavity-stabilized oscillator, in this configuration, a high quality factor transmission cavity directly coupled to varactor diode is employed to improve the performances of the oscillator. The operation frequency of this oscillator can be tuned by varying the resonant frequency of the transmission cavity through changing bias voltage of the varactor diode. An equivalent circuit model for the oscillator has been presented in order to theoretically investigate the performance characteristics of the oscillator. On the basis of this model, electrical tuning characteristics have been studied. Mode jumping phenomena during electrical tuning process have been analyzed for obtaining stable operations of the oscillator. The analytical formulae of quality factor and efficiency have been derived in terms of relevant circuit parameters. Particular emphasis has been paid on several circuit parameters which have a substantial impact on circuit performance. Some design considerations have been pointed out according to the simulation results, which are useful to the design and fabrication of this type of oscillators.     

Theoretical Study of Millimeter Wave Harmonic Oscillator Stabilized with a Transmission Cavity

An equivalent circuit model of millimeter wave second harmonic oscillator stabilized with a transmission cavity has been proposed for constructing analytical formulations between performance parameters of the oscillator and parameters of the circuit. The model consists of an equivalent circuit of fundamental wave and that of second harmonic wave. Each of the circuits comprises circuit models of main cavity, transmission waveguide, and transmission cavity. Absorbing material placed between the transmission waveguide and the transmission cavity can suppress additional resonances originated from transmission cavity. The behavior of the second harmonic oscillator can be effectively described by the circuit model. Furthermore, based on this model, mechanical tuning characteristics have been studied at first, and then analytical formulas for quality factor and efficiency depending on circuit parameters have been derived. The circuit parameters can be conveniently extracted by electromagnetic field simulation. Hence the formulas exhibit both compact form and enough accuracy. Thereafter, general rules of performance parameters varying with circuit parameters have been deduced for the harmonic oscillators. Then some design considerations have been derived according to the corresponding analysis. The equivalent circuit model is useful for designing and adjusting millimeter wave second harmonic stabilizing oscillator with a transmission cavity.     

Millimeter-Wave (W-Band) Quartz Image Guide Gunn Oscillator

Dielectric image-guide Gunn oscillator using fused quartz as the guide material has been investigated at frequencies around 94 GHz. Computer-controlled CO/sub 2/ laser cutting of quartz to the designed image-guide patterns has also been achieved. A resonant disk and pin bias circuit was used to tune the oscillator to an output power of 5 mW at the oscillation frequency of 94.2 GHz. An electronic frequency tuning of 350 MHz was measured with the oscillation characteristics similar to waveguide cavity oscillators. By varying the bias circuit disk and pin parameters, the Gunn-oscillator tuning characteristics have also been recorded for the future circuit performance optimization.     

A Frequency Tuning Method for a Planar Inverted-F Antenna

A novel method is presented for electrically tuning the frequency of a planar inverted-F antenna (PIFA). A tuning circuit, comprising an RF switch and discrete passive components, has been completely integrated into the antenna element, which is thus free of dc wires. The proposed tuning method has been demonstrated with a dual-band PIFA capable of operating in four frequency bands. The antenna covers the GSM850, GSM900, GSM1800, PCS1900 and UMTS frequency ranges with over 40% total efficiency. The impact of the tuning circuit on the antenna's efficiency and radiation pattern have been experimentally studied through comparison with the performance of a reference antenna not incorporating the tuning circuit. The proposed frequency tuning concept can be extended to more complex PIFA structures as well as other types of antennas to give enhanced electrical performance.     

Varactor-tuned integrated Gunn oscillators

Electronic tuning of Gunn diodes in hybrid integrated circuits has been studied. Microstrip transmission lines were used to form resonant circuits into which a Gunn diode and a varactor diode were mounted to provide the microwave power and frequency tuning, respectively. Basically, two types of circuits have been investigated. The first is a half-wavelength open-circuited microstrip `cavity' with this transmission line and the varactor diode attached between the end of the cavity and an RF ground. The second is a lumped LC circuit in which the inductance of a short high-impedance microstrip line is resonated with the lumped capacitance of the varactor diode. The latter circuit provides a tuning range of over 10 percent at 7.5 GHz. The power output varies within 2 dB in the tuning range.     

A novel approach in calculating V-I curves of a DC-SQUID coupled toa planar input coil

The influence of a planar input coil on the V-I characteristics of a dc-SQUID (superconducting quantum interference device) has been analyzed by means of computation and experimental investigation. An extended electrical model of the input coil based on transmission lines has been proposed. The frequency behavior of this model has been validated with an expanded copper model. The V-I characteristics of DC-SQUIDs have been calculated with this extended circuit model using a SPICE-type circuit analysis program. The results have been compared with measurements of niobium dc-SQUIDs. In this paper the relationship between the V-I characteristics of the SQUID and the coupling impedance of the washer is demonstrated     

Numerical analysis on compliance and electrical behavior of multi-copper-column flip-chip interconnects for wafer-level packaging

This paper presents modeling and simulation results of a modified copper-column-based flip-chip interconnect with ultrafine pitch for wafer-level packaging, and the process and prototyping procedure are described as well. This interconnect consists of multiple copper columns which are electrically in parallel and supporting a solder bump. A simple analytical model has been developed for correlation between the interconnect geometry and the thermal fatigue life. In comparison to the conventional single-copper-column (SCC) interconnects, numerical analysis reveals that the multi-copper-column (MCC) interconnect features enhanced compliances and, hence, higher thermomechanical reliability, while the associated electrical parasitics (R, L, and C) at dc and moderate frequencies are still kept low. Parametric studies reveal the effects of geometric parameters of MCC interconnects on both compliances and electrical parasitics, which in turn facilitate design optimization for best performance. By using coplanar waveguides (CPWs) as feed lines on both chip and package substrate, a high-frequency (up to 40 GHz) S-parameter analysis is conducted to investigate the transmission characteristics of the MCC interconnects within various scenarios which combines various interconnect pitches and common chip and package substrates. An equivalent lumped circuit model is proposed and the circuit parameters (R, L, C, and G) are obtained throughout a broad frequency range. Good agreement is achieved for the transmission characteristics between the equivalent lumped circuit model and direct simulation results.     

声体波谐振器压控振荡器

声体波谐振器(FBAR)压控振荡器(VCO)技术探讨了高品质因数Q谐振器并实现宽频率调谐难题,完成了声体波谐振器MBVD模型参数建立、电路的选择与布局,以及最优化的设计与制作,尽量消除了FBAR与IC之间的引线产生的影响,克服了频率调整问题.研制了中心频率2.1GHz的VCO振荡器,研究结果表明,其输出功率为5～10 dBm,调谐范围为2.044‰,边带相噪为-143 dBc/1 Hz@1 MHz.     

A self-consistent large-signal analysis of a read-type IMPATT diode oscillator

A self-consistent one-dimensional large-signal analysis of a Read-type IMPATT diode oscillator has been developed which takes into account the device-circuit interaction. The circuit is modeled by a lumped-equivalent network representing the diode package, and a cascade of lossless transmission lines with discontinuity capacitances representing the coaxial-line cavity with tuning slugs. A particular voltage waveform across the semiconductor wafer is not assumed a priori. Instead, the voltage and current waveforms are determined iteratively until they satisfy the equations for both the diode model and for the circuit. The waveforms are found to be highly dependent upon the circuit in which the diode is embedded.     

数控跳频电调谐滤波器的设计

研究和设计了一种用于跳频通信系统射频前端的数控跳频电调谐滤波器,具有跳频点数多、跳频速度快等优点,并在不同的跳频点都具有良好的电参数指标。介绍了跳频接收机射频前端系统。对各种形式的电调谐滤波器进行性能分析．确定该数控跳频电调谐滤波器设计方案。介绍了该数控跳频电调谐滤波器电路和硬件电路的设计,包括其在ADS中的仿真模型和性能参数。最后对数控跳频电调谐滤波器进行测试,其性能指标完全达到系统设计要求．而且具有很强的实际应用性。     

方体压电谐振器共振频率电调谐技术

受环境因素的影响,压电谐振器的共振频率会发生漂移。调谐技术因采用特定的手段主动调节共振频率而得到广泛应用,但传统附加质量块、激光烧蚀等机械调谐技术费时费力,灵活性不好。针对方体压电谐振器该文提出了一种激励信号幅值调谐和直流调谐的电调谐方法,可精密调节谐振器的共振频率。设计了一种基于ZYNQ系列主控芯片的数字化测控电路,实现了振子扫频激励、输出信号的幅值相位检测,为激励信号幅值调谐和直流调谐提供了实验硬件平台。实验结果表明,激励信号幅值调谐的共振频率变化范围为347.850～348.000 kHz,直流调谐的调节范围为347.720～347.820 kHz。该技术为压电谐振器共振频率精密调节提供可靠的理论与实践途径。     

由RTD/MOSFET构成的压控振荡器的设计与实现

提出了一种基于负阻器件共振隧穿二极管(RTD)与MOSFET结合的新型压控振荡器(VCO),并利用了高级设计系统(ADS)软件对该振荡器的可行性进行了电路仿真,利用分立RTD、MOSFET器件实现了此种VCO,实际调频范围在20～26 MHz之间。RTD与三端器件的连接方式不同可呈现不同的调制I-V特性,这种调制特性对基于RTD的振荡电路的频率也会产生影响。通过深入研究这种调制对振荡电路频率产生的影响,得到多种不同于常规方法的电压控制频率方式,其中一些具有很好的线性度。因此该电路的研究对于RTD在高频、高速振荡电路中的进一步应用具有重要意义。     

Microwave properties and applications of negative conductance transferred electron devices

The transferred electron effect in epitaxial GaAs has been used to realize a semiconductor device which exhibits a stable negative conductance over a wide range of microwave frequencies and power levels. These devices have been used in conjunction with circulator coupled networks to design high-level wide-band transferred electron amplifiers which have a voltage gain bandwidth product in excess of 10 GHz for frequencies from 4.0 to about 16.0 GHz. Linear gains of 6-12 dB per stage and saturated output power levels in excess of ½ W have been realized. The physical and electrical properties of these devices are described with regard to the achievement of a stable negative conductance. The influence of several parameters (i.e., device temperature, bias voltage, circuit loading, etc.) is discussed with regard to device and circuit stability. Measurements of the terminal admittance of several typical devices as a function of the bias, input power, and frequency have been used to study their microwave properties. The large signal data are used to compute the relationship between the available device power and the magnitude of the negative conductance independent of the test circuit. This same measurement technique can provide a simulation of the performance of any nonlinear negative conductance, without the need for circuit design and load tuning. In addition, an analytical large signal model of the negative conductance has been used to predict the large signal performance of the active device (i.e., gain compression, conversion efficiency, etc.) in both oscillator and amplifier circuits.     

Fast wavelength-tunable multichannel switching using aself-injection seeding scheme

Wavelength-tunable switching among different channels in the range of hundreds of megahertz has been demonstrated by the self-injection seeding mechanism. The different wavelength components have been switched by sequentially feeding back the temporally separated cavity modes to the laser diode. The spacing between different wavelengths has been tuned by adjusting the electrical modulation frequency and the length of the dispersive fiber cavity. In addition to the spectral and temporal profiles, the switching characteristics such as the output pulsewidth, side-mode-suppression ratio, tuning rate, and the effect of the fiber length have also been investigated     

A complete small-signal equivalent circuit model of cooled butterfly-type 2.5 Gbps DFB laser modules and its application to improve high frequency characteristics

A small-signal equivalent circuit model of 2.5 Gbps DFB laser modules with butterfly-type dual-in-line packages has been proposed and verified using extracted parameters. Parameters related to the equivalent circuit have been extracted from measured S parameters using the modified two-port black box model. This model includes small-signal equivalent circuits of components used for 2.5 Gbps DFB laser modules such as DFB laser, coplanar waveguides, matching resistor, bonding wires, and thermoelectric cooler (TEC). From this equivalent circuit modeling, we show that calculated frequency characteristics of DFB lasers on submount and complete DFB laser modules are similar to their measured frequency characteristics, respectively. Based on this equivalent circuit model, we propose and demonstrate a method that can improve frequency characteristics of 2.5 Gbps DFB laser modules through both experiments and simulations.     

A Stabilized MIC Oscillator Using a Germanium Avalanche Diode (Short Papers)

A stabilized X-band oscillator using a germanium avalanche diode in a microwave integrated circuit (MIC) is proposed. The stabilization is achieved by coupling a transmission cavity to the resonant cavity in which an avalanche diode is embedded. A mode-jumping problem inherent in a coupled-cavity oscillator was solved coupling a third varactor-embedded low-Q cavity to the transmission cavity. As a result, single-mode oscillation in an MIC oscillater was successfully obtained. Varactor tuning can also be realized with as small a change in output power as 7 percent for a tuning range of 30 MHz. The experimental results and the theoretical analysis of the new stabilized oscillator are given.     

电调滤波器频率校准装置的设计与实现

针对电调腔体滤波器在确定中心频率时的调试、维护工作量大的问题,设计了辅助调节电调滤波器中心频率的装置——校频单元。给出了校频单元的设计模型,并对其进行了理论分析。在此基础上给出了校频单元的一种具体设计方案,并进行了实际电路设计。介绍了校频单元的具体实现方式,给出了实际电路的测试结果,并对结果进行了分析。分析表明,校频单元可以实现对电调滤波器中心频率的调节功能。目前校频单元已得到实际应用。     

一种基于传输线理论的新型GHz共模噪声抑制电路

基于传输线理论提出一种新型GHz宽阻带共模噪声抑制电路。利用双线传输线模型建立奇、偶模等效电路,在宽频带范围内准确预测了该电路结构的性能。实验结果表明:在1.9-4.5GHz频段内共模噪声抑制深度超-10dB,共模阻带相对带宽达81%;在dc-6GHz频段内差模插损小于3dB且差模信号群时延抖动较小,表明该结构可以很好地保证差模信号传输的信号完整性,性能优良。     

A simple circuit for FSK modulation of Gunn oscillators

A simple transmission cavity placed in the output transmission line of a CW Gunn oscillator can be adjusted to allow simple and cheap digital frequency modulation by bias modulation. Transition rates down to 10 ns have been demonstrated. A threshold switching voltage is required so that the circuit has noise immunity.     

一种微波滤波器的参数提取方法

在微波滤波器的计算机辅助调试技术中,必须要知道滤波器的状态参数。以往的方法主要是通过滤波器的耦合矩阵来求得它的状态参数,但计算起来相当复杂。介绍一种简单易行的提取滤波器状态参数的方法,该方法通过建立滤波器的等效电路模型,运用软件的优化拟合功能,从而提取出等效电路模型的参数值。实验证明,只要搭建的电路模型精确度较高,就能够迅速、准确地提取出滤波器的状态参数。