GaAs nonlinear transmission lines for picosecond pulse generation and millimeter-wave sampling

The GaAs nonlinear transmission line (NLTL) is a monolithic millimeter-wave integrated circuit consisting of a high-impedance transmission line loaded by reverse-biased Schottky contacts. The engineering of functional monolithic NLTLs is considered. Through generation of shock waves on the NLTL, the authors have generated electrical step functions with approximately 5 V magnitude and less than 1.4 ps fall time. Diode sampling bridges strobed by NLTL shock-wave generators have attained bandwidths approaching 300 GHz and have applications in instruments for millimeter-wave waveform and network measurements. The authors discuss the circuit design and diode design requirements for picosecond NLTL shock-wave generators and NLTL-driven sampling circuits.<>     

Picosecond optical sampling of GaAs integrated circuits

Direct electrooptic sampling is a noncontact optical-probing technique for measuring with picosecond time resolution the voltage waveforms at internal nodes within GaAs integrated circuits. The factors contributing to system bandwidth, sensitivity, spatial resolution, and circuit perturbation are discussed, as are the circuit requirements for realistic testing of analog and digital devices. Measurements of high-speed GaAs integrated circuits are presented, including time-domain waveform and timing measurements of digital and analog circuits and frequency-domain transfer function measurements of microwave circuits and transmission structures     

Millimeter-wave monolithic integrated circuit characterization by apicosecond optoelectronic technique

The characterization of microwave and millimeter-wave monolithic integrated circuits (MIMICs) using picosecond pulse-sampling techniques is developed with emphasis on improving broadband coverage and measurement accuracy. GaAs photoconductive switches are used for signal generation and sampling operations. The measured time-domain response allows the spectral transfer function of the MIMIC to be obtained. This measurement technique is verified by characterization of the frequency response (magnitude and phase) of a reference 50-Ω microstrip line and a two-stage K_a-band MIMIC amplifier. The measured broadband results agree with those obtained from conventional frequency-domain measurements using a network analyzer. The application of this optical technique to on-wafer MIMIC characterization is described     

Picosecond optics and microwave technology

Progress in the application of ultrafast optics to microwave and millimeter-wave techniques using picosecond photoconductors is reviewed. The generation, control, and characterization of pulsed and high-frequency waves using a frozen wave generator, an impulse excited resonator, and a spectral filter are discussed. A time-domain network analyzer which uses optoelectronic techniques for on-wafer monolithic microwave and millimeter-wave integrated-circuit measurements is described     

The optical response of epitaxial lift-off HEMT's to 140 GHz

We present measurements on the optical frequency response of epitaxial lift-off (ELO) 1.0-μm InP high-electron mobility transistors (HEMTs) to 140 GHz using electrooptic sampling and heterodyne techniques. Our picosecond sampling measurements established that the lift-off devices exhibited substantial optical response to 140 GHz. Heterodyne measurements made at 60 and 94 GHz later confirmed these findings. A novel three wave mixing technique was used to extend the heterodyne bandwidth to 130 GHz. In these experiments, millimeter waves were generated in our optically driven HEMT's and launched into waveguides. These lift off devices can be major additions to future millimeter wave integrated optoelectronic systems either as high frequency optical detectors or as optically driven tunable millimeter wave sources     

Circuit simulations combined with the electromagnetic fieldanalysis

In order to provide a means of rigorous simulation for wideband nonlinear microwave integrated circuits, the concept of a lumped device model is introduced into a three-dimensional, time-domain electromagnetic field analysis method. This makes it possible to perform both a circuit simulation including nonlinear lumped devices and an electromagnetic field analysis for distributed microwave components at the same time. As an example, the generation of picosecond pulses from a nonlinear transmission line circuit is simulated. Based on the results, the features and the validity of the method are discussed in comparison with conventional circuit simulations     

固态微波毫米波器件技术进展

固态微波毫米波半导体材料与器件、固态微波毫米波电路与模块、毫米波与太赫兹技术以及新型固态微波毫米波器件在近年来有很大的发展,在相控阵雷达、电子战、军民用通信领域有广泛的应用前景。当前这些器件应用较为集中于各类T/R组件。文章按固态微波毫米波半导体材料与器件、固态微波毫米波电路与模块、毫米波与太赫兹技术以及新型固态微波毫米波器件的顺序,概要介绍了固态微波毫米波技术的新进展。     

A new technique for the measurement of speeds of gigahertz digital IC's

We describe a new technique for the measurement of picosecond switching speeds and propagation delays in gigahertz digital IC's. This technique, based on logic-level sampling with pairs of ultrashort optical pulses at variable interpulse delays, provides accurate and reliable values of picosecond propagation delays without requiring the coupling of high-frequency electrical signals to and from the IC chip. Since this optical technique dispenses with the usual need for dicing and mounting the IC wafer in high-frequency (multigigahertz bandwidth) test fixtures, a promising application of its use is in the precise temporal characterization of multigigabit logic circuits in low-frequency (< 100-MHz) probe stations.     

分辨率约束下毫米波雷达波形参数及接收权联合设计

针对自动驾驶中有限平台空间及发射功率导致毫米波雷达目标检测性能较低的问题,该文提出一种距离及速度分辨率约束下提升毫米波雷达目标检测概率的波形参数及接收权联合设计方法。首先,基于调频连续波(FMCW)信号,所提方法建立了毫米波相控阵阵列检测模型;其次,通过分析距离及速度分辨率与发射波形参数关系,构建考虑距离及速度分辨率的发射波形参数约束;然后,基于最大化输出信杂噪比(SCNR)准则,建立具有距离及速度分辨率约束的发射波形参数及接收权值联合优化模型以改善毫米波雷达目标检测及距离速度分辨性能;最后,所提方法基于交替迭代方法求解所得复杂非线性优化问题。仿真结果表明,所提方法可自适应调整发射波形参数和接收权以提升目标检测性能同时满足距离及速度分辨率需求。     

A new multiharmonic loading method for large-signal microwave andmillimeter-wave transistor characterization

A multiharmonic loading method for nonlinear microwave and millimeter-wave transistor characterization using six-port techniques is presented. The system allows independent load tuning of an excitation signal and its harmonics. Load-pull measurements on a MESFET which have been performed at the fundamental frequency f₀ and at the second (2f₀) and third (3f₀ ) harmonics are discussed. The results highlight the importance of such measurement in designing and modeling nonlinear devices and circuits. The experimental results are found to be directly applicable for optimizing efficiency and output power in high-power MESFET amplifiers and MESFET frequency multipliers     

On the development of a multifunction millimeter-wave sensor for displacement sensing and low-velocity measurement

A new multifunction millimeter-wave sensor operating at 35.6 GHz has been developed and demonstrated for measurement of displacement and low velocity. The sensor was realized using microwave integrated circuits and monolithic microwave integrated circuits. Measured displacement results show unprecedented resolution of only 10 /spl mu/m, which is approximately equivalent to /spl lambda//sub 0//840 in terms of free-space wavelength /spl lambda//sub 0/, and maximum error of only 27 /spl mu/m. A polynomial curve-fitting method was also developed for correcting the error. Results indicate that multiple reflections dominate the displacement measurement error. The sensor was able to measure speed as low as 27.7 mm/s, corresponding to 6.6 Hz in Doppler frequency, with an estimated velocity resolution of 2.7 mm/s. A digital quadrature mixer (DQM) was configured as a phase-detecting processor, employing a quadrature sampling signal-processing technique, to overcome the nonlinear phase response problem of a conventional analog quadrature mixer. The DQM also enables low Doppler frequency to be measured with high resolution. The Doppler frequency was determined by applying linear regression on the phase sampled within only fractions of the period of the Doppler frequency. Short-term stability of the microwave signal source was also considered to predict its effect on measurement accuracy.     

皮秒脉冲泵浦光子晶体光纤超连续谱产生的研究

在包含自发拉曼散射噪声的广义非线性薛定愕方程的基础上,利用单光子噪声模型,理论研究了泵浦脉冲的中心频率和峰值功率对皮秒脉冲在光子晶体光纤中时域和频域演化的影响．发现在正常色散区泵浦,由色散和自相位调制的联合作用引起光波分裂导致皮秒脉冲展宽;零色散波长附近泵浦,光波展宽以四波混频为主;反常色散区域泵浦,调制的不稳定性将初始脉冲分解成一系列孤子脉冲后,高阶孤子分裂、拉曼散射、孤子自频是导致光谱展宽的主要机制．自相位调制感应调制不稳定性在皮秒脉冲初始分裂过程中发挥了重要作用。     

Nonlinear analysis of microwave superconductor devices usingfull-wave electromagnetic model

This paper presents a full electromagnetic wave analysis for modeling the nonlinearity in high temperature superconductor (HTS) microwave and millimeter-wave devices. The HTS nonlinear model is based on the Ginzburg-Landau theory. The electromagnetic fields associated with the currents on the superconducting structure are obtained using a three-dimensional full wave solution of Maxwell's equations. A three-dimensional finite-difference time-domain algorithm simultaneously solves the resulting equations. The entire solution is performed in time domain, which is a must for this type of nonlinearity analysis. The macroscopic parameters of the HTS, the super fluid penetration depth and the normal fluid conductivity, are calculated as functions of the applied magnetic field. The nonlinear propagation characteristics for HTS transmission line, including the effective dielectric constant and the attenuation constant, are calculated, As the power on the transmission line increases, the phase velocity decreases and the line losses increase. The nonlinearity effects on the current distributions inside the HTS, the electromagnetic field distributions, and the frequency spectrum are also analyzed     

Nonstationary nonlinear optical effects and ultrashort light pulse formation

A theory of nonstationary nonlinear wave phenomena occurring in the field of ultrashort high-intensity light pulses is developed (harmonic generation and parametric amplification stimulated Raman scattering). The main equations are given, the group velocity mismatch effects are studied, and special attention is paid to the high-conversion conditions. The possibilities of picosecond pulse narrowing on account of linear and nonlinear nonresonance parametric amplification and harmonic generation are studied in detail. The factors that determine the minimum light-pulse duration (dispersion broadening) are examined. A nonstationary theory of stimulated Raman scattering (SRS) is developed. Expressions for minimum pulse duration in forward and backward SRS are given. Reduction of Raman amplification with a picosecond pump is discussed.     

多通道高速数字收发设计

雷达系统小型化的发展趋势要求收发分系统不断提高集成度以减小设备体积。文中介绍了一种多通道高速数字收发模块的设计方法,在一个模块上同时实现16通道射频波形产生和16通道中频采集功能。波形产生基于数字直接合成方式,工作频率1.6 GHz,可直接输出射频波形,波形控制参数可通过光纤接口调节。中频采样使用多通道模数转换器芯片实现,阻抗匹配电路保证了模数转换的性能。测试表明:模块性能指标满足系统使用需求,且已成功应用于某雷达系统中。     

Propagation characteristics of picosecond electrical pulses on aperiodically loaded coplanar waveguide

A theoretical model which was developed to investigate the propagation characteristics of picosecond electrical pulses on a coplanar waveguide capacitively coupled to periodically spaced sampling channels is presented. Various factors which affect the signal waveform are analyzed in both the frequency and the time domains. The results show that in addition to modal dispersion, conductor loss, and radiation loss of the electrical signals, multiple reflections among the sampling gaps constitute another feature of the signal transfer along the waveguide. The authors have measured the picosecond pulse dispersion using the optoelectronic correlation technique. The experimental data are compared with the theoretical results     

Electronic Phase Shifter for Millimeter-Wave Semiconductor Dielectric Integrated Circuits

A new system is proposed for millimeter-wave integrated circuits. It is suggested that high-resistivity silicon be used as a medium for a dielectric waveguide. With the advent of high-resistivity silicon, propagation can occur with relatively low Ioss. Furthermore, since the medium is a semiconductor compatible with active devices, it is proposed that active devices can be constructed directly in the semiconductor dielectric guide or appendaged directly on the surface. The basic approach is similar to that used in integrated optics, except that the medium for millimeter-wave guidance is a semiconductor and the control devices rely on conductivity modulation rather than on electrooptical effects. Some particular devices suggested are oscillator, mechanical and electronic phase shifters, amplitude modulators (switches), and detectors. The first of such devices investigated has been the electronic phase shtiter. Related theory and experiments are reported here. In addition, preliminary results on oscillators imbedded in a dielectric resonator are presented.     

Measurement of on-chip waveforms and pulse propagation in digital GaAs integrated circuits by picosecond electro-optic sampling

We demonstrate precise measurement of sub-100 ps rise time on-chip electrical waveforms and of pulse propagation in digital GaAs integrated circuits with the use of picosecond electro-optic sampling. These experiments yield the first non-invasive measurement of single-gate propagation delays via direct and precise observation of on-chip waveforms at the input and output of individual logic gates internal to an integrated circuit.     

适用于毫米波集成电路的陷波空心镜象波导

本文分析了一种新的适用于毫米波集成电路的介质波导结构陷波空心镜象波导,用等效介电常数和横向表面阻抗法从理论上分析了该结构的色散特性,并讨论了各尺寸对色散特性的影响,给出了若干数值例子。     

Harmonic gain and noise in a frequency-doubling gyro-amplifier

Nonlinear gain in a 34-GHz three-stage frequency-doubling gyro-traveling wave tube (gyro-TWT) has been experimentally studied. The device consists of a thermionic electron gun, TE/sub 01//spl rarr/TE/sub 02/ fundamental gyro-TWT input section, second harmonic TE/sub 03/ intermediate buncher section, and a second harmonic TE/sub 02//spl rarr/TE/sub 04/ complex output circuit. Nonlinear bunching in the electron orbital phase generates harmonics of the input signal in the beam current, which excite the subsequent circuits at the second harmonic frequency. Since the gain is nonlinear, noise or applied sideband signals intermodulate with the carrier generating high-order products in the output. Therefore, it has been suggested that the noise figure of these devices may be unreasonably high. In this study, the complex harmonic transfer characteristics were experimentally measured and compared with calculations based on the assumption that the gyro-amplifier gain can be described, in the narrowband sense, as a classical frequency-doubling circuit. The results show that narrowband intermodulation gain is 6 dB higher than the carrier as predicted in the small signal limit, but as the device reaches saturation the nonlinear products become suppressed with respect to the carrier. Tests on the broadband gain characteristics show that output noise consists of second harmonic shot noise spontaneously excited in the output circuits along with the products of the intermodulation between external noise and the carrier. Good agreement between the experimental results and the calculations is demonstrated.