Millimeter wave monolithic high electron mobility (HEM) varactor diode-grid frequency tripler arrays

High Electron Mobility (HEM) varactor structures have been studied for millimeter-wave monolithic diode-grid frequency tripler array applications. The improved HEM varactor diode structures provide a highly nonlinear C-V characteristic (i.e., a steep slope of the C-V curve and a large capacitance ratio) which produces high harmonic generation efficiency and reduce the power requirement for efficiently pumping each device. The effects of the light illumination on the C-V characteristics of the Barrier-Intrinsic-N⁺ (BIN) varactor diode have also been studied and the results will be discussed in this paper. In the development of a monolithic diode-grid frequency multiplier array, the low-loss quasioptical configuration is used for the construction of the multiplier circuit. The study of the effects of the light illumination on the C-V characteristics of varactor diode is important in understanding the potential applications of the quasi-optical varactor diode-grid frequency multiplier array circuit.     

Design consideration of monolithic millimeter-wave barrier varactor diode frequency multiplier arrays

A new device structure for highly efficient frequency tripling in the millimeter and submillimeter wavelength regions is presented. The Barrier-Intrinsic-N⁺ (BIN) diode structure [1,2] is modified for highly efficient millimeter- and submillimeter-wave frequency tripling device to be employed into the monolithic back-to-back diode frequency tripler array. The modified BIN diode structures have series resistances of a few ohms and cut-off frequencies in the terahertz range. The modified BIN diode structures have weaker C-V nonlinearities than the BIN diode structure does, however, the modified BIN structures have much higher intrinsic cut-off frequencies than does the BIN counterpart. The C-V nonlinearity, capacitance ratio, breakdown voltage, series resistance and cut-off frequency of this new device structure will be discussed in this paper. In addition, the calculated high-frequency performance of this device using a large-signal nonlinear circuit model will be presented in this paper. The operation and performance of the monolithic diode-grid frequency tripler arrays employing large numbers of the modified BIN diodes will also be discussed in this paper.     

Quasi-optical planar arrays with FETs and slots

This work describes the design concept and experimental results for prototypes of two-dimensional quasi-optical power-combining arrays. Several different quasi-optical circuits were used to obtain the fundamental data for this study. How to incorporate the antenna input impedance into the active antenna circuit and how to analyze the strong coupling condition with two operating modes are addressed using large-signal analysis. Several circuit configurations are demonstrated, including a single active antenna operating at 9.3 and 24.0 GHz, a six-element linear power-combining array operating at 15.6 GHz, and four-element and sixteen-element two-dimensional power combining arrays operating at 10.4 and 7.8 GHz. Important characteristics such as antenna patterns and tuning ranges are discussed. The prospects for a two-dimensional monolithic quasi-optical power-combining array are discussed     

Control techniques for millimeter-wave active arrays

Control techniques for millimeter-wave active arrays are considered. In addition to voltage control, optical and quasi-optical approaches are discussed as analog control techniques. Digital control techniques discussed include on/off switching arrays and designs with superimposed device and/or grid structures for multi-bit capability. A quasi-optical Q switch, capable of high peak power pulse generation, is discussed as an example application of these techniques.     

0．22THz准光波导回旋返波管的设计与模拟研究

回旋返波管作为一种频率可调谐的大功率太赫兹辐射源器件,具有较好的实用前景。本文根据回旋返波管线性理论设计了一只中心工作频率在0．22THz的准光波导回旋返波管,采用自主研发的三维粒子模拟软件CHIPIC对其进行数值模拟研究,分析其工作特性。仿真结果表明：所设计的回旋返波管可获得14kW的峰值功率输出,输出功率大于5kW时调谐带宽大于1GHz。     

MMIC毫米波倍频器的研究

在介绍倍频器工作原理、各种实现方法及其优缺点的基础上,阐明了采用MMIC(单片微波集成电路)工艺实现高性能、高可靠性、小型化毫米波倍频器芯片的技术特点及应用需求,比较了单管和平衡两种不同结构MMIC毫米波倍频器的优点与不足,全面综述了国内外对MMIC毫米波倍频器的研究情况,介绍了MMIC毫米波倍频器的最新研究进展,展望了MMIC毫米波倍频器的发展趋势,提出了一些建议。     

A quasioptical doubler-array

The design of a planar quasioptical doubler configuration with an output frequency of 290 GHz is presented. Frequency conversion is realized with a monolithic Schottky — varactor array. Coupling of electromagnetic energy from beam waveguide to chip and vice versa is carried out with integrated antenna arrays. Electromagnetic field calculations describe coupling effects between the single array elements. RF—measurements of multiplier performance are also presented.     

Quasi-optical VCOs

Quasi-optical grid voltage controlled oscillators (VCOs) are presented. These VCOs are the first demonstration of a quasi-optical system consisting of several periodic arrays loaded with solid-state devices. A quasi-optical VCO consists of an array of oscillators, a variable capacitance array, and a mirror. The mirror provides feedback for locked power-combining of a large number of MESFET oscillators that load a two-dimensional metal grid on a dielectric substrate. The frequency can be electrically tuned either with gate bias or with another array loaded with varactor diodes. When the varactor bias voltage is changed, the capacitance of the diodes changes, which in turn modulates the frequency of the output power-combined wave. Two types of arrays are presented, one consisting of short dipoles, and the other of bow-tie elements. As expected, the bow-tie VCO has better performance than the dipole VCO, due to its broadband impedance. A 10% tuning bandwidth with less than 2 dB power change was measured in the case of a bow-tie VCO     

Experimental 6-GHz frozen wave generator with fiber-optic feed

Experimental results from an optically activated 6 GHz frozen wave generator (FWG) test device are presented. The several system components needed to produce a low-cost monolithic pulsed power source suitable for large phased arrays are demonstrated. Static electric energy stored in 50 ohm microstrip transmission lines is released by fast GaAs photoconductive (PC) switches activated by 50 picosecond laser pulses distributed over fiber-optics. The present device is of hybrid construction, using commercial fiber-optic pigtailed integrated optic couplers and semi-insulating (SI) GaAs metal-semiconductor-metal (MSM) photoconductive switch chips bonded into microstrip. However, exclusive of the laser, the design lends itself to monolithic microwave and integrated optic techniques especially at high frequencies. Experimental test results compare well with circuit simulation predictions, showing that hybrid techniques introduce negligible parasitics at the design frequency. Lower resistance PC switches are needed to fully demonstrate the high power performance capabilities of this type of device     

Millimeter-wave diode-grid frequency doubler

Monolithic diode grid were fabricated on 2-cm² gallium-arsenide wafers in a proof-of-principle test of a quasi-optical varactor millimeter-wave frequency multiplier array concept. An equivalent circuit model based on a transmission-line analysis of plane wave illumination was applied to predict the array performance. The doubler experiments were performed under far-field illumination conditions. A second-harmonic conversion efficiency of 9.5% and output powers of 0.5 W were achieved at 66 GHz when the diode grid was pumped with a pulsed source at 33 GHz. This grid had 760 Schottky-barrier varactor diodes. The average series resistance was 27 Ω, the minimum capacitance was 18 fF at a reverse breakdown voltage of -3 V. The measurements indicate that the diode grid is a feasible device for generating watt-level powers at millimeter frequencies and that substantial improvement is possible by improving the diode breakdown voltage     

Single-ended HEMT multiplier design using reflector networks

Microwave and RF frequency multipliers are employed in a large number of communications, radar, civilian, and military systems. This paper presents the development of active doublers operating in S and C frequency bands. These devices are unique in that high electron-mobility transistors (Fujitsu FHX35LG) are employed in an unbalanced configuration utilizing “reflector” networks simultaneously on the input and output to reflect the second harmonic signal into the gate of the device and the fundamental signal into the drain simultaneously at appropriate phase angles to optimize performance. Measured and simulated results are presented on over 20 multiplier designs to verify the design philosophy. Conversion gains of approximately 7 dB are presented for narrow-band designs (5% bandwidth), 5 dB for medium-bandwidth designs (15%), and 4 dB for wide-bandwidth designs (35%). The fundamental and third harmonic rejection is approximately 40 dBc for the narrow-band designs and greater than 50 dBc for the medium and wide-band designs     

Fully Monolithic Cellular Buck Converter Design for 3-D Power Delivery

A fully monolithic interleaved buck dc-dc point-of-load (PoL) converter has been designed and fabricated in a 0.18-mm SiGe BiCMOS process. Target application of the design is 3-D power delivery for future microprocessors, in which the PoL converter will be vertically integrated with the processor using wafer-level 3-D interconnect technologies. Advantages of 3-D power delivery over conventional discrete voltage regulator modules (VRMs) are discussed. The prototype design, using two interleaved buck converter cells each operating at 200 MHz switching frequency and delivering 500 mA output current, is discussed with a focus on the converter power stage and control loop to highlight the tradeoffs unique to such high-frequency, monolithic designs. Measured steady-state and dynamic responses of the fabricated prototype are presented to demonstrate the ability of such monolithic converters to meet the power delivery requirements of future processors.      

New concedpts for high frequency and high power frequency multipliers and their impact on quasi-optical monolithic array design

Varactors have been extensively employed for harmonic generation, where high cut-off frequency is dependent upon small C _min , which is typically achieved using small device active area. However, small area limits the output power. Furthermore, the power and frequency dependences of the series resistance in the epitaxial region degrade the efficiency and cut-off frequency as well. As a result, currently utilized varactors are only officient for relatively low power generation and limited output frequency. Herein, we describe our new approach where by epitaxially stacking single quantum barrier structures, more than an order of magnitude improvement in cut-off frequency and power handling ability may be possible. Alternatively, by combining a Schottky barrier with stacked single quantum barriers, superior performance can also be achieved. These concepts can be readily employed for quasi-optical frequency multiplier arrays, and appear to result in simplified fabrication compared to other devices. The design of high performance quasi optical arrays requires optimization of the passive (metalization) grid as well as the embedded semiconductor devices. Recent work has resulted in an improved impedance model for the standard diode-loaded strip array, including a quantitative estimate of the shunt capacitance introduced across the diode by the discontinuity of the metal strip at the diode site (“gap”). The value of this capacitance exceeds the predictedC _min for these new devices. We discuss two grid design approaches that can suppress this capacitance.     

High-Power Pulsed UHF and L Band p+-n-n+ Silicon TRAPATT Diode Lasers

The design and performance of both the lumped-element TRAPATT oscillator circuit and deep-diffused p+-n-n+ silicon TRAPATT diodes designed primarily for pulsed RADAR applications in the UHF and L band frequency ranges are discussed. Circuit conditions for optimum performance are described. Methods of optimizing diodes are presented. Diode performance capability is shown to depend on the relative position of the junction in the device depletion region. Peak powers close to 900 W and maximum conversion efficiencies of 40 percent have been achieved from diodes with large p-region width to total depletion region width ratios. RF leading-edge jitter of less than 1 ns has been obtained under optimum circuit and diode operating conditions.     

Integrated Circuit Compatible Surface Acoustic Wave Devices On Gallium Arsenide

Improvements in gallium arsenide materials technology have led to the rapid development of GaAs MIC, CCD, and digital IC technologies in the last several years. In this paper we consider the additional capabilities afforded by the inherent piezoelectric properties of GaAs. The primary emphasis of the work is on surface acoustic wave (SAW) device configurations using MESFET and Schottky-barrier diode fabrication techniques which are compatible with the eventual monolithic integration of electronic devices on the same substrate. The GaAs SAW technology described here provides a means for achieving electronically variable delay, high-Q resonator structures for VHF/UHF oscillator frequency control, and real-time signal processing operations such as convolution and correlation. Prototype device designs and performance are described, includlng two-port GaAs SAW resonators with Q's as large as 13 000 at 118 MHz and a programmable GaAs SAW PSK correlator capable of signal correlation at 10-MHz chip rates. Further GaAs SAW device development required for increasing the operating frequency range to 500 MHz and processing bandwidth to 100 MHz is indicated.     

On the performance analysis and design of an integrated front-end PIN/HBT photoreceiver

A detailed study on the performance analysis and optimum design of an integrated front-end PIN/HBT photoreceiver for fiber-optic communication is presented. Receiver circuits with two different transimpedance amplifiers-a single-stage common emitter (CE) amplifier and a three-stage amplifier comprising a CE amplifier and two emitter followers (EFs), are analyzed assuming a standard load of 50 /spl Omega/. A technique to include the transit-time effect of a PIN photodetector on the overall receiver circuit analysis is introduced and discussed. Gain-bandwidth product (GB) and gain-bandwidth-sensitivity measure product (GBS) are obtained as functions of feedback resistance (R/sub F/) and various device parameters. Hence, some optimum designs are suggested using a photodetector of area 100 /spl mu/m/sup 2/ and with a feedback resistance of 500 /spl Omega/. The bandwidth plays a major role in determining the optimum designs for maximum GB and maximum GBS. A bandwidth >8 GHz has been obtained for the photoreceiver even with a single-stage CE amplifier. The optimum design for a receiver with a three-stage amplifier shows a bandwidth of 35 GHz which is suitable for receivers operating well beyond 40 Gb/s; however, in this case, the gain is reduced. The performance of different fixed square-emitter structures are investigated to choose the optimum designs corresponding to different gains. Very low power dissipation has been estimated for the optimized devices. The noise performance of the devices with optimum designs was calculated in terms of the minimum detectable optical power for a fixed bit-error rate of 10/sup -9/. The present design indicates that GB and noise performance can be improved by using an optimum device design.     

Phase-locked millimeter-wave two-port second-harmonic Gunnoscillators

Two-port harmonic oscillators have been developed which are suitable for voltage-controlled-oscillator (VCO) operation in frequency stabilized systems. Two oscillator designs are presented. The first has a fundamental frequency cavity located above the harmonic output cavity and the fundamental is coupled by means of the Gunn device bias-line filter. The second design is an in-line structure which uses a waveguide taper as the filter element separating the fundamental and harmonic frequency components. The latter design is a translation of the first oscillator concept onto a single plane, so that the prospect of an integrated monolithic version is conceivable. The performance of the oscillators is discussed, and a demonstration of their use in a heterodyne phase-locked loop control system is presented     

Monolithically integrated HgCdTe focal plane arrays

The cost and performance of hybrid HgCdTe infrared (IR) focal plane arrays are constrained by the necessity of fabricating the detector arrays on a CdZnTe substrate. These substrates are expensive, fragile, available only in small rectangular formats, and are not a good thermal expansion match to the silicon readout integrated circuit. We discuss in this paper an IR sensor technology based on monolithically integrated IR focal plane arrays that could replace the conventional hybrid focal plane array technology. We have investigated the critical issues related to the growth of HgCdTe on Si read-out integrated circuits and the fabrication of monolithic focal plane arrays: (1) the design of Si read-out integrated circuits and focal plane array layouts; (2) the low-temperature cleaning of Si(001) wafers; (3) the growth of CdTe and HgCdTe layers on read-out integrated circuits; (4) diode creation, delineation, electrical, and interconnection; and (4) demonstration of high yield photovoltaic operation without limitation from earlier preprocessing such as substrate cleaning, molecular beam epitaxy (MBE) growth, and device fabrication. Crystallographic, optical, and electrical properties of the grown layers will be presented. Electrical properties for diodes fabricated on misoriented Si and readout integrated circuit (ROIC) substrates will be discussed. The fabrication of arrays with demonstrated I–V properties show that monolithic integration of HgCdTe-based IR focal plane arrays on Si read-out integrated circuits is feasible and could be implemented in the third generation of IR systems.     

Design of High-Performance Millimeter Wave and Sub-Millimeter Wave Quasi-Optical Isolators and Circulators

Faraday rotators using permanently magnetized ferrite materials are used to make quasi-optical isolators and circulators at millimeter wave and sub-millimeter wave frequencies that have far higher performance than their waveguide equivalents. This paper demonstrates state-of-the-art performance for four-port quasi-optical circulators with 60-dB isolation, 0.2-dB insertion loss, and better than 80-dB return loss for devices centered at 94 GHz. A method is presented for the accurate characterization of the complex permeability and permittivity of permanently magnetized ferrites via a series of frequency and polarization dependent transmission and reflection measurements. The dielectric and magnetic parameters for the sample are determined by fitting theoretical curves to the measured data. These fitted parameters are then used in a model for a complete quasi-optical Faraday rotator, including matching layers, allowing the accurate design and fabrication of these devices for any specific operational frequency band in the millimeter wave and sub-millimeter wave regime. Examples are given showing typical results and demonstrating how temperature cycling can significantly improve the temperature stability of these devices, while allowing fine tuning of the center frequency. We also indicate the performance possible at higher frequencies to above 1 THz and outline performance of truly planar isolators where lossy polarizer material is built into the Faraday rotator matching structure