A novel technique for the analysis of dielectric height variationsin microstrip circuits

This paper presents a technique based on the full-wave, two-dimensional spectral domain method and the distributed transmission line approach to analyze structures with a combination of conductor width and dielectric height variations. The technique is applied to a regular taper and the results are compared with existing models. A matched taper transition is then designed based on simultaneous variation of the conductor width and dielectric height such that their ratio is kept constant. The analysis of such tapers is carried out and compared to measured data. It is shown that significant reduction in the return loss can be achieved with such transitions over fairly wide, tunable frequency ranges     

An analysis of wide-band transferred electron devices

The trapping conditions of a high-field domain at the anode are studied by varying doping density, applied bias voltage, and doping notch depth and width near the cathode. It is shown that the frequency band of negative conductance of the trapped-domain mode depends significantly on the doping density, and a diode having the doping density of 3 × 10¹⁵/cm³exhibits the negative conductance over the wide range from 4 GHz to 42 GHz. The upper frequency limit of the negative conductance is due to the series resistance in the low-field region and the lower limit is determined by carrier transit-time effects in high-field region. The operation mode of a trapped-domain diode will change into a traveling dipole or accumulation mode from a trapped-domain mode depending on the doping density and the operation frequency for a large-signal operation.     

Noise characteristics of GaAs and Si IMPATT diodes for 50-GHz range operation

Direct comparison of noise behaviors between GaAs Schottky-barrier junction and Si diffused p⁺-n junction diodes operating in the 50-GHz range is reported by using the same circuitry. In the oscillator operation, the GaAs diode exhibits excess "1/f^m" noise near carrier, whereas the Si diode shows flat spectrum. Far from the carrier, and AM-DSB-NSR of -133 dB in a 100-Hz bandwidth and an FM noise measure of 27.1 dB are observed for GaAs diodes. Corresponding values obtained for Si diodes are -125 and 36.2 dB, respectively. As a reflection amplifier, minimum noise figures of 27.5 and 38 dB are achieved for the GaAs and Si devices, respectively. These results indicate that the GaAs IMPATT is superior in noise behavior to the Si diode also in the 50-GHz frequency range by about 10 dB. It is emphasized that the noise induced in the bias circuit of the IMPATT oscillator is a replica of the sideband noise of the output power and can be used as an indicator to obtain a low-noise tuning condition of the oscillator.     

Very broadband bipolar VCO

A VCO tunable over a frequency range of 6.94 to 19.22 GHz in 20 V has been achieved by broadbanding a hyperabrupt varactor tuned bipolar oscillator. This was accomplished by introducing variable phase feedback in the form of a second hyperabrupt junction-varactor diode. The high operating frequency was attained by using a doubling mode circuit.     

Integrated Tunable Cavity Gunn Oscillator for 60-GHz Operation in Image Line Waveguide

The design, construction, and experimental test results of a mechanically tunable Gunn oscillator using a recessed diode metal coaxial cavity coupled to an image line waveguide is described. The oscillator frequency was changed by about 10-percent by varying the bias post length into the coaxial structure. The oscillator is designed so that both the Gunn diode and resonant cavity can be quickly replaced to provide extended frequency coverage and efficiency. This Gunn diode oscillator has provided up to 15-mW CW power at 60 GHz with 10-percent tuning range.     

Electronically tunable, 1-W CW, near-diffraction-limited monolithicflared amplifier-master oscillator power amplifier (MFA-MOPA)

An electronically tunable monolithic flared amplifier master oscillator power amplifier structure is described. This device is composed of a DBR laser tunable by free-carrier injection integrated with a flared amplifier, and generates 1-W CW of near-diffraction-limited, single mode power at λ~980 mm, while allowing wavelength tuning over a 6-Å range using a tuning current of 30 mA. This device is useful in applications requiring high power, high beam quality, and precise wavelength control simultaneously such as in frequency doubling     

Cutoff Frequency of Submillimeter Schottky-Barrier Diodes

The traditional HF model of a bulk-type (nonepitaxial) Schottky-barrier diode is extended to include the influence of skin effect, carrier inertia, and displacement current. The parasitic cutoff frequency of the extended model is calculated for n-GaAs and n-Si and compared with that predicted by the traditional model. Below the plasma frequency, the two models are found to give similar results for n-Si. For n-GaAs, however, the extended model predicts a value of cutoff frequency only one-sixth that predicted by the traditional model. With both materials, operation near the plasma frequency is impractical since it would require unrealistically small contact dimensions. Above the plasma frequency, however, both materials display a broad frequency range where operation should again be feasible. For n-Si, the extended model predicts that operation above the plasma frequency can actually be achieved with Iarger contacts than is predicted on the basis of the traditional model.     

3mm稳频脉冲雪崩管振荡器设计

介绍一种3mm波脉冲雪崩管振荡器,采用顶部斜率可调的脉冲电流给雪崩管(IMPATT Diode)供电,应用高Q腔谐振稳频,具有振荡频率高,输出功率大,频率稳定性好等优点.     

The Ridged-Waveguide-Cavity Gunn Oscillator for Wide-Band Tuning (Short Papers)

A method of construction of the Gunn oscillator for wideband frequency tuning has been developed using the ridged-waveguide cavity. The ridged waveguide can be designed to provide the dominant mode with a wide bandwidth, and also to provide the higher order cutoff modes whose resonance is a limiting factor of the tuning range for oscillators of conventional design with reduced stored energies to permit wide-band tuning. A prototype oscillator having a packaged X-band diode demonstrated an 8-18-GHz tuning range.     

Broad-Band Characteristics of EHF IMPATT Diodes

Measurements have been made of the oscillator characteristics when a GaAs EHF double-drift IMPATT diode designed for a frequency of 35 GHz is operated over an extended frequency range from 33-50 GHz. The diode which was designed for 35 GHz has a broad-band capability which allows it to produce 2.15 W at 44.1 GHz. An analytic model is shown to predict accurately the observed results. The model indicates that the upper limit in frequency can be increased by reducing the diode area or the series resistance as well as by reducing the length of the drift region.     

Microwave properties of nonlinear MIS and Schottky-barrier microstrip

It is shown that metal-insulatior-semiconductor (MIS) and Schottky-barrier microstrip structures having substrate resistivities within a certain range propagate slow waves with phase velocities that are dependent upon the instantaneous voltage at each point along the line. This and other useful properties of these microstrips can be used advantageously in a number of microwave devices. Loss measurements for the MIS microstrip structure confirm the predictred frequency dependence of the attenuation constant. While the levels of measured attenuation presently achieved are fairly high (4.5 dB/cm at 1 GHz), several methods for reducing the attenuation are proposed. A number of devices are discussed, including an electronically variable phase shifter for which attenuation and phase-shift measurements are presented.     

Functional operations of a high-resistivity n-GaAs diode by trap-controlled domain movement

Since a traveling high-field domain in a high-resistivity n-GaAs diode is composed of charges by trapped carriers, it does not easily disappear even after the external conditions to generate it are removed. By using this property of the domain, the diode is operated as a memory device.     

Some possible parametric interactions in III-V semiconductors

Some three-frequency, phase-matched, forward-wave, parametric interactions possible in III-V "ionic" semiconductors are discussed. A tunable infrared parametric oscillator, with frequency variable over a wide range with applied magnetic field, is shown to be feasible.     

A Broad-Band Second-Harmonic Mixer Covering 76-106 GHz

A broad-band second-harmonic millimeter-wave mixer has been constructed. The circuit consists of a single unencapsulated Schottky-barrier diode and embedding network which includes a wave absorber in the IF output terminal. The conversion loss of the mixer is 14.6/spl plusmn/0.9 dB over a frequency range of 76-106 GHz. The mixer is pumped by a Iocal oscillator that is tuned over the range of 37.15-52.15 GHz. The IF is kept constant at 1.7 GHz. The new mixer looks attractive for use in broad-band millimeter-wave measuring equipment, such as spectrum analyzers.     

A New MIC Doppler Module

A new microwave integrated circuit (MIC) Doppler module comprising a germanium avalanche oscillator diode and a Schottky-barrier detector diode has been fabricated and analyzed. The module is essentially a high-stability MIC oscillator, which is connected to an X-band waveguide by means of a stripline probe. In addition to high minimum detectable signal level --100 dBm, a prominent feature that has been revealed is that the Doppler signal level is practically independent of oscillator output power under a specific condition. It is also shown that a simple adaptor attached to the module can provide a direction-sensitive device in a compact form.     

1.25厘米单调谐体效应振荡器

本文报导了一种单调谐体效应振荡器.该振荡器结构类似于Kurkoawa电路.但谐振腔采用H_(011)高Q圆柱腔.该振荡器电路负载变化对振荡频率影响较小,能够避免通常反射腔稳频振荡器受到负载变化可能出现跳频的缺点.而且噪声电平比其它振荡源要小.对电路参数经过适当选择后,振荡器的输出效率能达到40～60%,输出功率30～100mW.机械牵引带宽大于600MHz.该振荡器的主腔和调谐活塞采用线胀系数不同的材料进行温度补偿.当温度循环在-40℃至+70℃的范围内,频率温度系数一般优于0.08MHz/℃,功率稳定度优于0.022dB/℃.     

YIG Resonator Circuit with Isolator Property and its Application to a Gunn Diode Oscillator

This paper presents the analysis and experiment of a newly developed YIG resonator circuit with isolator property, which is constructed with a YIG sphere, three coupling loops, and a 3-dB stripline directional coupler. This YIG circuit can be used advantageously as the toning element of a magnetically tunable oscillator. The circuit has an advantage in preventing frequency pulling and the variation of output power level of the oscillator due to a change in load condition because of the resonator circuit having isolator property at the same time. The design procedure and experiment of a magnetically tunable Gunn diode oscillator with the YIG circuit is also shown. It has been confirmed that the YIG circuit when applied to a tunable oscillator is quite useful.     

Tunable magnetostatic surface-wave oscillator

An S-band oscillator which is electronically tunable over the range 2.8?3.3 GHz is described. The oscillator makes use of a magnetostatic surface-wave delay line in the feedback loop of a solid-state amplifier.     

Analytic Model for Varactor-Tuned Waveguide Gunn Oscillators (Short Papers)

An analytic model for electronic tuning of an X-band waveguide transferred-electron oscillator is presented. The oscillator is electronically tunable by a varactor, and mechanically tunable by movement of a short circuit. The model is used to predict oscillation frequency, maximum electronic tuning range, and electronic tuning versus varactor bias voltage. Two different methods, the "zero reactance theory" and the Slater perturbation theory, are used to calculate the electronic tuning. The results of these calculations are compared to experimental results for two different oscillator configurations.