Showing papers on "IMPATT diode published in 1987"

A 90-GHz double-drift IMPATT diode made with Si MBE

Abstract: For the first time silicon double-drift IMPATT structures have been grown completely by Si molecular-beam epitaxy. The n-type layers are grown at 750 °C on low-resistivity n+-type substrates followed by p-type layers at 650 °C. The highly doped p+-layers are grown by solid-phase epitaxy in the MBE system. Device design is made for CW operation in W-band. The material is investigated by inspection of beveled samples, defect etching, TEM, SIMS, and spreading resistance measurements. Double-drift flat-profile diodes are housed and mounted employing a technological procedure approved for single-drift diodes. For initial device characterization, dc measurements are performed. Information about doping profile, series, and thermal resistances is obtained. Preliminary RF measurements delivered a maximum output power of 600 mW at 94 GHz with 6.7-percent efficiency from an unoptimized structure.

The optical control of IMPATT oscillators

Abstract: This paper describes methods of controlling the frequency of IMPATT oscillators using optical rather than electrical signals. Analytic theories of optical tuning and injection locking are presented. Results from a comprehensive large signal computer model of the optically controlled IMPATT oscillator are given, illustrating the importance of the composition of the optically generated current on the optical control performance and demonstrating the capability of optical control for rapid frequency tuning. Finally, recent experimental work on optical tuning effects in W-Band IMPATT oscillators is presented.

Semiconductor Structures for 100 GHz Silicon IMPATT Diodes

Abstract: Single Drift double drift and quasi Read double drift (QRDDR) silicon IMPATT diodes for CW operation are compared. It is shown that for high power generation efficient semiconductor structures have to be developed. A theoretical design study predicts an efficiency of 14.1 % for the QRDDR diode at 94 GHz. Experimental investigations are performed with diodes the active layers of which are grown by Si-MBE. The results confirm the predicted differences between the structures: The QRDDR diodes deliver the highest efficiency (up to 11 %) and the highest output power: 910 mW.

10 GHz space power combiner with parasitic injection locking

Abstract: An array of three microstrip patch antennas, each connected by a matching network to an impatt diode, has been investigated. Coherent radiation from the array was obtained at 10.2GHz by feeding only the centre element with an injection-locking signal, which then appeared at the input to the other two elements by free-space mutual coupling. The three impatts injection-locked successfully, producing a broadside beam with a width of 38°. An RF efficiency of 86% was measured.

MITATT mode in DDR heterostructure Impatt

Abstract: Large signal characterisation of double heterostructure DDR Impatt diode has been carried out in the millimeter-wave range considering the MITATT mode of operation. The structure of the device is p+-p2-p1-n1-n2-n+ where impact ionisation and tunneling takes place in the p1-n1 region. In this study we have considered two well-known heterostructures, e.g., InP/GaInAs/InP and InP/InGaAsP/InP and one nonconventional structure GaAs/InP/GaAs. The theoretical results of the performances of these devices as regards of output power, efficiency, and negative conductance revealed that the structures are quite promising as the source of power in the millimeter-wave range. The analysis may be used for other mm wave DDR heterostructure Impatts.

Precisely tunable impatt diode module for weather radar apparatus

Abstract: A microstrip IMPATT circuit tuning mechanism for use with RF producing IMPATT diode combinations including a microstrip circuit board and a external load line connected by a coupling spring attached to the load line and separated from the microstrip circuit by a dielectric layer, the coupling spring being manipulated by a dielectric screw inserted through the housing containing the microstrip board and further having a metallic frequency controlling screw extending through the housing and terminating before the microstrip board.

Analysis of Multiple-Step Radial-Resonator Waveguide Diode Mounts with Application to IMPATT Oscillator Circuits

Abstract: A computer-oriented method for determining the driving-point impedance of waveguide diode mounting structures incorporating stepped radial resonators is described. Results of application of the method to the study of IMPATT oscillator circuits are also given. The method is applicable to a wide range of diode mounts including the resonant-cap mount widely used in Gunn and IMPATT circuits.

Low-noise D-band IMPATT oscillators

Abstract: The single-sideband FM noise characteristics of IMPATT diode oscillators for D-band frequencies have been measured by means of a direct-detection system with a high-Q quasi-optical resonator. For an n-type silicon single-drift IMPATT diode a ?frms of 11 Hz/?Hz and a noise measure of 37 dB at 137.5 GHz and 26 mW output power was determined.

Large-signal behaviour of double-avalanche-region IMPATT diodes

Abstract: A large-signal analysis of double-avalanche-region (DAR) IMPATT diodes has been presented. Analytical expressions for the output power, admittance and efficiency of the device have been derived and their variations with different parameters studied. Results show that DAR IMPATT will be useful as a fixed-frequency millimetre-wave oscillator free from harmonics.

Planar Millimeter-Wave Circuits on Silicon Substrate

Abstract: Highly insulating silicon with a resistivity higher than 2000 Ω·cm is very promising as the base material for monolithic integrated millimeter-wave circuits. In this case in the frequency range above 40 GHz the dominant loss mechanism of planar line structures is the skin effect in the conductors [1,2] and the conductivity of the silicon substrate does not degrade the circuit performance. We already have made theoretical and experimental investigations of microstrip lines on silicon substrates. Different microstrip resonators of linear and ring geometry were fabricated on 10000 Ω·cm silicon substrates. For microstrip lines with a w/h ratio of 1. where w is the conductor width and h is the substrate height, the attenuation was found to be 0.6 dB/cm at 90 GHz. A 95 GHz microstrip oscillator with a discrete single drift region silicon impatt diode and a planar array antenna with 96 elements on an area of 8 mm × 12 mm have been fabricated on highly insulating silicon substrates [2]. In this paper we present new results on a continuously operating oscillator circuit and theoretical investigations of the disk resonator structure. In this oscillator a double drift region silicon impatt diode is used.

Novel 93 GHz injection-locked impatt oscillator

Abstract: An injection-locking technique whereby a varactor-tuned Gunn oscillator is connected directly to a high-power impatt oscillator is described. The technique does not require a circulator and results in a compact, high-power, electronically tunable source.

Pulse driven MBE GaAs IMPATT diodes for mm waves

Abstract: La conception de la diode est basee sur les dernieres recherches sur la vitesse de l'electron dans le GaAs fortement dope. Un maximum de 6,5 W comme puissance de sortie a ete atteint a 68 GHz pour des diodes plates a trajectoire unique

An Investigation of Parametric Noise in Millimeter-Wave IMPATT Oscillators

Abstract: The IMPATT oscillator used as an LO source in a receiver has often been found to contribute a large amount of excess noise to the system (sometimes more than 40 dB compared to a klystron). Often the IMPATT noise has been referred to as avalanche noise, but theoretically this should only reduce the carrier-to-noise ratio by 10-15 dB when compared to a klystron. In the following paper, we show that the excess noise far from the carrier frequency (i.e., sideband noise) is much more dependent on parametric oscillations excited below the cutoff frequency of the mount than, on avalanche noise. By modifying the Hines equation for parametric stability, we have been able to investigate the parametric noise properties of realistic millimeter-wave IMPATT oscillators. Using theoretical waveguide models, we have investigated how the sideband noise depends on various mount configurations, avalanche currents, and IMPATT diodes, The calculated curves show good correlation with the measured noise at 4 GHz from the carrier. It often has been found to be very difficult to completely reduce the parametric noise in avalanche oscillators. In these cases, the method of comparison between different mounts presented here for finding the diode-mount configuration which gives least parametric noise can be an aid in the construction of low-noise IMPATT oscillators.

Space power combiner

Abstract: An antenna array for combining in space microwave energy from a number of cillators, such as IMPATT diodes, which are controllable by injection locking. The array has elements individually driven by the oscillators, but an injection locking signal is provided in the usual manner only to the oscillator of a central element. The other oscillator are injection locked through mutual coupling between the central element and the other elements so that coherent radiation is output by the array. The radiation may be steered by phase shifters between the elements and their oscillators.

Frequency—Chirp in Solid-State mm-Wave Sources

Abstract: The frequency chirp phenomenon of IMPATT oscillators and the capability of injection synchronization in removing it are examined. Simultaneous use of injection locking and bias tuning, help in the generation of dechirped mm-wave oscillations with IMPATT diodes. Computer simulation confirms the theoretical predictions.

Computer-aided analysis of double drift region impatt diode

Abstract: The results calculated by computer for the double drift region IMPATT diode oscillator on the 8 mm waveband are reported in this paper. A comparison between single and double drift devices concerning the power output and efficiency is given. The effect of doping profile, current density and RF voltage on the performances of these devices have also been investigated. The theoretical data of these double drift IMPATT oscillator and amplifier are provided.

Low noise oscillator approaches at 140 GHz

Abstract: It was demonstrated that approaches towards oscillators with sufficient noise performance familiar up to frequencies of 100 GHz can be applied at 140 GHz with only minor modifications. Mostly due to the limitations imposed by the available InP Gunn diodes the power levels reached with second harmonic mode operation were less than at 94 GHz with GaAs devices. The two approaches employing IMPATT diodes deliver substantial output power at D-band. Which one is preferrable will be dependent on the application.

Mode Jumping and Phase Locking in Impatt Oscillators

Abstract: The effect of package parasitics on the behaviour of an IMPATT diode oscillator whether it is in a free-running or in injection-synchronized state is studied in detail. Appearance of mode jumping phenomenon in such oscillators, hitherto unknown, has been critically examined and how to get rid of this phenomenon has been predicted. Computer simulation results have been presented to corroborate the theoretical findings.

Noise in an IMPATT diode oscillator with second harmonic signals

Abstract: Multifrequency operation of IMPATT diode oscillators is important for the improvement of the oscillation efficiency of fundamental signals and for the extraction of higher-order harmonics. This paper proposes a method to analyze the noise characteristics of IMPATT diodes in multifrequency operations with higher-order harmonics, and shows the calculation results. In the analysis, a Read diode model is assumed first and the diode noise is analyzed for fundamental and second harmonic operations. Then numerical calculations are carried out to show the characteristics of the noise generated in the diode as AM and FM oscillator noise. In this numerical calculation, AM and FM noises are represented, respectively, as an N/C ratio and as a frequency fluctuation, and their variations with the amplitude and phase relation of the electric field for fundamental and second harmonic signals. Furthermore, the dependences of output power and external Q value of the oscillator on the phase of fundamental and second harmonic signals are also shown, and the optimum phase relation is described.

Near state-of-the-art power in p + -n-n + D-band IMPATT diode on a wafer with ramped n-n + interface

Abstract: Fabrication of near state-of-the-art (P 0 = 110 mW, η = 4.85 percent p+-n-n+D band (f = 124 GHz) Si IMPATT diode on a wafer with ramped n-n+interface is described. Introduction of a critical annealing step, prior to p+diffusion, in the fabrication sequence of the diode has been found to yield the above results. Possible reasons for power and efficiency enhancement has been discussed.