Microwave Bipolar Transistors Research Articles

Диагностика неоднородности токораспределения в гребенчатых структурах мощных биполярных и гетеробиполярных транзисторов по рекомбинационному излучению

A brief overview of methods for diagnosing current distribution and defects of high-power RF and microwave bipolar and heterobipolar transistors by recombination radiation is presented. An experimental setup is described for recording recombination radiation of structures of bipolar semiconductor devices with spatial resolution, which makes it possible to evaluate the inhomogeneity of current distribution in the comb structures of RF and microwave bipolar and heterobipolar transistors. The results of experimental testing of the installation on several samples of bipolar transistors of various types in the diode connection of the emitter junction are presented. It is established that the brightness of recombination radiation and, accordingly, the emitter current density monotonically decreases from the end to the base of the emitter tracks of current-carrying metallization, while the brightness inhomogeneity coefficient, defined as the ratio of the brightness of recombination radiation at the end to the beginning of the emitter tracks monotonically increases with increasing current flowing through the junction. An analytical model is proposed to explain the brightness distribution of recombination radiation along metallization paths in the comb structure of RF and microwave transistors.

Температурная зависимость напряжения шнурования тока в мощных ВЧ и СВЧ биполярных транзисторах

The results of studies of the temperature dependence of the voltage UKL of current lacing in power RF and microwave bipolar transistors (PBT) in the temperature range from - 60 to 90 ° C on the upgraded unit UITEP-M for measuring the thermoelectric parameters of high-power transistors are presented. The principle of operation of the installation is based on measuring the amplitude of the variable component of the voltage at the emitter junction of the PBT when a constant emitter current is passed and the sum of linearly increasing and small alternating voltage is applied to the collector; current lacing in the transistor structure manifests itself in a sharp increase in the steepness of the dependence. On a sample of PBT type KT903A, it was experimentally established that with an increase in the temperature of the housing, the current lacing voltage decreases noticeably and at a certain temperature, the TCR reaches a minimum value of UKLmin, and then increases again with an increase in the temperature of the housing. It is shown that the greater the thermal resistance of the transistor junction-housing in the diode connection, the weaker the temperature dependence of the lacing voltage. The obtained results are qualitatively explained on the basis of a one-dimensional model.

Влияние дефектов структуры и конструкции на тепловые характеристики мощных биполярных СВЧ-транзисторов

Влияние дефектов структуры и конструкции на тепловые характеристики мощных биполярных СВЧ-транзисторов

Differential method for measuring the maximum achievable transmission coefficient of active microwave quadripole

In the paper it is proposed a differential method for measuring the maximum achievable transfer coefficient of active quadripole. A new structural scheme of a measuring device and a sequence of measurements and calculations that implement the method are proposed. The differential method is intended to measure transfer coefficient of the power by an active quadripole in the microwave range at the border of its potential stability. The parameters of the active quadripole have a dimension that corresponds to the dimension of the elements of the standard W-parameters of microwave electric circuits. The results of measurements of the maximum achievable transfer coefficient of microwave bipolar transistors are presented in the paper. The advantages of the method are: 1) a small error of measurement, that is less than 5%; 2) there is no need to make individual measurements in short circuit or idling mode; 3) the small dependence of the results on the coefficient of standing wave of the loaded measuring path.

Experimental study of burnout of microwave bipolar transistors under action of a series of electric pulses

Burnout of silicon transistors under the action of a periodic train of electric pulses is experimentally studied. A numerical model and a more physically demonstrative analytical model of the pulse-to-pulse heat accumulation are in qualitative and, to a certain extent, quantitative agreement with the measured results. It is demonstrated that catastrophic failure takes place at a melting point of silicon but additional heat is needed for melting of low-temperature eutectics.

Nondestructive method for determining the voltage of current pinching in powerful radiofrequency and microwave bipolar transistors

A method and algorithm to determine the pinching voltage of current in powerful bipolar radiofrequency and microwave transistors are described, based on using the dependence of a variable component of voltage on the emitter junction of the transistor on the collector voltage without the use of the “hot spot” mode. The errors in determining the voltage of pinching are given, and the results of testing the method using serial devices are presented.

80-dB Microwave Noise from an Avalanche Transistor Circuit

Extremely high ‘excess noise ratio’ of 80 dB is observed from an avalanche transistor circuit, operating in a random pulse mode. Broadband noise spectrum measured from 30 MHz to 1 GHz exhibits good flatness with the nonuniformity of only  1 dB. Experiments have been performed with the silicon bipolar junction microwave transistors. An analog circuit model is proposed and investigated. DOI: http://dx.doi.org/10.5755/j01.eee.21.5.13324

Experimental study of the defect accumulation in the microwave bipolar transistors under the action of an electric-pulse train

It is demonstrated that a number of relatively thin electric pulses that cause the catastrophic failure of a transistor due to the accumulation of defects exponentially increases with decreasing pulse energy when the pulse energy is less than the burnout energy by a factor of no less than two. A stronger alternative destruction effect is implemented if the energy is comparable with the burnout energy.

Understanding the failure mechanisms of microwave bipolar transistors caused by electrostatic discharge

Electrostatic discharge (ESD) phenomena involve both electrical and thermal effects, and a direct electrostatic discharge to an electronic device is one of the most severe threats to component reliability. Therefore, the electrical and thermal stability of multifinger microwave bipolar transistors (BJTs) under ESD conditions has been investigated theoretically and experimentally. 100 samples have been tested for multiple pulses until a failure occurred. Meanwhile, the distributions of electric field, current density and lattice temperature have also been analyzed by use of the two-dimensional device simulation tool Medici. There is a good agreement between the simulated results and failure analysis. In the case of a thermal couple, the avalanche current distribution in the fingers is in general spatially unstable and results in the formation of current crowding effects and crystal defects. The experimental results indicate that a collector-base junction is more sensitive to ESD than an emitter-base junction based on the special device structure. When the ESD level increased to 1.3 kV, the collector-base junction has been burnt out first. The analysis has also demonstrated that ESD failures occur generally by upsetting the breakdown voltage of the dielectric or overheating of the aluminum-silicon eutectic. In addition, fatigue phenomena are observed during ESD testing, with devices that still function after repeated low-intensity ESDs but whose performances have been severely degraded.

New approach to the manufacturing of power microwave bipolar transistors: A computer simulation

A new manufacturing technology for power microwave silicon npn transistors is evaluated by 2D computer simulation in Silvaco’s SSUPREM4. It enables one to increase the effective emitter area, which makes for better power-handling and frequency capabilities, radiation hardness, and common-emitter output characteristics. Advantages of the new technology over the standard one are demonstrated.

Design of band-pass push-pull stages of power amplifiers for UHF transmitters of FM and TV broadcasting

The paper considers principles of construction, peculiarities of design, and techniques of network element calculation of push-pull amplification stages in linear bipolar microwave transistors. An example of calculation and results of experimental tests of an amplifier for transmitters of FM and TV broadcasting are presented.

Lateral Injection Utilized for Improving the Performance of Microwave Bipolar Transistors

An experimental evaluation is presented concerning the common-emitter parameters and output current–voltage characteristics of chip n–p–n transistors that are designed for pulsed conditions and have gain–bandwidth products, fT, higher than 300 MHz. The configuration of the emitter and collector junctions essentially embodies a new concept whereby injection efficiency is increased by lateral injection. It is shown that the new approach enables one to improve transistor performance. Some process techniques for the transistors are described.

A wavelet analysis of 1/ f and white noise in microwave transistors

The results of a computer-controlled experiment devoted to on-line measurements of the wavelet transform (WT) of low-frequency electronic noise voltage in bipolar microwave transistors are presented. We measure the average recurrence time of fluctuations of the WT coefficients occurring selectively in limited time and at frequency intervals. We detect two quite different behaviors in such recurrence times in the 1/ f and white noise regimes.

A dual mode wideband bipolar microwave transistor voltage-controlled oscillator design

A dual mode wideband bipolar microwave transistor voltage-controlled oscillator design

A dual mode wideband bipolar microwave transistor voltage‐controlled oscillator design

Results of the design of the microwave bipolar voltage-controlled oscillator (VCO) on coupled transmission lines, tuned by varactors in a wide frequency range, are presented. An opportunity of realization of VCO octave frequency bandwidth is shown in a common emitter bipolar transistor circuit configuration. The large-signal model for bipolar transistor is based on its small-signal Y-parameters and DC characteristics. Results of the theoretical analysis and the numerical calculations of the optimal circuit parameters and the tuning oscillator characteristics are given. ©1999 John Wiley & Sons, Inc. Int J RF and Microwave CAE 9: 424–434, 1999

Power‐gain and fmax equations based on the T equivalent circuit of high‐frequency bipolar transistors

AbstractAnalytical expressions for the maximum available power gain and fmax of a high‐frequency bipolar transistor are derived from the simple T equivalent circuit model of bipolar transistors. These equations predict the power gain of the state‐of‐the‐art microwave bipolar transistor very well and show that f/max and power gain are proportional to the transconductance and decrease as the resistance‐capacitance charging time and current gain delay time increase. © 1994 John Wiley & Sons, Inc.

Metallization of submicron microwave bipolar transistors by electroplating

Abstract Electroplating is used to make dense Au metallization patterns with dimensions smaller than 0.5 μm in microwave bipolar transistors. The structures are grown in by electron beam lithography defined patterns in PMMA resist spun on top of a Ti/TiW-N/TiW/Au plating base. Test patterns consisting of 110 nm wide lines having a height of 500 nm are readily obtained. Transistors with an emitter width as small as 0.3 μm show good performance.

Fabrication of submicron microwave bipolar transistors by direct write electron beam lithography

To study the effects of reducing the lateral dimensions of bipolar transistors to values below 1 ?m, a production process based on optical lithography, is adapted to fabricate submicron sized interdigitated microwave transistors. The emitter, base contact, and metallization patterns are defined by direct write electron beam lithography. For alignment of the patterns, special registration marks on (111) Si-wafers, compatible with further silicon processing have been developed. With a Philips EBPG/03 Beamwriter the resulting overlay accuracy is between 50 and 100 nm. The emitter and base contact resist patterns are transferred to a SiO 2 layer by reactive ion etching. The exposure dose latitude for the definition of the Ti/Pt/Au metallization pattern is severely limited by the proximity effect and a high contrast electron beam resist is needed. To tansfer by sputter etching, the resist pattern into a high quality submicron metallization pattern, Ti is used as an etch mask.

Proximity effect in high voltage electron beam lithography on Ti/Pt/Au metallization

The point exposure distribution function (PEDF) for electron beam lithography on Ti/Pt/Au has been measured for 50 keV and 100 keV electrons. The PEDF's show strong non-Gaussian behaviour. The range of the backscattered electrons does not change whereas the backscatter coefficient is significantly reduced when the electron energy is increased from 50 keV to 100 keV. The data is used in calculations of the dose distribution for a typical Ti/Pt/Au metallization pattern of a microwave bipolar transistor. The results combined with the measured contrast function, provide information over the process parameters needed for well-defined resist patterns and confirm the narrow parameter range observed in preliminary experimental work.

High-power microwave bipolar transistor modeling

This article introduces a model for high-power microwave bipolar transistors and its associated parameter-measuring strategy, whose inclusion of thermal phenomena in the dc characterization allows a good estimate of the device's thermal resistance to be obtained. This type of model provides important capabilities for solid-state radar transmitter design.