Showing papers on "Junction temperature published in 1974"
10 Jun 1974
TL;DR: In this paper, the difference between the measured thermal impedance of power transistors when determined by the pulsed heating curve and cooling curve techniques is discussed, and the theoretical predictions of the model are shown to be in good agreement for practical applications with three-dimensional computer simulations and experimental results.
Abstract: Differences between the measured thermal impedance of power transistors when determined by the pulsed heating curve and cooling curve techniques are discussed. These differences are shown to result primarily because the power density distributions of these devices change as the devices heat; as a result of these changes the heating curve and the cooling curve are not conjugate. It is shown that the cooling curve technique, when the cooling curve is initiated from the most non-uniform steady state thermal distribution, (maximum voltage, maximum power) will indicate a larger value for the thermal impedance than will the pulsed heating curve technique, even for pulses in excess of the d-c power level. A one dimensional model for power transistor cooling is described. The theoretical predictions of the model are shown to be in good agreement for practical applications with three-dimensional computer simulations and experimental results. Using this model, it is possible to estimate an average junction temperature and the area of power generation at steady state. Both T0-66 and TO-3 encased devices of mesa and planar structures were included in this study.
36 citations
Patent•
02 Dec 1974TL;DR: In this article, a circuit for monitoring semiconductor junction temperature includes means for obtaining a signal representing the current flowing through the semiconductor, a current controller, an electrical analog of the thermal system, a direct current supply, and a voltage level detector.
Abstract: A circuit for monitoring semiconductor junction temperature includes means for obtaining a signal representing the current flowing through the semiconductor, a current controller, an electrical analog of the thermal system of the semiconductor, a direct current supply, and a voltage level detector. The current controller is connected in circuit with the analog and the combination to the d.c. supply. The current conducted by the controller via the analog is controlled by the signal such that the voltage across the analog indicates junction temperature and this voltage is monitored by means of the level detector.
15 citations
TL;DR: In this paper, both epitaxially grown GaAs p+n junction and Cr Schottky barrier diodes have been fabricated, and power, efficiency, and noise performance of the devices are reported.
Abstract: A recently developed procedure, incorporating both preferential electrochemical etching for wafer thinning and electroplating for heat sink formation has been applied to the fabrication of K a band (26.5-40 GHz) GaAs IMPATT's. Both epitaxially grown GaAs p+n junction and Cr Schottky barrier diodes have been fabricated. This procedure makes possible the batch fabrication of small area diodes ( cm2) over a large wafer area. The diodes have been operated both in the oscillator and stable-amplifier mode. Power, efficiency, and noise performance of the devices is reported. The p+n diodes, which could withstand junction temperature of over 300°C, gave the best power and efficiency. Powers as high as 680 mW with 12.4 percent efficiency at 34.8 GHz and an efficiency as high as 16 percent with 390 mW at 29.5 GHz have been achieved. The Cr Schottky diodes were unable to withstand junction temperatures in excess of 200°C and therefore produced less power despite the potentially better power handling capability. The highest power obtained from a Cr Schottky is 470 mW with 12.5 percent efficiency at 34 GHz. Comparable oscillator noise performance has been obtained with both types of diode. The best AM (DSB) double sideband NSR obtained is -135 dB in a 100 Hz window at 1.5 MHz from the carrier. An rms frequency deviation as low as 13 Hz in a 100 Hz window has been observed with a power output of 164 mW at 35.4 GHz by raising the external Q to 138. A lowest FM noise measure of 23 dB was achieved by reducing output power to 16 mW. The amplifier noise figure measured for both p+n and Cr Schottky diodes is 26 dB.
10 citations
TL;DR: In this paper, a broadband small-signal characterization of an IMPATT diode mounted in a package is presented, where the diode series resistance and junction admittance above breakdown are evaluated.
Abstract: A method is described that permits a broad-band small-signal characterization of an IMPATT diode mounted in a package. From automatic-network-analyzer measurements on a package-shaped metal dummy, an empty package, and the diode under test biased below and above breakdown, the method allows first determination of a coupling-circuit parameter, bonding-wire inductance, and diode series resistance, and then evaluation of junction admittance above breakdown. Experimental results on silicon (Si) p+-n-n+ diodes over 2.5-15 GHz are shown. Nearly frequency-independent bonding-wire inductance is observed. Avalanche frequency squared (f/sub a//sup 2/) is found to be sublinear with respect to dc current density (I/sub d), possibly due to a variation of junction temperature (T/sub i/). An experimental formIda for (f/sub a//sup 2/) / (I/sub d) is obtained in terms of (T/sub i/).Detailed comparisons of the measured junction admittance with an existing analytical theory indicate a good agreement, if a suitable amount of saturation current is postulated, and also suggest that the estimated amount is in excess of the prebreakdown saturation current.
10 citations
TL;DR: In this paper, analytical and experimental investigations of the transient thermal behavior of Trapatt diodes are presented, where junction temperature calculations are made as a function of diode geometry, heat sink materials, dissipated power level and pulsewidths up to 50 µs.
Abstract: Analytical and experimental investigations of the transient thermal behavior of Trapatt diodes are presented. Although oriented to Trapatt diodes, the techniques described are equally applicable to numerous other solid state devices operated in a pulsed mode. Junction temperature calculations are made as a function of diode geometry, heat sink materials, dissipated power level, and pulsewidths up to 50 µs. Experimental measurements using infrared and voltage breakdown techniques are described. Guidelines for transient junction temperature minimization are given.
4 citations
01 Apr 1974
TL;DR: In this article, the output powers of 80 GHz band abrupt-junction IMPATT diodes were found to be limited not only by thermal restriction, but also by electronic restriction.
Abstract: Output powers of 80-GHz band abrupt-junction IMPATT diodes are found to be limited not only by thermal restriction, but also by electronic restriction. Equations giving optimum junction diameters at different junction temperature rises are derived analytically, considering these two factors. When compared with the experimental results, they are verified to be useful for the optimum design of millimeter-wave IMPATT diodes.
3 citations
10 Jun 1974
TL;DR: The capacity of a solid-state device, as ordinarily rated, varies widely depending on the current waveform, duty cycle, case temperature, etc. The underlying junction temperature limits should, however, be invariant.
Abstract: The current capacity of a solid-state device, as ordinarily rated, varies widely depending on the current waveform, duty cycle, case temperature, etc. The underlying junction temperature limits should, however, be invariant.
3 citations
01 Apr 1974
TL;DR: In this article, a life-test study was made of a microwave power transistor-employing aluminum metallization, where the life tests were conducted under dc overstress conditions to accelerate the rate of failure as a result of electro-migration.
Abstract: A life-test study was made of a microwave power transistor-employing aluminum metallization. The life tests were conducted under dc overstress conditions to accelerate the rate of failure as a result of electro-migration of the metallization system. Extrapolation of the data obtained showed a predicted MTF of approximately one hundred years for the device under test at a typical operating-current density of 8.4 × 104 A/cm2 and junction temperature of 150°C. Analysis of the failures revealed the presence of both aluminum and silicon electromigration, with the latter the primary cause of failure, A failure-rate model was constructed from the data relating MTF to activation energy, temperature, and current density.
2 citations
TL;DR: In this paper, a fair model for junction temperature rise estimations is proposed, in the knowledge of switchover power vs time function and constructional data of a transistor, both as a function of time and the depth of thermal penetration on both collector junction sides.
2 citations
01 Apr 1974
TL;DR: In this paper, fixed junction temperature operating tests have been conducted on two types of Ka-band IMPATT diodes: commercially available silicon devices, and gallium arsenide devices fabricated in-house.
Abstract: Fixed junction temperature operating tests have been conducted on two types of Ka-band IMPATT diodes: commercially available silicon devices, and gallium arsenide devices fabricated in-house. Median operational life of 106 hours at a junction temperature of 200°C has been predicted for the silicon devices, and the dominant failure mechanism has been identified as a localized penetration weakness of the platinum barrier layer. Experiments on the metallization layers of the GaAs devices have produced diodes with lower operating temperatures for a given added power, and longer life at the only operating temperature where the two devices have been compared, 350°C.
2 citations
12 Jun 1974
TL;DR: In this article, K/sub a/-band GaAs p-n junction IMPATT diodes have been fabricated which have delivered 450 mW of added power with 9.6% efficiency at a junction temperature of 275/spl deg/C.
Abstract: K/sub a/-band GaAs p-n junction IMPATT diodes have been fabricated which have delivered 450 mW of added power with 9.6% efficiency at a junction temperature of 275/spl deg/C. Results of life tests predict operating life in excess of five years at this temperature,
01 Jan 1974
TL;DR: In this paper, the authors measured junction admittance with an existing analytical theory, and also suggest that the estimated amount is in excess of the pre-breakdown saturation current, if a suitable amount of saturation current is postulated.
Abstract: package-shaped metal dummy, an empty package, and the diode under test biased below and above breakdown, the method allows lirst determination of a coupling-circuit parameter, bonding-wire inductance, and diode series resistance, and then evaluation of junction admittance above breakdown. Experimental results on silicon (SI) p+-n-n+ diodes over 2.5–15 GHz are shown. Nearly frequency-independent bonding-wire inductance is observed. Avalanche frequency squared (~.z) is found to be sublinear with respect to dc current density (Id), possibly due to a variation of junction temperature (!!’i). An experimental formIda forja2/~d is obtained in terms of 2“~.Detailed comparisons of the measured junction admittance with an existing analytical theory indicate a good agreement, if a suitable amount of saturation current is postulated, and also suggest’that the estimated amount is in excess of theprebreakdown saturation current.