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Showing papers on "Junction temperature published in 1975"


Journal ArticleDOI
TL;DR: In this article, a one-dimensional model for power transistor cooling is described 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 devicesheat; 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 dc 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 TO-66 and TO-3 encased devices of mesa and planar structures were included in this study.

95 citations


Patent
30 Dec 1975
TL;DR: In this article, a current sensor provides a voltage signal which is proportional to the average current flowing through a semiconductor device junction, which is applied to a first analogue circuit which produces an output voltage indicative of the average power dissipated at the junction.
Abstract: A current sensor provides a voltage signal which is proportional to the average current flowing through a semiconductor device junction. This voltage signal is applied to a first analogue circuit which produces an output voltage indicative of the average power dissipated at the junction. The output of the first analogue circuit is applied to a second analogue circuit which outputs a voltage signal indicative of the temperature difference between the junction and a heat sink associated with the semiconductor device and to a third analogue circuit which outputs a voltage signal indicative of the temperature difference between the heat sink and ambient. The ambient temperature is sensed by an ambient temperature sensor which outputs a voltage signal indicative of the ambient temperature. A voltage summing circuit sums the output voltages from the second and third analogue circuits and from the ambient temperature sensor, and produces an output voltage indicative of the junction temperature.

37 citations


Proceedings ArticleDOI
01 Apr 1975
TL;DR: In this article, a technique is described which uses straightforward electrical measurement procedures to determine the peak junction temperature of power transistors, which can be used to generate more realistic safe operating area limits.
Abstract: A technique is described which uses straightforward electrical measurement procedures to determine the peak junction temperature of power transistors. To determine the peak temperature, standard electrical measurement techniques are altered to account for the difference between the distributions of the calibration and measurement currents in the active area of the device. For relatively uniform temperature distributions, the electrically determined peak junction temperature is only about 6% or less below the infrared measured peak temperature whereas the standard electrically measured temperature is about 10 to 25% below the infrared measured peak temperature. For severely non-uniform temperature distributions, when only about 20% of the total active area of the device is dissipating power at steady state, the electrically determined peak temperature is within 11% of the infrared measured peak temperature while the standard electrically measured temperature is more than 40% below the infrared measured peak temperature. Device operating conditions for which the junction temperature as determined by standard electrical methods, infrared techniques, and the electrical peak temperature technique equals the manufacturer's specified maximum safe operating temperature are compared with one another and with the manufacturer's specified safe operating limits. It is suggested that the electrical peak temperature technique can be used to generate more realistic safe operating area limits and to determine the validity of specified safe operating limits of power transistors.

37 citations


Journal ArticleDOI
D. R. Decker1, C. N. Dunn1
TL;DR: In this article, the temperature dependencies of the carrier ionization rates and saturated drift velocities in silicon have been extracted from microwave admittance and breakdown voltage data of avalanche diodes.
Abstract: The temperature dependencies of the carrier ionization rates and saturated drift velocities in silicon have been extracted from microwave admittance and breakdown voltage data of avalanche diodes. The avalanche voltage and broadband (2–8 GHz) microwave small-signal admittance were measured for junction temperatures in the range 280 to 590 K. An accurate model of the diode was used to calculate the admittance characteristic and voltage for each junction temperature. Subsequently, the values of ionization coefficients and saturated velocities were determined at each temperature by a numerical minimization routine to obtain the best fit between the calculated values and measured data.

28 citations


Journal ArticleDOI
H.M. Olson1
TL;DR: In this article, a simple one-dimensional computer model of the dc-thermal behavior of a Schottky-barrier GaAs IMPATT diode has been formulated to compute the conditions for thermal runaway in various designs.
Abstract: A simple one-dimensional computer model of the dc-thermal behavior of a Schottky-barrier GaAs IMPATT diode has been formulated to compute the conditions for thermal runaway in IMPATT diodes of various designs. The model has been used to determine the thermal stability conditions for three designs of GaAs IMPATT's. The computations lead to several conclusions, the most important of which are the following. a) Junction thermionic emission (leakage) current is thermally unstable, whereas avalanche multiplication is thermally stabilizing. Diode thermal stability at high junction temperature requires that the thermionic emission current be low and the avalanche multiplication be large. b) Lowering of the barrier height caused by contaminants or defects at the junction increases the likelihood of thermal runaway. c) For a given barrier height, the higher the doping of the IMPATT diode, the more resistant it will be to thermal runaway.

15 citations


Patent
14 Aug 1975
TL;DR: In this article, an improved CML (Current Mode Logic) gate having voltage and temperature compensating means for maintaining output levels and input thresholds invariant with fluctations in supply voltage and junction temperature is presented.
Abstract: An improved CML (Current Mode Logic) gate having voltage and temperature compensating means for maintaining output levels and input thresholds invariant with fluctations in supply voltage and junction temperature. The output of the compensating means, measured with respect to ground, will track variations in supply voltage on a one-to-one basis except that the output is allowed to vary by one Vbe with junction temperature. This output is supplied to the base of the constant-current source transistor which feeds the differential amplifier stage of the CML gate and to the base of a constant current source transistor whose collector is coupled to the base of the non-input transistor of the differential amplifier stage of the CML gate. The compensating circuitry includes an output transistor, resistive means for tracking variations in supply voltage, and a temperature compensation network having a temperature compensation factor of zero, both said resistive means and the output of said temperature compensation network are coupled to the base of the output transistor. The temperature compensation network achieves an overall compensation factor of zero by combining a temperature compensating subcircuit having a compensation factor of minus one with a temperature compensating subcircuit having a compensation factor of plus one via a unique voltage divider arrangement.

13 citations


Journal ArticleDOI
TL;DR: In this paper, a GaAs multimesa Read IMPATT-diode structure has been developed for operation in C band, which gives reproducible oscillator power output levels in excess of 10 W c.w. at 5 GHz.
Abstract: A GaAs multimesa Read IMPATT-diode structure has been developed for operation in C band. Such devices give reproducible oscillator power output levels in excess of 10 W c.w. at 5 GHz. Junction temperature rises less than1 80 deg C are observed during high-power operation. The diodes are constructed with an integral gold-plated heatsink and bonded with Au : Sn eutectic solder in a small package.

11 citations


Patent
03 Oct 1975
TL;DR: In this paper, a temperature compensation system using forward biased pn semiconductor junctions as temperature sensing elements to compensate for the rate of heat loss or gain by controlling the temperature of a fluid heat exchange medium.
Abstract: A temperature compensation system using forward biased pn semiconductor junctions as temperature sensing elements to compensate for the rate of heat loss or gain by controlling the temperature of a fluid heat exchange medium. A differential amplifier is driven by changes in the junction voltage drops and controls power to the heating element so as to maintain a controlled relation between the temperature being overcome and the temperature of the heat exchange medium.

8 citations


Journal ArticleDOI
TL;DR: In this paper, a GaAs IMPATT device using p+n and p-n junctions with hi-lo and lo-hi-lo structures with a maximum efficiency of 26.8% and a maximum peak power of 12.8 W with 25% efficiency have been observed in the X band.
Abstract: GaAs IMPATT devices using p+–n and p–n junctions with hi–lo and lo–hi–lo structures were investigated. A maximum efficiency of 26.8% and a maximum peak power of 12.8 W with 25% efficiency have been observed in the X band. A median life of 107 h is predicted for a 237°C junction temperature.

6 citations


Journal ArticleDOI
TL;DR: In this article, an improved current rating system for high-current high-frequency thyristors is described, which incorporates a combination of simultaneously measured highfrequency parameter data with a computer program based on thyristor models.
Abstract: The composition and use of an improved current rating system for high-current high-frequency thyristors is described. Commonly accepted methods for rating thyristors at low-frequency wide-pulsewidth conditions were not adequate for this task. To fill this void, a new system was developed that incorporates a combination of simultaneously measured high-frequency parameter data with a computer program based on thyristor models using device parameters measured at low frequency. A complete description of the high-frequency simultaneous parameter data is given, including the direct measurement of peak junction temperature, turnoff time, which is used as an indirect check on the junction temperature measurement, and dissipated power. A description of the computer models, including those for instantaneous active area, charge modulation, and thermal impedance as a function of area, is also given. These models generally require the input of empirical parameters, the value of which can be measured at low repetition rate. These include the steady state and dynamic forward drop for the charge modulation model, the plasma spreading velocity for the instantaneous active area model, and the steady state dc thermal resistance for the thermal impedance model. A direct comparison between computer predictions and actual performance for a particular device is presented as a check on rating system performance. When the computer correctly predicts device performance for specific cases, it can be used to derive ratings for any arbitrary current waveform.

6 citations


Journal ArticleDOI
TL;DR: In this article, beam-leaded plated heat sink (BLPHS) C- and X-band GaAs IMPATT diodes were developed for use as high-power microwave oscillators.
Abstract: GaAs IMPATT devices are currently being developed for use as high-power microwave oscillators. Since low thermal impedance is required for dissipation of high input powers, this device is usually fabricated by thermal compression bonding to a diamond heat sink or a multimesa plated heat sink. This paper discusses the development of 4-mesa beam-leaded plated heat sink (BLPHS) C- and X-band GaAs IMPATT diodes. A description of the fabrication procedures is given, whereby the beam-lead interconnects are formed as part of the wafer fabrication procedure. Diodes tested at 5 GHz give up to 7.3 W of output power at 13.5- percent efficiency at a junction temperature of approximately 210°C. X-band diodes, although the data is more limited, show efficiencies up to 16.5 percent (2.2 W) for fiat profile diodes, and up to 20.8 percent for lo-hi-lo profile diodes. BLPHS diodes, therefore, are limited in their efficiency by the epitaxial material's doping profile. Accelerated stress aging data taken to date on BLPHS units show them to have an estimated mean time to failure greater than 2 × 106h at 200°C, which is comparable to thermal compression bonded to diamond units.

Journal ArticleDOI
TL;DR: In this article, a diode model was constructed which simulates second breakdown and which allows for the calculation of junction temperature as a function of time in the reverse region, which is useful for predicting second breakdown for general inputs, and in general circuit configurations.
Abstract: A diode model has been constructed which simulates second breakdown and which allows for the calculation of junction temperature as a function of time in the reverse region. The model was generated for the NET-2 circuit analysis code, and also includes avalanche breakdown. Second breakdown is assumed to begin at the critical temperature at which the resistivity is a maximum; at this point the junction area is caused to rapidly decrease, causing an increase in the temperature and the thermally generated leakage current. This results in the rapid voltage drop characteristic of second breakdown. With the addition of temperature calculations in the forward region and capacitive effects, it is anticipated that the model will be useful for predicting second breakdown for general inputs, and in general circuit configurations.

Journal ArticleDOI
TL;DR: In this paper, the carrier temperature effects arising in a p−n junction are discussed by solving a chosen set of conservation equations, and an analytic solution is found for the current flow assuming small departures of the temperature from equilibrium.
Abstract: Carrier temperature effects arising in a p−n junction are discussed by solving a chosen set of conservation equations. An analytic solution is found for the current flow assuming small departures of the carrier temperature from equilibrium, and a numerical solution involving large carrier temperature variations is presented. The reverse bias at which avalanche breakdown is predicted for a germanium diode is in agreement with experiment.

Proceedings ArticleDOI
01 Oct 1975
TL;DR: In this article, the diode area for optimum oscillator power is a function of junction temperature rise and thus diodes for reliable oscillators will have different design criteria from devices giving the more spectacular results.
Abstract: By considering the loss of a practical millimetre-wave oscillator circuit, the variation of oscillator power with diode area for a constant junction temperature rise is examined, the results being scaled from measurements on a known device. It is concluded that the diode area for optimum oscillator power is a function of junction temperature rise and thus diodes for reliable oscillators will have different design criteria from devices giving the more spectacular results. Results are presented for silicon single and double-drift and gallium arsenide single drift IMPATT diodes over the 30-60 GHz range.