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Showing papers on "Junction temperature published in 1970"


Journal ArticleDOI
TL;DR: In this paper, the authors calculated the noise resistance of the field effect transistor taking into account high-field effects such as mobility saturation and hot carrier temperature upon the thermal noise, and compared it with measurements of the noise of a junction gate FET and a MOS tetrode with short active channels.
Abstract: The noise resistance of the field-effect transistor has been calculated taking into account high-field effects such as mobility saturation and hot carrier temperature upon the thermal noise. The result of the calculations can be represented by a practical formula. The calculated results have been compared with measurements of the noise of a junction gate FET and a MOS tetrode with short active channels. The agreement is reasonable. At room temperature the effect is moderate, but at low temperatures it is considerable.

42 citations


Patent
23 Jun 1970
TL;DR: In this paper, a circuit for monitoring the junction temperature of a conducting thyristor by measuring the temperature of the reference point and synthesizing the thermal response of the physical configuration between the junction and that reference point is presented.
Abstract: A circuit for monitoring the junction temperature of a conducting thyristor by measuring the temperature of a reference point and synthesizing the thermal response of the physical configuration between the thyristor junction and that reference point. The synthesized signal generated is indicative of the temperature difference between the junction and said reference point. That signal is combined with a signal indicative of the measured reference temperature to provide an output signal indicative of junction temperature per se. The output signal may be utilized to stop conduction in the thyristor when the monitored temperature exceeds a predetermined level.

32 citations


Journal ArticleDOI
S. Ikeda1, S. Tsuda1, Y. Waki1
TL;DR: In this paper, the maximum allowable junction temperature based on time-to-failure was estimated for the nonrepetitive and repetitive current pulse ratings of a thyristor with a combination of analytical and experimental methods.
Abstract: This paper describes how the current pulse ratings of thyristors during turn-on spreading can be obtained from the maximum allowable junction temperature based on time-to-failure using a combination of analytical and experimental methods. The instantaneous junction temperature rise of a thyristor is analyzed with the aid of a digital computer. In the calculation of temperature rise, the transient thermal impedance during turn-on spreading is considered. Analyzed results agree with the values obtained directly by an infrared detector. In order to estimate the maximum allowable junction temperature based on time-to-failure, "step-stress capability tests" were conducted. In many cases, it was found that there were modes of both catastrophic and degradation failure. The maximum allowable junction temperature was estimated for the nonrepetitive and repetitive current pulse ratings.

22 citations


Patent
28 May 1970
TL;DR: A plurality of alternating junctions of two types arranged in a series configuration is considered in this paper. But the effect is the cumulative Peltier effects produced at the first type of junction.
Abstract: A plurality of alternating junctions of two types arranged in a series configuration. The first junction type is comprised of two materials in overlapping arrangement. The second junction type is also comprised of two materials and additionally has a third material therebetween. Current flow through the junction produces a Peltier heating or cooling effect at the first type of junction. Either no thermal effect or both Peltier heating and cooling occur at the second type of junction which cancel out. The effect is the cumulative Peltier effects produced at the first type of junction.

17 citations


Journal ArticleDOI
TL;DR: In this article, the authors describe a system that provides accurate contact surface-temperature measurement that is free from conduction error and heat perturbation of the measured surface using an electronically servoed backup heater.
Abstract: A system is described that provides accurate contact surface-temperature measurement that is free from conduction error and heat perturbation of the measured surface. The principle is one of null heat flow provided by an electronically servoed backup heater. The probe consists of three basic parts: a measuring contact thermocouple, a differential thermocouple, and a heater, mounted in tandem. The measuring junction and one junction of the differential couple contact the surface. The second differential junction is located a short distance behind the first junction so as to have a thermal path between the junctions. The backup heater is located behind the second junction. When the probe contacts a surface that is above probe temperature, the first differential junction rises in temperature above the second junction, producing an EMF which is fed into the electronic servo. This signal is amplified, and quickly energizes the electric backup heater by the amount required to reduce and maintain the differential signal at zero. Under this condition, there is no heat exchange between the probe and the surface; the measuring junction is at the surface temperature. Present temperature capability extends from ambient to approximately 2250°F. Future designs are expected to extend the upper limit to about 3000°F.

3 citations


Journal ArticleDOI
TL;DR: In this paper, the forward voltage drop (V f) of an ac operating triac was used to indicate its junction temperature, and the indicated temperature was in excellent agreement with the maximum temperature measured with an infrared microradiometer at the surface of the active region of the triac.
Abstract: The forward voltage drop V f of an ac operating triac can be employed to indicate its junction temperature. The V f , for a constant test current, is shown to decrease linearly with increasing temperature over the range of 20 to 125°C with measured slopes between -1.4 to -1.6 mV/°C. A sampling current must be used at the end of an applied power pulse and the cooling of the triac which takes place during the delay in measurement is taken into account by an extrapolation procedure. The indicated temperature using the V f method is in excellent agreement With the maximum temperature measured with an infrared microradiometer at the surface of the active region of the triac. The V f technique requires a special power test circuit which is described. This technique provides an accurate indication of the maximum operating temperature and requires calibration of only a few triacs. Triac manufacturers can use the V f technique to accurately measure the thermal performance of their triacs and to screen production to eliminate marginal devices.

3 citations


Journal ArticleDOI
TL;DR: In this article, the threshold gate trigger current (I GT) was used to indicate the junction temperature of an ac operating triac, and the I GT was found to have more consistent temperature dependence than that of third-quadrant gating.
Abstract: A description is given for the use of the threshold gate trigger current (I GT ) of an ac operating triac to indicate its junction temperature. Because of different triggering mechanisms, the I GT of the first-quadrant gating has been found to have a more consistent temperature dependence than that of third-quadrant gating. The temperature dependence of I GT can be described by an empirical formula of the form I_{GT} = I_{GT_{0}} \exp [-a(T - T_{0})] over the temperature range 25 to 125°C. The device constant a is generally of the order of 0.007 to 0.009 (°C)-1. Junction temperature measurements can be made for a device during either the cooling or the heating period using the threshold gate trigger current as a temperature-sensitive parameter. Temperatures indicated by this technique are compared to surface temperatures measured directly with an infrared microradiometer. The gate trigger current has been found to be an easy parameter to measure for triacs in a self-gating circuit during transient or steady-state operation; therefore, it can provide triac users with a convenient and relatively accurate method of evaluating the thermal performance of their triacs.

3 citations