Showing papers on "Junction temperature published in 1979"

Accelerated aging test of Ga1−xAlxAs DH lasers

Abstract: An accelerated aging test is performed at temperatures of 70, 110, and 140 °C to estimate the activation energy Samples are operated in the LED mode at high temperatures of 110 and 140 °C At 70 °C samples are operated in lasing mode of optical output 027 mW/μm The laser lifetime is defined to be a time at which the cw threshold current measured at a standard temperature 25 °C reaches 15 times the initial value The activation energy 074 eV is obtained It is shown that the degradation does not depend on the optical output power below the power level of 03 mW/μm and that the activation energy is indifferent to the operation mode, LED mode, or lasing mode, at a low power level The use of the LED mode operation and the definition of the laser lifetime in terms of the characteristics at low standard temperature enable one to perform the accelerated aging test at high temperatures above 110 °C where cw operation is almost impossible The reliability is examined at 70 °C using 50 samples and an average laser lifetime is obtained The application of the activation energy gives the average laser lifetime at the junction temperature of 30 °C to be 3×105 h

Analysis of a heat exchanger - Thermoelectric generator system

Abstract: Analysis of a thermoelectric generator (TEG) in an ocean thermal energy conversion (OTEC) application is presented. An analytic model is developed for describing the heat exchanger-TEG interactions. This model is used to illustrate limitations of applying conventional fixed junction temperature assumptions to systems experiencing significant temperature drops across the heat exchanger surfaces. Design methods are developed for determining the thermoelectric element geometry that produces maximum output power. Results show that a heat exchanger-TEG system may deliver about 100 W/m/sup 2/ of heat exchanger surface. This compares favorably with conventional OTEC schemes.

Bipolar Microwave Linear Power Transistor Design

Abstract: Design considerations for n-p-n bipolar microwave linear power transistors are discussed. Optimization procedures are presented for determining emitter width for a specfic operation frequency, emitter ballasting resistance, and active area geometry based on calculated temperature distributions. A transistor chip designed for 4-GHz operations using these procedures achieved a linear power output of 27.5 dBm at a 1-dB compressed gain of 7 dB with a power added efficiency of 23 percent. Junction temperature rise was limited to 90/spl deg/C.

Analysis of a heat exchanger-thermoelectric generator system

Abstract: Analysis of a thermoelectric generator (TEG) in an ocean thermal energy conversion (OTEC) application is presented. An analytic model is developed for describing the heat exchanger-TEG interactions. This model is used to illustrate limitations of applying conventional fixed junction temperature assumptions to systems experiencing significant temperature drops across the heat exchanger surfaces. Design methods are developed for determining the thermoelectric element geometry that produces maximum output power. Results show that a heat exchanger-TEG system may deliver about 100 W/m/sup 2/ of heat exchanger surface. This compares favorably with conventional OTEC schemes.

Interface circuit for interconnecting an electronic controller to a resistance welding machine

Abstract: An interface circuit is provided for interconnecting an electronic controller to a contactor circuit which, in turn, controls the alternating current flow from an alternating current power source to controlled equipment, such as a resistance welding machine. The contactor circuit, for example, includes a pair of semiconductor switching devices, such as silicon controlled rectifiers (SCR)s, the two semiconductor switching devices are alternately rendered conductive during successive half-cycles of the alternating current power from the alternating current power source at times controlled by the controller for the controlled operation of the welding machine. The interface circuit includes means for monitoring the junction temperature of each of the semiconductor switching devices, and to provide an indication and a control effect should the junction temperature exceed a particular safe threshold.

Temperature control unit of semiconductor laser element

Abstract: PURPOSE:To perform temperature control for the LD element, by utilizing the forward voltage of LD element related to the junction temperature of LD element. CONSTITUTION:When the switch. conduct 31 is closed, the LG element 26 is sufficiently contacted and oscillated, and when the contact 30 is closed, the power application is insufficienct for the oscillation due to the resistor 28. With the terminal voltage of element by the circuit 32, the junction temperature and the standard operating temperature are compared and the control signal is fed to the temperature control circuit 33. The circuit 33, in case of cooling, feeds power to the peltier element via the terminal plates 21 and 23. Thus, LD is cooled by Peltier effect. When heating LD, the direction of power application of the element 22 is inversed. Thus, the junction temperature of LD element actually can quickly be detected and the temperature control of LD can be made.

The thermal properties of a single-heterostructure laser diode supplied with short current pulses

Abstract: The analysis of the heat spreading in the single-heterostructure GaAs-Ga1-x Al x As laser diode supplied with short current pulses (in the case, however, when the adiabatic approximation is no longer valid) at room temperature is presented in this paper. Relations are derived, describing the time-dependent temperature rise within the volume of the laser diode. The calculations are carried out for a typical SH laser diode. It turns out that in the duration of the short current pulses (t I=200 ns,j=1.5 × 104A cm−2) the increase in junction temperature of the typical SH laser diode amounts to about 6.1 K. This increase leads to an increase of about 9% in the threshold current, to a decrease of about 18% in the laser radiation intensity, and to a shift of the spontaneous radiation band and of the stimulated radiation modes of about 1.9 nm and 0.22 nm, respectively, during each current pulse.

D.C. characteristics of silicon p-n junctions at avalanche breakdown including selfheating☆

Abstract: The computation of the dc characteristics of a silicon p - n junction at breakdown is described in this paper In the analysis, the effect of the dissipated electric power on the junction temperature is taken into account The influences of the thermal resistance, the ambient temperature and the low-voltage reverse current on the dc characteristics at breakdown are shown A formula describing the differential resistance of a junction at breakdown is derived The temperature coefficients of voltage and current for the dc characteristics under consideration are derived as well The coordinates of the points at which these coefficients change the sign are calculated and the influence of the thermal resistance, the ambient temperature and the low-voltage reverse current on the coordinates of these points is discussed

Thermal properties of semiconductor lasers, and the interpretation of thermal-resistance measurements

Abstract: Conventional models of junction heating in semiconductor lasers have been considered, and are found to be inconsistent with the experimental observations on stripe-geometry double-heterojunction lasers. In particular, the onset of the thermal runaway of c.w. threshold current, induced either by increasing the heat-sink temperature or by degradation processes, is found to occur at a current much less than predicted theoretically. Part of the reason for these inconsistencies is that at high temperatures there is a departure from the commonly assumed exponential dependence of pulsed threshold on junction temperature. However, it is the observation that the temperature rise of the active region is not directly proportional to the input power which explains why the experimental results are so different from the theoretical predictions. The results are discussed with reference to a model of multiple heat sources, with sources assuming different relative importance as the input power increases.

Semiconductor memory unit

Abstract: PURPOSE:To perform the test and diagnosis with the condition of high temperature furnace not changed as normal use, by performing the information reproducing operation concentratingly and continuously, in increasing the junction temperature of each semiconductor memory element to a given temperature simultaneously CONSTITUTION:Among the memory elements in the memory section constituted with m X n sets of elements, only m sets consume greater power with normal readout and write-in, and the remaining m(n-1) sets only consume the leakage current at non-operation Thus, the junction temperature internal the elements can not be increased, unless the readout or write-in is continued especially to the address for a part concentratingly Accordingly, in the memory control section 2, the concentration type reproduction operation circuit 13 is provided, and at the test and diagnosis of the dynamic MOS type memory unit 1 only, the concentrating type reproducing operation is made with the instruction from CPU 3 to increase the junction temperature in the unit 1, and after that the diagnosis of the unit 1 is made Thus, the equivalent test at that at high temperature can be made

Experimental Investigation of Mounting Thermal Resistance of Flatpacks on Circuit Boards

Abstract: Thermal tests were performed on radar digital module circuit boards to measure the thermal effect of various size gaps between the circuit board and the flatpack integrated circuit (IC) case and also the thermal resistance of the circuit board. These IC's are cooled by conduction through the circuit board to. an air-cooled heat exchanger. The thermal effect of the gap filled with air, and also filled with an adhesive, was measured. The temperature differences between pairs of locations on the flatpack IC case, particularly between the top and the bottom center, also were measured. These tests are described; the test results are presented, discussed, and compared with analytical predictions; and conclusions are given. The key conclusions are that the filler is quite effective in lowering the IC junction temperatures and, in fact, has a larger thermal effect than the gap size. For example, filling a 5-mil (1.27 x 10-4m) gap reduces the junction temperature by 12°C, whereas reducing the gap from 5 mils (1.27 x 10-4m) to 0 reduces it by only 3°C. The combined thermal resistance of the gap and the circuit board is a linear function of the gap.