Showing papers on "Junction temperature published in 1982"

Microprocessor controlled thermocouple simulator system

Abstract: A thermocouple simulator system which is capable of generating a voltage equivalent to the EMF output of a thermocouple of a selected type at a specified sensing junction temperature. The system includes a keyboard which allows an operator to specify a sensing junction temperature, voltage, thermocouple type, reference junction temperature, and whether a pair of output terminals of the system perform as thermocouple alloy or copper. Using an operation program, a microprocessor calculates the thermocouple EMF using a stored temperature versus EMF polynomial function of the selected thermocouple type. The microprocessor then causes a voltage simulating the calculated EMF to be applied to the output terminals utilizing a reference voltage source, digital-to-analog converter (DAC), and output amplifier. When the wires connected to the output terminals are made of a different metal than the terminals, signals from temperature sensors in the output terminals are fed to the microprocessor through an analog-to-digital converter. The microprocessor then offsets the voltage simulating the EMF output to compensate for the thermocouple junction formed in connecting the wires to the output terminals. The system may also operate as a precision DC power supply with extremely low output impedance.

Heat response compensating system for light emitting diode

Abstract: PURPOSE:To prevent the deterioration due to variation in the temperature by varying the diode drive current by the junction temperature detected by the forward voltage of a light emitting diode. CONSTITUTION:A light emitting diode (LED) 4 is driven by a gain variable amplifier 1, and LED drive circuits 2, 3, and jigs junction temperature is detected by a junction temperature detector 5. The detector 5 has a resistor Ri, connected in series with the LED 4, a resistor R, a diode D, and an operational amplifier 6, and the junction temperature is detected by the forward voltage of the LED 4. The detected temperature signal is fed through a voltage control operational amplifier 7 to a gain variable amplifier 1, thereby controlling the drive current of the LED 4. Thus, the nonlinearity between the light emitting power and current of the LED 4 can be improved and the deterioration of the characteristics can be prevented.

Gallium Arsenide IMPATT Diodes At 20 GHz

Abstract: High performance double-drift Read GaAs IMPATT diodes have yielded power levels of 4 W CW with 20 percent efficiency at 20 GHz with a junction temperature less than 250° C. In this paper we describe the profile, chip and thermal design of such diodes. It is shown that further improvements in thermal design should result in diodes giving up to 8W CW. Electrical series resistance and package parasitics are important parameters in determining the device performance and amplifier bandwidth. We show that there need not be a tradeoff between thermal and parasitic characteristics of a 20 GHz diode package.

Testing method for transistor

Abstract: PURPOSE:To know the junction temperature of a transistor (TR) to be tested easily and accurately during its intermittent operation test by measuring the emitter-base forward voltage and then using temperature characteristics of a calibrated emitter-base forward voltage for the test. CONSTITUTION:A backward bias from a collector power source 6 is applied between the collector 2 and base 3 of a common base TR1 to be tested, and a switch 5 is put in operation by an emitter power source 7 to apply a forward bias to the base 3 and emitter 4 intermittently. The VEB at the moment when the TR1 turns on is VEB1, and the VEB right before it turns off is VBE2; and the temperature coefficient of the VEB is alpha, and the VEB when Tj=20 deg.C is VEB0, obtaining the maximum temperature Tjmax and minimum temperature Tjmin of the junction and variation DELTATj in junction temperature as shown by equations. Consequently, the junction temperature of the TR to be tested during its intermittent operation test is known easily and accurately.

Modular SCR Assemblies in VSCF Systems

Abstract: The success of the cycloconverter based VSCF electrical system has clearly been dependent upon the development of the silicon-controlled rectifier (SCR) as a high power electrical switch. The purpose of this paper is to describe the innovative work in process to improve the thermal characteristics of the SCR; and, thereby, improve the cycloconverter power quality and efficiency. The key parameter to improvements in the SCR performance is to reduce the thermal impedance from the semi-conductor junction to case. By improving this characteristic, lower junction temperature or smaller devices may be used in a given application. Significant improvements in this area, for 18 mm SCR pellets and larger, have been severely limited by the necessity for dry interfaces. Up to now, the thermal stresses developed at the silicon-copper interface during low temperature excursion preclude solder or other direct bonding techniques. The unique approach described in this paper eliminates the dry interface, incorporates built-in electrical isolation, and features structured copper, solder bonding, direct bond copper on beryllia, and a hermetic-sealed aluminum enclosure.

Joining method of ferrite

Abstract: PURPOSE:To easily execute junction, by combining and holding a single-crystalline ferrite body and a polycrystallie in ferrite body, placing them in an atmosphere containing oxidizing gas in said state, and holding them at a high temperature. CONSTITUTION:The respective junction surfaces of a single-crystalline ferrite body 1 and a polycrystalline ferrite body 2 are polished by a grind-stone of #600, and after that, these junction surfaces are butted, and are placed in a high- temperature oxidizing atmosphere of 10% oxygen partial pressure and 1,300 deg.C junction temperature. Subsequently, said state is held for 0.5hr, by which diffused junction is executed between the junction surfaces of both the single-crystalline ferrite body 1 and the polycrystalline ferrite body 2. In this way, it is unnecessary to take time for finishing the junction surface, and also to perform pressing, therefore, junction of ferrite can be executed very easily.

Measuring method of thermal resistance

Abstract: PURPOSE:To derive thermal resistance of a semidoncudtor chip, by deriving a temperature coefficient showing the ratio in which forward voltage of rectifier junction in the semiconductor chip is varied in accordance with a variation of a junction temperature, from a value of the forward voltage at a prescribed temperature, and utilizing it CONSTITUTION:A variation DELTAVF/DELTAT of forward voltage VF following a variation of a temperature is measured by use of a Ga As FET by which the forward voltage at a normal temperature is distributed to about 05V-08V, and is plotted against the forward voltage VF There is a linear correlation between both of them A temperature coefficient of its element can be grasped by utilizing said correlation and measuring the forward voltage VF at a normal temperature, and subsequently, a temperature of a heating part and thermal resistance of a device can be grasped by measuring the forward voltage VF at the time of heating

Measuring method for thermal resistance of gate turnoff thyristor

Abstract: PURPOSE:To reduce the ununiformity of a measured value and of the inclination of a calibration curve and thereby to improve the reliability of the measurement of the rise in a junction temperature, by making a calibration current flow only through one p-n junction of the GTO thyristor. CONSTITUTION:In the case when the calibration current is to be found, the calibration current is made to flow from a power source 6 for the calibration current to between the gate and cathode of the GTO thyristor under the condition that a switch S is opened in a constant-temperature tank and the fall of a forward-direction voltage caused by the calibration current between the gate and the cathode is measured. In measurement of the thermal resistance, first the calibration current is made to flow between the gate and cathode of the GTO thyristor 5 under the condition that the switch S is opened and the fall of the forward-direction voltage and the base temperature are measured. Next, the switch S being closed, the base current and the fall of the forward- direction voltage at the time when the current and the temperature are stable are measured by a detecting circuit 8, and the thermal resistance is calculated from the calibration curve. Since the calibration current flows only through the p-n junction of the GTO thyristor 5 in this method, the ununiformity of the measured value is little and thus the reliability of the measurement can be improved.

High frequency high power transistor

Abstract: PURPOSE:To stably and uniformly operate transistor cells in a parallel operation by forming diodes in the respective base regions forming the respective transistor cells to compensate the temperature. CONSTITUTION:A P type base region 22 is provided in contact with an N type collector region 21 in a semiconductor chip 11. Then, an emitter region 23 and the same conductive type region 15 as the region 22 at an interval from the region 23 are formed in the region 22. The depth of the region 25 is formed three times the depth of the region 22. The same conductive type region 26 as the region 23 is formed in the region 25, and a diode is formed (o) the regions 25, 26. Then, an insulating film 27 is formed, is opened, and base electrodes 28, 28' and emitter electrodes 29 are formed, and the surface is covered further with an insulator 30, windows for bonding pads 31, 32 are opened, and leading electrode 13 is formed. Thus, the temperature of the junction of the diode and the temperature of the emitter and base junction temperature of the corresponding transistor cell become equal, and the emitter current can be constant with respect to the variation in the temperature of the junction.

Precision Temperature Profiling in Highly Accelerated VLSI Life Test

Abstract: Discrete devices under high electrical stress can produce nonuniform junction temperature in a chip. Knowledge of precise junction temperature is essential for accurate reliability projection, since most failure mechanisms are highly temperature activated. Thermal conduction equations are solved analytically with appropriate boundary conditions for junction temperature calculation. Experiments performed on test chips show good correlation.

Practical PIN Diodes

Abstract: The selection of a PIN to perform a particular microwave switching function begins with the choice of the size of the I region — specifically, its thickness, W, and cross sectional area, A. In practice, however, this characterization is usually accomplished using the related variables junction capacitance, CJ, which depends upon both A and W, and bulk breakdown voltage, VBB, which is proportional to W. What are the basic considerations in making these selections?