SU957135A1 - Method of measuring avalanche transit time diod heat resistance - Google Patents

Description

(54) METHOD FOR MEASURING THERMAL RESISTANCE OF AVALANCHE MISSION DIODE

one

The invention relates to electronic engineering, primarily microelectronics, and can be used to measure the thermal resistance of avalanche-transit diodes (LPD) operating in a continuous mode.

Methods are known for measuring the thermal resistance of an LPD based on the experimental determination of the current-voltage characteristic of a diode and the temperature dependence of the breakdown voltage of its pn junction 1 - 3.

However, these methods for measuring the thermal resistance of the LPD do not provide satisfactory accuracy, since they are based on pulsed measurements of the heat-sensitive parameters of the LPD.

The closest technical solution to the invention is the method of measuring the thermal resistance of the LPD, which consists in passing a constant current through the device under test that corresponds to the avalanche mode modulated by low and high frequencies, the temperature of its case is measured, the differential resistance of the diode is measured at the modulating frequencies, the magnitude of the diode voltage and the slope of the temperature dependence of this voltage, from which the parameter value is calculated.

Measurements are made at a low constant current of the diode, when the temperature of the pn junction exceeds the temperature of the diode case by no more than 3-5 ° C, and the case temperature varies in the range of about 10 ° C, and the thermal resistance is calculated by the formula

ten

, . „)

where (Nd) „, (Kd) in –differential impedance of the diode, measured at low and high frequencies of the modulating signal, respectively;

Unp is the voltage of the avalanche breakdown of the LPD junction;

T is the device case temperature;

20 slope of the temperature dependence of the voltage

diode 4.

The known method of measuring RT has the following disadvantages:

1. To reduce the systematic error of measurements R. Additional research is needed to select the optimum diode supply current, the value of which must satisfy two contradictory requirements. On the one hand, the supply current must be as low as possible so that the diode does not change breakdown voltage, on the other hand, the supply current must be

as much as possible, in order to improve the ACCURACY of measuring the differential resistances (Pd), and (Cd), hence the thermal resistance of the diode. The found optimum diode current is usually in the interval between the minimum breakdown current of the pn junction and the starting current of the generation of microwave oscillations in the LPD. But even at the optimum supply current of the diode, it is impossible to completely eliminate the systematic measurement error R., the minimum value of which is 10 -12 ° / o, and the maximum - 250/0.

2. When calculating R by the formula (1), neither the magnitude of the diode supply current nor the total voltage drop across the diode, which determines the total heat produced by the diode, is taken into account. Due to these reasons, the systematic error in the determination of R LPD is increased.

3. With the optimum power current of the diode selected, the avalanche breakdown does not cover the whole of the junction, the pn junction, whose temperature is of the same order as the diode case temperature, i.e. the physical conditions under which the measurements are made. R, differ significantly from the operating conditions of the diode in the microwave devices, when the avalanche sample covers the entire area of the p – j junction, and its temperature exceeds the temperature of the diode case by 150–200 ° C. As a consequence, in the known device, the temperature dependence of the coefficients of heat and thermal diffusivity is not taken into account, which is important for an accurate estimate of the value of the limiting thermal power that can be dissipated in a particular LPD.

The aim of the invention is to improve the measurement accuracy.

The goal is achieved by the fact that according to the method of determining the thermal resistance of the LPD, which means that a constant current is passed through the device under test, which corresponds to the avalanche mode modulated by low and high frequencies, the temperature of its case is measured, the moduli of the diode are measured. frequencies, the diode voltage, and the slope of the temperature dependence of this voltage, from which the parameter value is calculated, measurements are made at a constant current corresponding to the mode of generation of the rated power by the diode.

The calculation of the thermal resistance value is produced by the formula

R (d) n- (d) v-2

 dUfl G., ... 1 p LT W

 Pe (rjs) h

where (R) H and (Ra) B are the differential resistances of the diode at low and high frequencies of the modulating signal, respectively:

Qc is the total voltage drop across the diode;

1p-constant operating current supply

diode;

T is the device temperature;

dU / dr is the slope of the temperature dependence of the total voltage drop across the diode.

The measurement accuracy of the proposed method is improved due to the fact that, at the operating current of the power supply, the PSD provides a uniform avalanche breakdown over the entire area of the pn junction at its operating temperature, and also the power dissipated on the device is more accurately determined, causing it to heat up. is determined by the total voltage drop across the diode, which is the sum of the average dc voltage falling on the drift space and the dc component of the voltage on the multiplication layer.

The second component of the total voltage drop across the diode is close to the voltage of the avalanche breakdown of the pn junction, which is measured in the known method.

In addition, the proposed method has the advantage that it allows measurements to be made directly in operating PSD circuits operating in both generation mode and amplification of microwave oscillations.

Claims (2)

Invention Formula The method for measuring the thermal resistance of an avalanche-transit diode, which consists in passing a constant current through the device under test, which corresponds to the avalanche mode modulated by low and high frequency signals, varies its body temperature, measures the differential resistance of the diode at modulating frequencies, the value the voltage on the diode and the slope of the temperature dependence of this voltage, from which a parameter value is calculated, characterized in that, in order to increase the accuracy, and Reproduction of the circuit is carried out at a constant current corresponding to the mode of generation by the diode of the nominal power. Sources of information taken into account in the examination 1. MS. Avoy V.R. Thermal resistance measurement of avalanche diodes. IEEE 957135, 5o Trans on Electron Dev., 1971, v. 18, No. 10.3 Patent of the GDR No. 89915, cl. 21 e 31/22, p. 973..1972. 2. Kenyon N, D. et ah Function-temperature resistance measurement in IMPATT diodes Elect. diodes, IEEE. Trans on Electron Dev., 1969, Letters, 1972, v. 8, No. 5, p. 118.5 v. 16, No. 5, p. 438 (prototype). 4. Haitz R. H. et al. A method for heat