Measurement of Internal Temperature Rise of Transistors

A method for measuring the internal temperature rise of a transistor, making use of the variation of alpha with temperature, is described. It consists of a comparison of static characteristics taken at constant temperature by means of a low-averagepower pulse technique and characteristics taken under continuous power dissipation. The advantage of the method lies in the fact that measurement is made at temperature equilibrium in the hottest portion of the transistor, and is made with current and voltage distributions essentially identical with those encountered in normal operation.