Abstract: A reference voltage source comprises a first current branch (16, 36) and a second current branch (30, 34, 12). The voltage on a first terminal (6) in the first current branch (16, 26) is one junction voltage higher than the voltage on a second terminal (8) in the second current branch (30, 34, 12) owing to the presence of a transistor (80). The ratio between the current I.sub.1 through the first current branch (16, 36) and the current I.sub.2 through the second current branch (30, 34, 12) is thus determined by two non-linear characteristics having opposite temperature coefficients. A reference voltage (v.sub.z) with a small temperature coefficient and with a value which can be chosen freely can be generated by an appropriate choice of the resistance values for the resistors (58, 30, 16, 12) and by scaling the emitter areas of the transistors (34, 36, 70, 80).

Abstract: A power transistor switching circuit includes a switching transistor. A switching signal triggers a control device which, via a delay device and a control amplifier applies a first control signal to a control electrode of the switching transistor. A thyristor is coupled to the control electrode of the switching transistor. The thyristor has a first trigger gate and a second trigger gate. A measuring circuit generates a measuring signal proportional to the current in the switching transistor. A comparison device compares the measuring signal with a reference signal for applying a second trigger signal to the thyristor second trigger gate. The control device includes a further control amplifier having an input coupled to the switching signal and an output which applies a further control signal to the first trigger gate. The delay device delays the first control signal with respect to the further control signal.