Abstract: A flip-flop circuit which requires only a small drive power and which operates with small power consumption, and in which the on-off transition occurs reliably. The flip-flop circuit comprises MOS field effect transistors (abbreviated as MOSFET's) and resistors. A first MOSFET and a second MOSFET, to which control signals are applied, are commonly-connected at their sources to be connected at the sources to a voltage source supplying a power supply voltage sufficiently higher than a threshold voltage of a third MOSFET and a fourth MOSFET interconnected to each other. The interconnected third and fourth MOSFET's are connected at their gates to the drains of the first and second MOSFET's, respectively, and to the drains of the fourth and third MOSFET's through resistors, respectively. The third and fourth MOSFET's are common-connected at their sources. An output terminal is led out from the drains of the first and third MOSFET's.

Abstract: A thyristor has a semiconductor body exhibiting an n-p-n-p layer sequence with the small n-emitter and the p-emitter being contacted by first and second electrodes. The p-base layer has a third electrode connected to the first electrode through a first current source connectible with a first polarity. For triggering or quenching the thyristor as quickly and efficiently as possible, the n-base layer has a fourth electrode connected to the second electrode through a second connectible current source, the second current source being connectible to the fourth electrode with a second polarity opposite the first polarity.