Millimicrosecond transistor current switching circuits

If transistor switching circuits are to be developed having response times limited by the bandwidths of the transistors operating as amplifiera and by diffusion or transit time delay, it becomes necessary to avoid operation in saturation. Since a low collector-to-base voltage has a detrimental effect on transistor bandwidths, it is desireable, as well, to avoid operation near saturation. A technique has been developed for the design of non-saturating transistor circuits where weil specified currents are switched with small associated voltage swings. The basic principle of the mode of operation is the switching of a constant current from the emitters of one group of transistors into the emitters of another group of transistors. Logical outputs are taken from parallel combinations of transistor collectors. The resulting logical circuits reset their own levels.