Design of Alloyed Junction Germanium Transistors for High-Speed Switching

The present trend in switching systems and computers is toward systems that operate at megacycle rates with pulse rise times in the vicinity of a tenth of a microsecond. In the attendant design of pulse-amplifiers, pulse-generators, and flip-flops there has arisen the need for high-speed junction transistors, particularly in cases where the device must switch high currents for extended periods of time. Roughly, devices are needed with alphas greater than 0.95 and frequency cut-offs of alpha in the range of 10 to 50 mc per second. In considering transistor structures for high pulse rate systems there are several contenders for further development, for example, grown-junction triodes and tetrodes, alloyed-junction triodes, and intrinsic-barrier transistors. 1 A comparison has to be made of the design possibilities and the relative merits of these devices when used as switches. The objective of this paper is to determine the applicability and limitations of alloyed-junction transistors in high-speed switching applications. Many of the considerations in the design of alloyed-junction transistors for switching are also important in largesignal transmission applications. Alloyed junctions transistors have been extensively used in switching systems having a pulse rate below a megacycle per second with excellent 761