A Decade Ring Counter Using Avalanche-Operated Junction Transistors

The avalanche mode of operation for junction transistors is encountered at higher-than-normal collector voltages. In this avalanche region of operation the electrical character of the junction transistor is profoundly altered because of a voltage sensitive current-multiplication occurring at the collector junction. Current controlled -type negative resistance characteristics suitable for bistable operation are obtained. Important features of these characteristics can be treated analytically to obtain results suitable for design purposes. Twelve experimental avalanche-operated junction transistors have been used in a decade ring counter and driver. This represents a saving of two-to-one in semiconductor devices, as contrasted to the use of conventially operated junction transistors for the same function. A like saving of other components is obtained. The ring counter uses a new method of count transfer which provides improved reliability and higher counting speed capability. The driver and counter achieve operation to 500 kilocycles using transistors having a frequency of cutoff in the range 30 to 40 kilocycles for conventional operation. The counter operates to 300 kilocycles over a temperature range from below 50° to 50°C without compensation or optimized design.