Majority switching device with ohmic summing input network - has transistor comparator and dual transistor constant current sink

摘要

A majority switching arrangement consists of a summing network with a number of ohmic resistors corresp. to the number of inputs and a comparator with fixed defined switching levels receiving inputs from the summing network. The arrangement provides sufficiently different control signals relative to the comparator switching conditions despite the unavoidable component tolerances. The resistors (R1-R5) forming the inputs (E1 to E5) of the summing network are simultaneously connected to a constant current sink and to the input of the comparator (T3). The constant current sink consists of a current mirror circuit contg. two transistors (T1, T2) and two resistors (R6, R7) the collector circuit of the second transistor. If two or more high levels are applied to the inputs, the comparator transistor (T3), is on and if two or more low levels are applied it is off.