Two-level ecl multiplexer without emitter dotting

Abstract From the Canadian patent

A two-level 4:1 ECL multiplexer circuit comprising two 2:1 multiplexer circuits "OR'd" together prior to a shared output stage. A differential Select line, operable at the same voltage level as the input data lines to the 2:1 multiplexer circuits selects one of the input lines to each 2:1 multiplexer circuit. A second Select line, operable at a different voltage level, selects one or the other of the 2:1 multiplexer circuits. This arrangement functions to eliminate an undesirable glitch observed when selecting data inputs in known two-level, 4:1 multiplexers which use emitter dotting.