Multiplexing as generally defined, may be considered an operation which enables a plurality of individual items of information to be transmitted along the same transmission channel. The distribution of these items of information is performed as a function of a parameter which may be time, the frequency of the items of information, or their phase. In high-speed electronics, the field to wich the invention particularly relates, the controlling parameter is time. It may thus be assumed, by way of example, that in the case of digital information it is a question of performing the multiplexing operation on a certain number n of trains of binary logic signals U.sub.1, U.sub.2, U.sub.3, . . . U.sub.i, . . . U.sub.n of the same frequency F. Time multiplexing consists in transmitting over the selected single transmission channel, during respective time intervals .DELTA.T, each of the signals U.sub.1 -U.sub.n, T=1/F being the pulse period of the signal trains and n their number. The time .DELTA.T during which a signal is transmitted may be written .DELTA.T=T/n=1/nF.
It is convenient to represent the train of signals resulting from the multiplexing operation in the form of a logic equation, X=U.sub.1 X.sub.1 +U.sub.2 X.sub.2 + . . . +U.sub.i X.sub.i + . . . +U.sub.n X.sub.n, in which the parameters X.sub.1 to X.sub.n represent periodic logic signals which are of the value 1 during time .DELTA.T and which are relatively staggered by the same interval .DELTA.T.
The multiplexing operation referred to above is known and conventionally performed by logical circuitry in a so-called pulse-code-modulation or PCM system.
The logic circuits which are used to perform the multiplexing function, generally designed as gates, operate at a clock frequency which is the product nF of the number n of signal trains involved times the frequency F. The result is that the arithmetic throughput on the single transmission channel involved is limited by the maximum operating frequency of the logic circuits.
To increase this operating frequency, high-speed analog gates have been used in such processing systems; in an article published in Wissenschafliche Berichte-AEG Telefunken, vol. 48, 1975, No. 2/3, Berlin, a multiplexer is described for the processing of four trains of signals, incorporating switching gates consisting of two diodes each.