1. A circuit arrangement comprising a plurality of signal paths which are formed by active circuits and by means of which signals of different levels are applied to a common output, each signal path being activatable by a switchable current source, characterized in that: (a) each current source is formed by at least one I.sup.2 L gate (3a to 5b); (b) the I.sup.2 L gates are divided between a first group and a second group, the injector connections of the first group being connected to a first junction point (A) while the injector connections of the second group are connected to a second junction point (B); (c) the control inputs of the I.sup.2 L gates (3a to 5b) are driven so that when a switch-over occurs from one signal path to another signal path, two I.sup.2 L gates, each of which is associated with one of the signal paths and with one of the groups (for example, 3b, 4a), can conduct current at least during a transition phase; and (d) the junction points (A, B) are chosen so that the output currents of the two I.sup.2 L gates vary continuously and in the opposite sense during the transition phase.