In this paper, two circuits are proposed to implement tri-state buffers/bus drivers for MOS Current-Mode Logic digital circuits. The first is a switch-based, fully differential circuit, while the second is a voltage follower-based, pseudodifferential circuit. In order to compare their performance, circuits are implemented in a 0.18\u03bcm CMOS technology, with the target data rate of 1Gbps over a 500\u03bcm long bus. Simulation results are compared also with a standard CMOS bus driver from a commercial cell library.