Path: utzoo!utgpu!watserv1!watmath!att!dptg!ulysses!andante!mit-eddie!snorkelwacker!usc!samsung!uunet!fernwood!portal!cup.portal.com!mmm From: mmm@cup.portal.com (Mark Robert Thorson) Newsgroups: comp.arch Subject: Re: Beating pinout by voltage domain multiplexing Message-ID: <31921@cup.portal.com> Date: 20 Jul 90 18:26:25 GMT References: Organization: The Portal System (TM) Lines: 29 An even better method of sending two signals down one line is to use thermoelectric drivers and receivers. In a thermoelectric circuit, heating or cooling is produced when current flows across a junction of dissimilar metals or semiconductors. The heating and cooling effects around the circuit add up to zero, of course. Whether heating or cooling will occur at a junction is controlled by the direction of current flow and intrinsic properties of the metals or semiconductors (properties which are related to the work function of the materials). The multiplexing is achieved with four states: +5 hot +5 cold 0 hot 0 cold Note that a junction between material A and material B which heats up when current I passes through it will cool down by an equal amount when current -I passes through it, hence the heating and cooling effects cancel when the signal takes a jog through another material, for example if the aluminum bond wire on one chip passes through a copper pc trace to connect to the aluminum bond wire of another chip. This means that the materials used for the pc traces, lead frame, bond wires, etc., can be disregarded. The only important junctions are those in the driver and the receiver. Oh yes, musn't forget this --> :-)