Logic redundancy circuit scheme

Abstract

A logic redundancy circuit scheme, comprising a plurality of pairs of logic circuit groups, each logic circuit group in a given pair having a respective logic node and a respective power control line, with each logic circuit group in a given pair generating substantially the same logic function signal on its respective logic node as the other logic circuit group in the given pair generates on its respective logic node. The circuit scheme further includes a plurality of isolation circuits having respective output nodes, with a different isolation circuit connected to each different logic circuit group logic node. These isolation circuits are powered at all times and each operates to provide an output signal on its output node indicative of the signal on the logic node connected thereto, while isolating the connected logic node from nets connected to the isolation circuit output node. The circuit scheme also includes means for electrically connecting together for bidirectional communication the logic nodes for each pair of logic circuit groups, prior to the connection to the isolation circuit associated therewith, and switching means connected to each of the power control lines associated with the plurality of pairs of logic circuit groups for providing power to one and only one logic circuit group in each pair of logic circuit groups. The circuit scheme also includes means for controlling, through the electrically connecting means, the logic state at the isolation circuit output node of the logic circuit group in a given pair of logic circuit groups, which is not powered, to have the same logic state as the isolation circuit output node of the logic circuit group in the given pair of logic circuit groups which is powered by the switching means, so that both isolation circuit output nodes in the pair provide a correct logic signal.