Logic circuit having error detection function, redundant resource

Abstract

A self-checking circuit, which is useful for a highly reliable system configuration, includes a logic circuit having an error detection function. For function blocks for feeding out a plurality of signals that are at least duplexed, the logic circuit compares the output signals of the function blocks, and detects an error on the basis of results of the comparison. The logic circuit comprises synthesizing means provided to superimpose inherent waveforms assigned in advance to the respective output signals of the function blocks onto the output signals of one of the function blocks. The inherent waveforms are orthogonal waveforms generated by an orthogonal waveform generator circuit. The logic circuit also comprises comparison means for comparing a signal output of the synthesizing means with the signal output of the other function block to detect an error. The whole circuit including the function blocks are judged normal only if the waveforms inherent to both output signals exist.