US Patent 7786749 Programmable integrated circuit having built in test circuit

A programmable integrated circuit has a plurality of logic elements with each logic element having a plurality of input leads and at least one output lead. The programmable integrated circuit further comprises a group of interconnect lines, and a first set of programmable circuits for electrically connecting the input and output leads of the plurality of logic elements to each other through the group of interconnect lines. The programmable integrated circuit further comprises a test circuit having at least one input and one output. Further the programmable integrated circuit comprises a second set of programmable circuits for electrically connecting the one output of the test circuit to the plurality of input leads of each of the plurality of logic elements and for electrically connecting the at least one output lead of each of the plurality of logic elements to the one input of the test circuit, through the group of interconnect lines.