JPS6426173A - Integrated circuit - Google Patents

Abstract

PURPOSE:To test a new circuit, and also, to reduce the area of an integrated circuit by superposing a testing circuit on a new logic circuit substrate and a substrate for loading an IC-converted logic circuit, and connecting the testing circuit and input/output terminals of the IC-formed circuit. CONSTITUTION:Circuits 7-9 are provided on the same substrate 17 as new logic circuits 4-6, and LSI-converted logic circuits 1-3 are provided on a substrate 18. Also, input/output terminals of the logic circuits 1-3 and input/ output terminals of testing circuits 7-9 are connected physically by terminals 10-15. The testing circuits 7-9 are constituted of a tri-state buffer, and constituted so that its output goes to a high impedance except the test time, and the LSI-formed logic circuits 1-3 and the new logic circuits 4-6 are connected substantially, by a selecting signal terminal 112. Also, said circuits are constituted so that output signals of the new logic circuits 4-6 are returned to the new logic circuits 4-6 through the testing circuits 7-9, at the time of testing.