| 摘要 |
PURPOSE:To replace simply a defective circuit by a method wherein the output of the defective circuit or a design change circuit is inputted in one side of the switching gate means of the defective circuit, the output of the normal circuit is added to one side of the cut-off means of the normal circuit and bias is added to the other side of each of both switching gate means from the bias means. CONSTITUTION:The output of a defective circuit 2a and the output of a normal circuit 2b are respectively added to the input terminal on one side of each of NOR gates 3a and 3b, each input terminal on the other side is connected to pads 4b and 4d and the output terminals of the gates 3a and 3b are respectively connected to pads 4a and 4c. The circuits 2a' and 2b' of a chip 1b are respectively connected to pads 5a and 5f, pads 5b and 5d respectively to the bias circuits 6a and 6a' of the H level and pads 5c and 5e respectively to the bias circuits 6b and 6b' of the L level. The pads 4a and 5a, the pads 4c and 5f, the pads 4b and 5b and the pads 4d and 5e are connected to each other. When the bias of the H level is added to the 5b, the defective circuit 2a is switched, and when the bias of the L level is added to the 5e, the output terminal of the NOR gate 3 is connected to the circuit 2' on the following stage and the defective circuit 2a is replaced with a normal circuit 2a'. The bias of the L level can be added to the 5b from a circuit 7 using an inverter AND gate 3a' of an negative logic instead of the NOR gate 3a. |
