Test 0/ a structured circuit Two full-adders (FAI and FA2) are connected in series as shown in Figure 13.22. This structured circuit adds two 2-bit numbers, (al, a2) + (bI , b2), and produces a 3 -bit result, (SI, S2, S3). An input carry cO (set to ° in our case) can be used to put in cascade several circuits, in order to constitute an n-bit adder.

We suppose that each full-adder is completely tested by the following test sequence made of 5 input vectors

(a,

b, c) : .

1. Is it possible to apply such a sequence to each module from the primary inputs and outputs?
2. From this study, deduce a complete test sequence that ensures the detection of all faults in this circuit.

Transcribed Image Text:

c0 SI FAI 11 cl S2 FA2 83 al bl a2 b2 Figure 13.22. Structured adder