Semiconductor device having a test circuit for testing an output circuit
View Patent ↗A method for testing an output circuit of a semiconductor device including a plurality of output circuits includes the step of s turning ON p-ch and n-ch MIS transistors of a subject output circuit, turning ON and OFF one and the other, respectively, of p-ch and n-ch MIS transistors of another output circuit used as a reference output circuit, measuring the potential difference between the output terminal of the subject output circuit and the output terminal of the reference output circuit and the penetrating current of the subject output circuit, and calculating the ON-resistance of the p-ch or n-ch transistor of the subject output circuit.
1. A semiconductor device comprising:
first and second power source lines;
a plurality of output circuits including at least first and second output circuits, each of said output circuits including a combination of first and second transistors connected together in series via a first node and between said first power source line and said second power source line;
a plurality of output terminals each disposed for one of said output circuits, said first node being connected to a corresponding one of said output terminals; and
a control circuit for controlling said output circuits during a test mode to turn ON said first and second transistors of said first output circuit, to turn ON one of said first transistor and said second transistor of said second output circuit, and to turn OFF another of said first transistor and said second transistor of said second output circuit.
2. The semiconductor device according to claim 1 , wherein said control circuit turns OFF said first and second transistors of all said output circuits other than said first and second output circuits.
3. The semiconductor device according to claim 1 , wherein said first and second transistors comprise p-ch and n-ch MIS transistors, respectively.
4. The semiconductor device according to claim 1 , wherein at least one of said first and second transistors comprises a plurality of transistor elements connected in parallel.
5. The semiconductor device according to claim 1 , wherein said control circuit comprises a decoder for decoding external signals to deliver a control signal for controlling said output circuits.
6. The semiconductor device according to claim 5 , wherein said control signal selects a potential to be provided to control electrodes of said first and second transistors.
7. The semiconductor device according to claim 1 , further comprising:
a functional circuit block connected between said first power source line and said second power source line; and
a control switch for isolating said functional circuit block from said first or second power source line said test mode.
8. The semiconductor device according to claim 1 , wherein said first and second output circuits are connected between said first power source line and said second power source line via a common branch line extending from said first or second power source line.