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 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 method for testing a semiconductor device including first and second power source lines, a plurality of output circuits, and a plurality of output terminals each disposed for one of said 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, said first node being connected to a corresponding one of said output terminals, said method comprising:
controlling said output circuits to turn ON said first and second transistors of a first output circuit among said plurality of output circuits, to turn ON one of said first transistor and said second transistor of a second output circuit among said plurality of output circuits, and to turn OFF another of said first transistor and said second transistor of said second output circuit;
measuring a potential difference between said output terminal of said first output circuit and said output terminal of said second output circuit and a penetrating current flowing through said first and second transistors of said first output circuit; and
calculating a characteristic of one of said first transistor and said second transistor of said first output circuit, based on said potential difference and said penetrating current and which of said first transistor and said second transistor of said second output circuit is ON.
2. The method according to claim 1 , wherein at least one of said first and second transistors comprises a plurality of transistor elements connected in parallel, and a specified number of said transistor elements among said plurality of transistor elements are turned ON during said controlling.
3. The method according to claim 1 , further comprising: selecting an arbitrary two of said plurality of output circuits as said first and second output circuits, before said controlling.
4. The method according to claim 1 , wherein said controlling uses external pins of said semiconductor device to turn ON said first and second transistors of said first output circuit and to turn ON/OFF said first transistor and said second transistor of said second output circuit.
5. The method according to claim 1 , wherein said measuring uses a constant current source connected between said first power source line and said second power source line.