| 摘要 |
PURPOSE:To design a circuit without considering the logical change of the output of the FF circuit of a scan-path shift register by providing a circuit which holds the value of the output of the FF circuit. CONSTITUTION:Flip-flop(FF) circuits F1-F3 operate as the shift register by controlling selector circuits S1-S3 with a signal from a select terminal I2. The FF circuit F1 has a data input terminal D, an output terminal Q, a set terminal S, and a clock terminal, and the FF circuits F2 and F3 have input terminals D, output terminals Q, and clock terminals. Then when there is a signal which allows the FF circuits to operate as the shift register from the terminal I2, the value is held in holding circuits T1-T3 connecting with input terminals D of the FF circuits F1-F3 other than signal lines L1-L3 connecting with input terminals D of the FF circuits F1-F3 throughout shifting operation. Namely, a logic circuit part LO2 connecting with the outputs of the FF circuits F1-F3 does not require circuit constitution in which the shifting operation is considered. |
