| 摘要 |
PURPOSE:To prevent the malfunction of a redundant decoder by generating a signal for activating the redundant decoder based on an internal signal. CONSTITUTION:At the time of using a redundant column recorder 21, a fuse 11 is fused by a laser or the like. A signal, the inverse of RAS is trailed, the input of the input terminal (a) of a NAND gate 1 goes to an H level by an inverter 2 and the input of the other input terminal (b) of the gate 1 is delayed by a fixed time from the signal, the inverse of RAS by inverters 4, 5, 6, 7 to be an L level. In this case, the output of the output terminal (c) of the gate 1 goes to the L level only for the delay time. Then, the potential of a point (d) goes to 'H' by a p, the inverse of FET 8. Thereby, p, the inverse of FET 9 is turned on by an inverter 13, the output of the terminal (c) goes to 'H' and even when the FET 8 is turned off, the potential of the point d maintains 'H'. Accordingly, a redundant decoder activating signal SDE continues the state of 'H' and the redundant column decoder 21 is activated.
|
