SHIFT REGISTER SERVING BOTH LATCH MODE AND COUNTER MODE AND FLASH MEMORY UTILIZING THE SHIFT REGISTER

摘要

PROBLEM TO BE SOLVED: To reduce the count of internal circuits and make a memory highly integrated by letting a shift register circuit carry out both a latch operation and a counter operation. ;SOLUTION: A latch part of a front stage consisting of a NAND circuit 1, an inverter circuit 2 and a switch S3, and a latch part of a rear stage consisting similarly of a NAND circuit 3, an inverter circuit 4 and a switch S5 are connected with each other via switches S2 and S4 in a shift register circuit SF1. Switches S1 and S6 are controlled to be opposite phases by a switch signal command. When the circuit functions as a latch circuit, the switch S1 is turned ON and the switch S6 is turned OFF, thereby simply latching an input INA. On the other hand, when the circuit works as a counter circuit, the switch S1 is turned OFF and the switch S6 is turned ON, thereby constituting a feedback loop and carrying out a count-up operation by a clock signal CLK and an inverted clock signal CLKB.;COPYRIGHT: (C)1998,JPO