The present invention reduces the area on a die required for rows and columns
of redundant memory cells by sharing compare circuitry with banks of redundant
memory cells based on division of the primary memory array into two or more "planes."
Pass gates or multiplexers coupled between at least two banks of fuses and one
compare circuit selectively couple the appropriate fuse bank to the compare circuit.
Preferably, a bit in the address (e.g., address bit RA9 in a row address
word having address bits A0-RA9) is received by and controls the
multiplexer to select between the two banks of fuses. Additionally, the planes
span blocks of memory in the memory array, where each block is divided by shared
sense amplifiers. As a result, while eight lines are coupled to 16 rows or columns,
only eight rows or columns will be active at any one time because isolation gates
will enable only eight of the 16 rows or columns within two planes of memory. As
a result, the present invention saves on the number of lines required to intercouple
the compare circuits to the redundant rows/columns.