Bank selection structures for a memory array, including a flat cell rom array

Abstract

An integrated circuit memory comprises an array of non-volatile memory cells arranged in rows and columns, and including a plurality of banks. There are a plurality of word lines along the plurality of rows in the array, and a plurality of array bit lines arranged along the plurality of columns. The array bit lines extend across the array, and include sense lines and ground lines. A plurality of bank bit lines is arranged along the plurality of columns. The bank bit lines extend across corresponding banks in the plurality of banks and are coupled to memory cells in the corresponding banks. A plurality of connection terminals are coupled to the array bit lines. For each array bit line there is at least one connection terminal per bank in the plurality of banks for which the array bit line will be used. A plurality of bank select transistors is provided to act as bank select circuitry. The bank select transistors are operable to selectively connect respective bank bit lines to corresponding connection terminals for array bit lines. The bank select transistors are characterized by allowing independent connection of bank bit lines to sense lines of the plurality of array bit lines, while minimizing the number of transistors in the sensing path. In embodiments described, the bank select transistors allow independent connection of the bank bit lines to both sense lines and ground lines in the plurality of array bit lines.