US Patent 7920423 Non volatile memory circuit with tailored reliability

A non-volatile memory (NVM) circuit is provided, that includes at least a first and second NVM sub-array. The first sub-array is built from first memory cells. The second NVM sub-array is built from second memory cells that are constructed differently from the first memory cells. The NVM sub-arrays share a support circuit. In some embodiments the sub-arrays can be constructed, so that they exhibit different characteristics tailored to their intended use. For example one sub-array might be tailored for data retention, while the next sub-array for programming endurance, still another for write disturb immunity.