Local Reference Voltage Generator for Non-Volatile Memory

A system comprising:

• an array of non-volatile memory (NVM) cells divided into a plurality of blocks;
• a sensing circuit coupled to the array to receive memory signals therefrom and to compare the memory signals to reference voltages to read data from the NVM cells;
• and
• a reference voltage generator coupled to the sensing circuit to provide reference voltages thereto, the reference voltage generator configured to provide one of a number of reference voltages to the sensing circuit based on which one of the plurality of blocks is being read.

A method of operating a memory device comprising:

• logically divide an array of memory cells in the memory device into a plurality of blocks based on row and column addresses of cells in each block;
• performing a number of margin sweeps for each block and determining a local reference voltage for each block;
• determining from the local reference voltages for each block a base reference voltage for the array and an adjustment reference voltage for each block;
• storing the adjustment reference voltage for each block in a lookup table;
• during a read operation of one of the plurality of blocks generating the local reference voltage previously determined for the block being read by looking up and generating the adjustment reference voltage for the block, and combining it with the base reference voltage;
• and
• applying the local reference voltage to a reference bitline of a sense-amplifier coupled to a bitline of the memory cells being read.