Data processing system and method for generating a digital code with a physically unclonable function

In a memory array comprising a plurality of memory cells organized as intersecting rows and columns, a row comprising a word line and all the memory cells coupled to the word line, and a column comprising a bit line pair and all the memory cells coupled to the bit line pair, a method for generating a digital code, the method comprising:

• writing a same predetermined logic state to all the plurality of memory cells;
• activating a plurality of word lines in the memory array at the same time to couple multiple memory cells to a bit line of the bit line pair, wherein the bit line pair includes a true bit line and a complement bit line;
• coupling a first bit line of the memory array to a first input of a comparator;
• coupling a second bit line of the memory array to a second input of the comparator, wherein the second bit line is from a different column than the first bit line;
• coupling a third bit line to the first bit line and coupling a fourth bit line to the second bit line of the one logic bit, wherein each of the first, second, third, and fourth bit lines are all either one of a true bit line or a complement bit line;
• generating a current on each of the first, second, third, and fourth bit lines, wherein the current on each of the first, second, third, and fourth bit lines is provided by the multiple memory cells coupled to each of the first, second, third, and fourth bit lines at the same time during the read operation;
• converting the currents on the first, second, third, and fourth bit lines to voltages;
• using the comparator, comparing the voltage on the first bit line and third bit line to the voltage on the second bit line and fourth bit line;
• and
• outputting the one logic bit from the comparator as part of the digital code, a logic state of the one logic bit determined in response to the comparison of the voltage on the first bit line and third bit line to the voltage on the second bit line and fourth bit line.

A data processing system comprising:

• a processor;
• a memory array coupled to the processor, the memory array including a plurality of memory cells, a plurality of word lines, and a plurality of bit line pairs intersecting the plurality of word lines, wherein a memory cell of the plurality of memory cells is located at each intersection of the plurality of word lines and the plurality of bit line pairs, and wherein each of the plurality of bit line pairs includes a true bit line and a complement bit line;
• a word line driver multiplexer coupled to the plurality of word lines, the word line driver multiplexer selecting at least two word lines at the same time to couple multiple memory cells to a bit line for a read operation of one bit in response to a row address;
• a bit line selection circuit coupled to the plurality of bit line pairs, the bit line selection circuit for selecting a first bit line of a first bit line pair and a second bit line of a second bit line pair in response to a column address, wherein the second bit line is coupled to different memory cells than the first bit line, wherein the bit line selection circuit further comprises a mode for coupling a third bit line of a third bit line pair to the first bit line and coupling a fourth bit line of a fourth bit line pair to the second bit line at the same time during the read operation of the one bit, wherein a signal generated on each of the first, second, third, and fourth bit lines is provided by multiple memory cells coupled to each of the first, second, third, and fourth bit lines in response to the at least two word lines being selected at the same time, and wherein each of the first, second, third, and fourth bit lines are all either one of a true bit line or a complement bit line;
• and
• a comparator for comparing a difference between the signal generated on the first and third bit lines to the signal generated on the second and fourth bit lines, and the comparator for outputting the bit having a logic state representative of the difference.