Multiply-accumulate circuits

A method comprising:

• driving, by a row driver of a multiply-accumulate circuit, a row value onto a row value line based on an input vector bit of an input vector received by the row driver, the row driver comprising a shift register that is initialized to a ‘0’ value, and the driving by the row driver being response to the shift register storing a ‘1’ value propagated by a token propagation unit;
• driving, by the row driver, a row line that controls a corresponding memristor according to the input vector bit, the corresponding memristor storing a weight value bit of a weight value to apply to the input vector for a multiply-accumulate operation;
• generating, by a sense amplifier, an output voltage based on a current output from the corresponding memristor;
• and
• adjusting, by counter circuitry, a counter value that represents a running total of the multiply-accumulate operation based on the row value line, the output voltage generated by the sense amplifier, or a combination of both.

A multiply-accumulate circuit comprising:

• a set of row driver circuits, each row driver of the row driver circuits comprising a shift register that is initialized to a ‘0’ value, wherein each row driver receives an input vector bit of an input vector;
• a token propagation unit configured to propagate a ‘1’ value through the set of row driver circuits, wherein a particular row is activated when the shift register of the row driver of the particular row stores a ‘1’ value propagated by the token propagation unit;
• a first circuitry column comprising:
• a first set of memristor circuits linked to the set of row driver circuits, the first set of memristor circuits programmed with a first weight value;
• a sense amplifier linked to the first set of memristor circuits to apply an output voltage based on a current output from a memristor of the first set of memristor circuits, the current output representative of a weight value bit stored by the memristor;
• and
• counter circuitry to store a first counter value and to adjust the first counter value based on a row value output from the set of row driver circuits, the output voltage of the sense amplifier of the first circuitry column, or both;
• and
• a column circuitry column comprising:
• a second set of memristor circuits also linked to the set of row driver circuits, the second set of memristor circuits programmed with a second weight value different from the first weight value;
• a sense amplifier linked to the second set of memristor circuits to apply an output voltage based on a current output from a memristor of the second set of memristor circuits, the current output representative of a weight value bit stored by the memristor;
• and
• counter circuitry to store a second counter value and to adjust the second counter value based on a row value output from the set of row driver circuits, the output voltage of the sense amplifier of the second circuitry column, or both.