Voltage sensing type of matrix multiplication method for neuromorphic computing system

A device for generating sum-of-products, comprising:

• an array of variable resistance cells, variable resistance cells in the array each comprising a transistor and a programmable resistor connected in parallel, the array including n columns of cells including strings of series-connected cells and m rows of cells;
• m input drivers coupled to corresponding ones of the m rows of cells, the input drivers selectively applying inputs Xm to rows m;
• n column drivers applying currents In to corresponding ones of the n columns of cells;
• and
• voltage sensing circuits operatively coupled to the n columns of cells, wherein the array includes a first reference column of cells configured to generate a low column reference voltage and a second reference column of cells configured to generate a high column reference voltage;
• the device including:
• a circuit to generate sensing reference voltages as a function of the high and low column reference voltages;
• and
• wherein the voltage sensing circuits include comparators configured to compare voltages on selected columns of cells with the sensing reference voltages to generate outputs indicating voltage levels on the selected columns.

A method for operating an array of variable resistance cells, variable resistance cells in the array each comprising a transistor and a programmable resistor connected in parallel, the array including n columns of cells including strings of series-connected cells and m rows of cells, to produce sum-of-products data, comprising:

• programming the programmable resistors in the array with resistances corresponding to values of a weight factor Rmn for corresponding cells;
• selectively applying inputs Xm to more than one of the m rows in parallel;
• applying currents In to corresponding ones of the n columns of cells to produce a voltage representing a sum-of-products of the inputs Xm applied to the more than one of the m rows and the weight factors Rmn for the cells;
• and
• sensing voltages on one or more of then columns of cells to sense one or more of the voltages representing the sums of products.

A method for operating an array of variable resistance cells, variable resistance cells in the array each comprising a transistor and a programmed resistor connected in parallel, the array including n columns of cells including strings of series-connected cells and m rows of cells, to produce sum-of-products data, comprising:

• selectively applying inputs Xm to more than one of the m rows in parallel;
• applying currents In to corresponding ones of the n columns of cells to produce a voltage representing a sum-of-products of the inputs Xm applied to the more than one of the m rows and weight factors Rmn for the cells;
• and
• sensing voltages on one or more of then columns of cells to sense one or more of the voltages representing the sums of products.