Methods and circuitry for programming non-volatile resistive switches using varistors

A method for operating an integrated circuit that includes a programmable resistive switch having a first non-volatile resistive memory element, a second non-volatile resistive memory element, a first varistor, and a second varistor, the method comprising:

• using the first varistor to program the first non-volatile resistor memory element;
• using the second varistor to program the second non-volatile resistor memory element;
• and
• using driver circuits to apply programming voltages onto the first and second varistors while gate-to-source and gate-to-drain junctions of transistors within the driver circuits are kept below a target voltage level that meets transistor reliability criteria.

An integrated circuit, comprising:

• an array of resistive switches, wherein each resistive switch in the array comprises a top non-volatile resistive memory element, a bottom non-volatile resistive memory element coupled in series with the top non-volatile resistive memory element, a first varistor operable to program the top non-volatile resistive memory element, and a second varistor operable to program the bottom non-volatile resistive memory element;
• a write row driver coupled to the first varistor in each resistive switch formed along a given row in the array;
• a read row driver coupled to an anode of the bottom non-volatile resistive memory element in each resistive switch formed along the given row in the array;
• a write column driver coupled to the second varistor in each resistive switch formed along a given column in the array;
• and
• a read column driver coupled to an anode of the top non-volatile resistive memory element in each resistive switch formed along the given column in the array.