Outer product engine with capacitive device array

A neural network circuit comprising:

• a crossbar array comprising a plurality of nodes;
• each node comprising a capacitive processing unit (CPU) including a capacitor device configured to store a charge representing a weight value associated with a neural network circuit operation, the capacitor device comprising:
• first conductive layer providing a first capacitor terminal and a second conductive layer providing a second capacitor terminal and an insulating dielectric material layer therebetween, said first conductive layer, second conductive layer and insulating dielectric material layer forming a stack;
• a floating gate semiconductor material layer disposed within the insulating material layer and configured for storing charge carriers;
• a first dielectric material layer formed along a sidewall of said stack and contacting a side edge of said floating gate semiconductor material layer;
• a second dielectric material layer formed along an opposing sidewall of said stack and contacting an opposite side edge of said floating gate semiconductor material layer;
• a first conductive electrode providing a third capacitor terminal separated from the side edge of the floating gate semiconductor material layer by the first dielectric material layer, and
• a second conductive electrode providing a fourth capacitor terminal separated from the opposite side edge of the floating gate semiconductor material layer by the second dielectric material layer;
• said capacitor device associated with a weight update circuit at a crossbar array node of a neural network circuit, a capacitance of said capacitor device taken across said first and second capacitor terminals representing a weight value used in a neural network circuit operation.

A method of operating a capacitor device in a neural network circuit, the method comprising:

• providing a capacitor device having a first metal or heavily doped semiconductor layer defining a first capacitor terminal and second metal or heavily doped semiconductor layer defining a second capacitor terminal and an insulating material layer therebetween, the capacitor device further comprising:
• a floating gate semiconductor material layer disposed within the insulating material layer and configured for storing charge carriers;
• a first low work function metal electrode defining a third capacitor terminal separated from a first side edge of the floating gate semiconductor material layer by a first dielectric material layer, and
• a second high work function metal electrode defining a fourth capacitor terminal separated from a second opposing side edge of the floating gate semiconductor material layer by a second dielectric material layer;
• said capacitor device associated with a weight update circuit at a crossbar array node of a neural network circuit, a capacitance of said capacitor device representing a weight value used in a neural network circuit operation;
• and
• programming the weight value of said weight update circuit for said neural network circuit operation by modifying a capacitance of the capacitor device associated with said weight update circuit using both the third and fourth capacitor terminals.