A 16 x 16 nonvolatile programmable analog vector-matrix multiplier

In this paper, we present a 16 x 16 analog vectormatrix multiplier with analog electrically erasable and programmable read-only memories (EEPROM's) used as nonvolatile storage for the weight matrix values. Each weight matrix value is stored in an EEPROM transistor as a change of the threshold voltage, and the same EEPROM transistor is used for the multiplication by utilizing the square-law characteristic of the metal-oxide-semiconductor field-effect transistor. This allows a very simple circuit for the multiplier array with a size of about 1 x 1 mm2. The vector-matrix multiplier has been fabricated in a 1.5-mu m single-poly complementary metal-oxide-semiconductor/EEPROM technology and successfully tested