×

Non-volatile random access memory cell

  • US 4,703,456 A
  • Filed: 04/23/1986
  • Issued: 10/27/1987
  • Est. Priority Date: 04/24/1985
  • Status: Expired due to Fees
First Claim
Patent Images

1. A non-volatile random access memory cell comprising:

  • a volatile memory cell for storing a datum comprisingflip-flop circuit having a first and second nodes on which complementary signals corresponding to the stored datum are output, anda first capacitor connected to said first node; and

    a non-volatile memory cell comprisinga second capacitor, operatively connected to said second node, having a capacitance larger than that of said first capacitor,a memory transistor having a floating gate, connected between said second node and said second capacitor, said memory transistor acting as a switch in accordance with the polarity of the charge stored at said floating gate,a capacitor circuit comprising a tunnel capacitor operatively connected to said floating gate,means, operatively connected to said capacitor circuit, for applying a writing voltage having an amplitude large enough to cause a tunnel current to flow through said tunnel capacitor,a first transistor, operatively connected to said second node and to said capacitor circuit, for controlling the polarity of said tunnel current in accordance with said stored datum, said first transistor generating an output in response to one of said complementary signals at said second node, anda second transistor, operatively connected to said capacitor circuit receiving the output of said first transistor, for controlling the polarity of said tunnel current in accordance with said stored datum,said first and second transistors cooperatively controlling the polarity of the tunnel current to flow through said tunnel capacitor when said writing voltage is applied to said capacitor circuit, one of said first and second transistors being ON and the other being OFF when said tunnel current is to be flown, said polarity of the tunnel current being controlled to be in one of two directions opposite to each other depending on which one of said first and second transistors is ON, said two directions being such that said floating gate is provided with one of negative and positive charges by said tunnel current in one of said two directions, respectively.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×