Patents Represented by Law Firm Townsend and Townsend Khourie and Cres
  • Patent number: 5329487
    Abstract: A two-transistor flash EPROM cell includes a first floating gate transistor for programming the cell and a second merged transistor for reading the cell. The first transistor, a floating gate transistor, has a drain coupled to the write bit line, a gate coupled to the word line, and a source coupled to the source line. The merged transistor effectively consists of a floating gate transistor in series with a NMOS enhancement transistor. The series NMOS transistor has a voltage threshold of about 1 to 2 volts, thus preventing cell activation caused by overerasure (negative voltage threshold) of the floating gate transistor.
    Type: Grant
    Filed: March 8, 1993
    Date of Patent: July 12, 1994
    Assignee: Altera Corporation
    Inventors: Anil Gupta, Kuo-Lung Chen