Patents by Inventor Leo B. Freeman

Leo B. Freeman has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 4677312
    Abstract: It is well known that the base width of a transistor has a direct bearing on transistor speed and the punch-through voltage. A solution to the transistor speed versus break down (punch through) voltage problem is disclosed. Output transistors are serially connected between power supply rails along with associated transistor base driving circuitry. The circuit arrangement ensures that the supply voltage divides between the series connected output transistors and prevents excessive voltage from being applied to each output transistor.
    Type: Grant
    Filed: April 25, 1986
    Date of Patent: June 30, 1987
    Assignee: International Business Machines Corporation
    Inventor: Leo B. Freeman
  • Patent number: 4490630
    Abstract: Disclosed is a high performance current switch push-pull driver circuit. A first output of the current switch is direct coupled to the push-pull driver while the second output of the current switch is coupled to the push-pull driver by means of an emitter follower and current mirror. Emitter followers connected to the current switch provide a first pair of true/complement outputs while push-pull drivers provide a second set of true/complementary outputs having a higher drive capability. The current mirror is biased near its turn on potential providing current control switching of the current mode transistor and the push-pull driver transistor with which it is coupled. The circuit is greatly tolerant for varying load conditions, is protected against short circuit and power supply failures and has means for three state operation.
    Type: Grant
    Filed: June 30, 1982
    Date of Patent: December 25, 1984
    Assignee: International Business Machines Corporation
    Inventor: Leo B. Freeman
  • Patent number: 3970950
    Abstract: A dual channel high gain differential amplifier utilizing enhancement depletion MOS field effect transistors which exhibits high common mode rejection and fast switching characteristics.
    Type: Grant
    Filed: March 21, 1975
    Date of Patent: July 20, 1976
    Assignee: International Business Machines Corporation
    Inventors: Leo B. Freeman, Jr., Robert J. Incerto, Joseph A. Petrosky, Jr.
  • Patent number: 3961355
    Abstract: A semiconductor device has a heavily doped semiconductor substrate with a lightly doped epitaxial layer overlying a surface of the substrate and of the same conductivity type as the substrate. Electrically insulating barriers extend from at least the surface of the epitaxial layer into the substrate so as to electrically isolate non-common areas of each surface leakage sensitive device within the epitaxial layer from the non-common areas of adjacent surface leakage sensitive devices.
    Type: Grant
    Filed: November 18, 1974
    Date of Patent: June 1, 1976
    Assignee: International Business Machines Corporation
    Inventors: Shakir A. Abbas, Chi S. Chang, Leo B. Freeman, Jr., Ronald W. Knepper