Patents Assigned to Oki Semiconductor
  • Patent number: 6377085
    Abstract: A precision bias is provided for a differential transconductor. The precision bias includes a bias circuit, a differential amplifier and a current mirror. The current mirror includes at least two mirror transistors, one of which is connected to the bias circuit, and th other of which is connected to the differential amplifier. The bias circuit provides a bias current, which the current mirror accurately reflects to the differential amplifier as a tail current. By providing identical operating conditions to the bias circuit and first mirror transistor as are seen at the differential amplifier and second mirror transistor, the precision bias can more accurately reflect the bias current into the tail current. This can reduce the DC output currents of the differential amplifier to substantially zero, which improves its performance. A second bias circuit provides the gate-source voltage of the two transistors forming the load of the differential transconductor.
    Type: Grant
    Filed: November 6, 2000
    Date of Patent: April 23, 2002
    Assignee: Oki Semiconductor
    Inventor: Horia Giuroiu
  • Patent number: 6344769
    Abstract: A switched current source is provided for differentially switching high currents onto different loads at high speed and with a high degree of accuracy. The switched current source includes a differential amplifier, which receives an input current and selectively provides first and second output currents, a voltage amplifier, and a capacitor, which compensates the frequency response of certain feedback amplifiers and stores the potential of a certain node during transients. The differential amplifier includes two transistors each connected to the input current and for providing one of the output currents when activated. The first and second transistors are controlled by first through fourth switches. The first switch and the second switches turn on the first and second transistors, respectively, when closed. The third and the fourth switches pull down the first and second transistors, respectively, when closed.
    Type: Grant
    Filed: October 13, 2000
    Date of Patent: February 5, 2002
    Assignee: Oki Semiconductor
    Inventor: Horia Giuroiu
  • Patent number: 6215701
    Abstract: A nonvolatile memory cell includes first and second MOS transistors, such as a PMOS transistor and NMOS transistor in a CMOS cell. One of the two transistors provides a floating gate for storing data while the other transistor is provided with a control gate for selecting the memory cell, and is connected with a bit line for reading data stored in the cell. The nonvolatile memory cell may be integrated into a logic device, such as a CMOS gate array, using PMOS and NMOS transistor cells formed in the gate array. In that case, the nonvolatile memory cell may be fabricated in a logic device with the standard processes used to produce the logic device.
    Type: Grant
    Filed: December 22, 1998
    Date of Patent: April 10, 2001
    Assignee: OKI Semiconductor
    Inventors: Chingchi Yao, Chung-Jen Chien
  • Patent number: 6201725
    Abstract: A nonvolatile memory cell includes first and second MOS transistors, such as a PMOS transistor and NMOS transistor in a CMOS cell. One of the two transistors provides a floating gate for storing data while the other transistor is provided with a control gate for selecting the memory cell, and is connected with a bit line for reading data stored in the cell. The nonvolatile memory cell may be integrated into a logic device, such as a CMOS gate array, using PMOS and NMOS transistor cells formed in the gate array. In that case, the nonvolatile memory cell may be fabricated in a logic device with the standard processes used to produce the logic device.
    Type: Grant
    Filed: June 12, 2000
    Date of Patent: March 13, 2001
    Assignee: Oki Semiconductor
    Inventors: Chingchi Yao, Chung-Jen Chien
  • Patent number: 6097048
    Abstract: A dynamic random access memory (DRAM) cell includes first and second MOS transistors, such as a PMOS transistor and NMOS transistor in a CMOS cell. One of the two transistors functions as a switch transistor while the other transistor is configured as a storage capacitor. The DRAM cell may be integrated into a logic device, such as a CMOS gate array, using PMOS and NMOS transistor cells formed in the gate array. In that case, the DRAM cell may be fabricated in a logic device with the standard processes used to produce the logic device.
    Type: Grant
    Filed: December 22, 1998
    Date of Patent: August 1, 2000
    Assignee: Oki Semiconductor
    Inventors: Chingchi Yao, Chung-Jen Chien, Thomas Chao