Patents by Inventor Lejan Pu

Lejan Pu 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: 11705891
    Abstract: Embodiments of the present disclosure provide a level shifter, including: first and second NMOS transistors, wherein the sources of the first and second NMOS transistors are coupled to a first voltage, the gate of the first NMOS transistor is connected to an inverse of an input signal that varies between a second voltage and a third voltage, and wherein the gate of the second NMOS transistor receives a buffer of the input signal. a breakdown protection circuit has third and fourth NMOS transistors, the gates of the third and fourth NMOS transistors being connected to the third voltage, the drain of the first NMOS transistor being connected to the source of the third NMOS transistor, and the drain of the second NMOS transistor being connected to the source of the fourth NMOS transistor. A pull-up circuit is connected to the drains of the third and fourth NMOS transistors.
    Type: Grant
    Filed: May 17, 2022
    Date of Patent: July 18, 2023
    Assignee: GLOBALFOUNDRIES U.S. Inc.
    Inventors: Siva Kumar Chinthu, Devesh Dwivedi, Sundar Veerendranath Palle, Lejan Pu
  • Patent number: 10706905
    Abstract: The present disclosure generally relates to semiconductor structures and, more particularly, to a single path memory sense amplifier circuit and methods of manufacture. The circuit includes a sense amplifier circuit comprising a plurality of self-aligned transistors in a single sensing path; and a memory array connected to the sense amplifier circuit by the single sensing path.
    Type: Grant
    Filed: December 28, 2018
    Date of Patent: July 7, 2020
    Assignee: GLOBALFOUNDRIES INC.
    Inventors: Yentsai Huang, Chunsung Chiang, Wuyang Hao, Jack T. Wong, Lejan Pu
  • Publication number: 20200211610
    Abstract: The present disclosure generally relates to semiconductor structures and, more particularly, to a single path memory sense amplifier circuit and methods of manufacture. The circuit includes a sense amplifier circuit comprising a plurality of self-aligned transistors in a single sensing path; and a memory array connected to the sense amplifier circuit by the single sensing path.
    Type: Application
    Filed: December 28, 2018
    Publication date: July 2, 2020
    Inventors: Yentsai Huang, Chunsung Chiang, Wuyang Hao, Jack T. Wong, Lejan Pu
  • Patent number: 8693273
    Abstract: A sense amplifier comprising a reference current developed from a programmed and a non-programmed reference cell is used to read a signal from a magnetic random access memory (MRAM) comprising magnetic tunnel junction (MTJ) cells. The average current is determined from reference cells in as few as one sense amplifier and as many as n sense amplifiers, and is an average current between the programmed reference cell and the non-programmed reference cell that approximates the mid point between the two states. The sense amplifier can be fully differential or a non differential sense amplifier.
    Type: Grant
    Filed: January 6, 2012
    Date of Patent: April 8, 2014
    Assignee: Headway Technologies, Inc.
    Inventors: Perng-Fei Yuh, Po-Kang Wang, Lejan Pu
  • Patent number: 8605520
    Abstract: Systems and methods to improve reliability of sensing operations of semiconductor memory arrays requiring reading references such as MRAM or any type of phase change memory (PCM), and to improve yield of the memory arrays have been achieved. The memory array is divided into multiple parts, such as sections or segments. Reference word lines or reference bit lines or both are deployed in each of the multiple parts. Thus, the distance between an accessed line and the correspondent reference line is reduced, and hence the parasitic parameter tracking capability is enhanced significantly. Additionally spare reference word lines or spare reference bit lines can be deployed in each of the multiple parts.
    Type: Grant
    Filed: September 22, 2010
    Date of Patent: December 10, 2013
    Assignee: MagIC Technologies, Inc.
    Inventors: Lejan Pu, Toshio Sunaga
  • Patent number: 8488357
    Abstract: Systems and methods for realizing reference currents to improve reliability of sensing operations of segmented semiconductor memory arrays have been achieved. Preferred embodiments of the invention comprise MRAM arrays but the invention could be applied to any other memories requiring access on small, segmented arrays. All embodiments of the invention comprise a folded bit lines scheme, either in adjacent bit lines or in segment-to-segment folded bit lines. In two embodiments alternate strapping of Poly-Si Word Lines in every second segment is achieved by metal layer of Read Word Line and Write Select Line. An embodiment has stored 1 and 0 cells on both sides of a selected segment to be read.
    Type: Grant
    Filed: October 22, 2010
    Date of Patent: July 16, 2013
    Assignee: MagIC Technologies, Inc.
    Inventors: Toshio Sunaga, Lejan Pu, Perng-Fei Yuh, Chao-Hung Chang
  • Publication number: 20130176773
    Abstract: A sense amplifier comprising a reference current developed from a programmed and a non-programmed reference cell is used to read a signal from a magnetic random access memory (MRAM) comprising magnetic tunnel junction (MTJ) cells. The average current is determined from reference cells in as few as one sense amplifier and as many as n sense amplifiers, and is an average current between the programmed reference cell and the non-programmed reference cell that approximates the mid point between the two states. The sense amplifier can be fully differential or a non differential sense amplifier.
    Type: Application
    Filed: January 6, 2012
    Publication date: July 11, 2013
    Applicant: HEADWAY TECHNOLOGIES, INC.
    Inventors: Perng-Fei Yuh, Pokang Wang, Lejan Pu
  • Patent number: 8217684
    Abstract: Systems and methods for realizing current drivers without current or voltage feedback for devices that require accurate current drive with zero standby current has been disclosed. In a preferred embodiment of the invention this current driver is applied for write circuits for MRAMs. A fast and accurate reference current is generated by diode voltage divided by resistor without any feedback. The diode current is not fed back from the reference current. The diode current is generated from a regulated voltage. Temperature compensation of the write current is inherently built in the diode current reference. Fine-tuning of the temperature coefficient is achieved by mixing poly and diffusion resistors. A switch inserted in the current driver can turn on the driver fast and without a need for standby current. Leading boost in the current driver can fast charge the large coupling capacitance of word and bit lines and speed up write timing.
    Type: Grant
    Filed: October 12, 2010
    Date of Patent: July 10, 2012
    Assignee: MagIC Technologies, Inc.
    Inventors: Perng-Fei Yuh, Pokang Wang, Lejan Pu, Minh Tran, Chao-Hung Chang
  • Publication number: 20120099358
    Abstract: Systems and methods for realizing reference currents to improve reliability of sensing operations of segmented semiconductor memory arrays have been achieved. Preferred embodiments of the invention comprise MRAM arrays but the invention could be applied to any other memories requiring access on small, segmented arrays. All embodiments of the invention comprise a folded bit lines scheme, either in adjacent bit lines or in segment-to-segment folded bit lines. In two embodiments alternate strapping of Poly-Si Word Lines in every second segment is achieved by metal layer of Read Word Line and Write Select Line. An embodiment has stored 1 and 0 cells on both sides of a selected segment to be read.
    Type: Application
    Filed: October 22, 2010
    Publication date: April 26, 2012
    Inventors: Toshio Sunaga, Lejan Pu, Perng-Fei Yuh, Chao-Hung Chang
  • Publication number: 20120086476
    Abstract: Systems and methods for realizing current drivers without current or voltage feedback for devices that require accurate current drive with zero standby current has been disclosed. In a preferred embodiment of the invention this current driver is applied for write circuits for MRAMs. A fast and accurate reference current is generated by diode voltage divided by resistor without any feedback. The diode current is not fed back from the reference current. The diode current is generated from a regulated voltage. Temperature compensation of the write current is inherently built in the diode current reference. Fine-tuning of the temperature coefficient is achieved by mixing poly and diffusion resistors. A switch inserted in the current driver can turn on the driver fast and without a need for standby current. Leading boost in the current driver can fast charge the large coupling capacitance of word and bit lines and speed up write timing.
    Type: Application
    Filed: October 12, 2010
    Publication date: April 12, 2012
    Inventors: Perng-Fei Yuh, Pokang Wang, Lejan Pu, Minh Tran, Chao-Hung Chang
  • Publication number: 20120069644
    Abstract: Systems and methods to improve reliability of sensing operations of semiconductor memory arrays requiring reading references such as MRAM or any type of phase change memory (PCM), and to improve yield of the memory arrays have been achieved. The memory array is divided into multiple parts, such as sections or segments. Reference word lines or reference bit lines or both are deployed in each of the multiple parts. Thus, the distance between an accessed line and the correspondent reference line is reduced, and hence the parasitic parameter tracking capability is enhanced significantly. Additionally spare reference word lines or spare reference bit lines can be deployed in each of the multiple parts.
    Type: Application
    Filed: September 22, 2010
    Publication date: March 22, 2012
    Inventors: Lejan Pu, Toshio Sunaga
  • Patent number: 7609543
    Abstract: Voltage and current stress for magnetic random access memory (MRAM) cells can weed out potential early failure cells. Method and circuit implementation of such a stress test for a MRAM comprise coupling a stress test circuit to the read bus of the MRAM and stressing the Magnetic Tunnel Junctions (MTJS) by tying them to ground by activating isolation transistors associated with them. Read word lines control which MTJs are stressed Both the method and implementation can be used for any memory cells based on resistance differences, such as Phase RAM or Spin Valve MRAM.
    Type: Grant
    Filed: September 27, 2007
    Date of Patent: October 27, 2009
    Assignee: MagIC Technologies, Inc.
    Inventors: Hsu Kai Yang, Lejan Pu, Perng-Fei Yuh, Po-Kang Wang
  • Publication number: 20090086531
    Abstract: Voltage and current stress for magnetic random access memory (MRAM) cells can weed out potential early failure cells. Method and circuit implementation of such a stress test for a MRAM comprise coupling a stress test circuit to the read bus of the MRAM and stressing the Magnetic Tunnel Junctions (MTJS) by tying them to ground by activating isolation transistors associated with them. Read word lines control which MTJs are stressed Both the method and implementation can be used for any memory cells based on resistance differences, such as Phase RAM or Spin Valve MRAM.
    Type: Application
    Filed: September 27, 2007
    Publication date: April 2, 2009
    Inventors: Hsu Kai Yang, Lejan Pu, Perng-Fei Yuh, Po-Kang Wang