Patents by Inventor Tsai-Fu Chang

Tsai-Fu Chang 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: 8169206
    Abstract: The duty of a PWM signal in a power converter is extracted to feed forward to modulate the slope of a linear oscillating ramp signal or the voltage level of an error signal, so as to modulate the duty of the PWM signal, by which the transient response of the power converter and the stability of the PWM loop both are improved.
    Type: Grant
    Filed: December 6, 2010
    Date of Patent: May 1, 2012
    Assignee: Richtek Technology Corp.
    Inventors: Tsai-Fu Chang, Liang-Pin Tai
  • Patent number: 8040122
    Abstract: The duty of a PWM signal in a power converter is extracted to feed forward to modulate the slope of a linear oscillating ramp signal or the voltage level of an error signal, so as to modulate the duty of the PWM signal, by which the transient response of the power converter and the stability of the PWM loop both are improved.
    Type: Grant
    Filed: September 4, 2007
    Date of Patent: October 18, 2011
    Assignee: Richtek Technology Corp.
    Inventors: Tsai-Fu Chang, Liang-Pin Tai
  • Publication number: 20110068763
    Abstract: The duty of a PWM signal in a power converter is extracted to feed forward to modulate the slope of a linear oscillating ramp signal or the voltage level of an error signal, so as to modulate the duty of the PWM signal, by which the transient response of the power converter and the stability of the PWM loop both are improved.
    Type: Application
    Filed: December 6, 2010
    Publication date: March 24, 2011
    Applicant: RICHTEK TECHNOLOGY CORP.
    Inventors: TSAI-FU CHANG, LIANG-PIN TAI
  • Patent number: 7498792
    Abstract: A pulse-width-modulation (PWM) control system with nonlinear ramp is disclosed. A nonlinear ramp generator generates a nonlinear ramp varied with the duty (Vout/Vin) in a waveform signal, which could be a logarithm ramp, an exponent ramp, a multi-piecewise-linear ramp, a power ramp or a combination of above. The slope of the ramp is not a constant due to the non-linear characteristic. The voltage Vramp will vary with the input voltage Vin, output voltage Vout, and duty (Vout/Vin), therefore it will reduce the influence of the input voltage Vin or output voltage Vout on the modulation gain and loop gain, even to keep the modulation gain and loop gain in constant value. As mentioned-above, the present invention improves the transient response of system, the sensitivity for variation of Vin and Vout, thus it is capable of correcting the output voltage quickly, for supplying a more steady power output.
    Type: Grant
    Filed: November 9, 2005
    Date of Patent: March 3, 2009
    Assignee: Richtek Technology Coporation
    Inventors: Tsai-Fu Chang, Liang-Pin Tai
  • Publication number: 20080062731
    Abstract: The duty of a PWM signal in a power converter is extracted to feed forward to modulate the slope of a linear oscillating ramp signal or the voltage level of an error signal, so as to modulate the duty of the PWM signal, by which the transient response of the power converter and the stability of the PWM loop both are improved.
    Type: Application
    Filed: September 4, 2007
    Publication date: March 13, 2008
    Applicant: RICHTEK TECHNOLOGY CORP.
    Inventors: TSAI-FU CHANG, LIANG-PIN TAI
  • Publication number: 20060273769
    Abstract: A pulse-width-modulation (PWM) control system with nonlinear ramp is disclosed. A nonlinear ramp generator generates a nonlinear ramp varied with the duty (Vout/Vin) in a waveform signal, which could be a logarithm ramp, an exponent ramp, a multi-piecewise-linear ramp, a power ramp or a combination of above. The slope of the ramp is not a constant due to the non-linear characteristic. The voltage Vramp will vary with the input voltage Vin, output voltage Vout, and duty (Vout/Vin), therefore it will reduce the influence of the input voltage Vin or output voltage Vout on the modulation gain and loop gain, even to keep the modulation gain and loop gain in constant value. As mentioned-above, the present invention improves the transient response of system, the sensitivity for variation of Vin and Vout, thus it is capable of correcting the output voltage quickly, for supplying a more steady power output.
    Type: Application
    Filed: November 9, 2005
    Publication date: December 7, 2006
    Inventors: Tsai-Fu Chang, Liang-Pin Tai
  • Patent number: 6723649
    Abstract: A method of fabricating a semiconductor memory device, particularly a mask ROM. A sacrificial oxide layer is formed on a silicon substrate and then a photoresist layer is formed on the sacrificial oxide layer. The photoresist layer is patterned to form a plurality of openings where bit lines are to extend respectively. Taking the patterned photoresist layer as a mask, arsenic ions are implanted into the silicon substrate through the openings and then boron ions are implanted into the silicon substrate through the openings. The implantation depth of boron ions are deeper than arsenic ions. The photoresist layer and the sacrificial oxide layer are removed after implantation. A gate oxide and a field oxide are grown simultaneously on the non-implanted and the implanted regions of the semiconductor layers respectively and a gate conductive layer is deposited on the silicon substrate.
    Type: Grant
    Filed: May 31, 2002
    Date of Patent: April 20, 2004
    Assignee: Macronix International Co.
    Inventors: Tsai-Fu Chang, Shih-Lin Chu, Ching-Pen Yeh
  • Publication number: 20040056317
    Abstract: A semiconductor device having a memory array that includes a plurality of substantially parallel word lines, a plurality of substantially parallel bit lines, wherein each of the plurality of the word lines is substantially perpendicular to each of the plurality of the bit lines, a first dummy word line disposed at a periphery of the memory array, wherein the first dummy word line is substantially parallel to the plurality of word lines and overlaps at least two non-adjacent bit lines.
    Type: Application
    Filed: September 30, 2003
    Publication date: March 25, 2004
    Applicant: Macronix International Co., Ltd.,
    Inventors: Tsai-Fu Chang, Shih Lin Chu, Ching Pen Yeh
  • Patent number: 6677199
    Abstract: A semiconductor device having a memory array that includes a plurality of substantially parallel word lines, a plurality of substantially parallel bit lines, wherein each of the plurality of the word lines is substantially perpendicular to each of the plurality of the bit lines, a first dummy word line disposed at a periphery of the memory array, wherein the first dummy word line is substantially parallel to the plurality of word lines and overlaps at least two non-adjacent bit lines.
    Type: Grant
    Filed: July 2, 2002
    Date of Patent: January 13, 2004
    Assignee: Macronix International Co., Ltd.
    Inventors: Tsai-Fu Chang, Shih Lin Chu, Ching Pen Yeh
  • Publication number: 20040005758
    Abstract: A semiconductor device having a memory array that includes a plurality of substantially parallel word lines, a plurality of substantially parallel bit lines, wherein each of the plurality of the word lines is substantially perpendicular to each of the plurality of the bit lines, a first dummy word line disposed at a periphery of the memory array, wherein the first dummy word line is substantially parallel to the plurality of word lines and overlaps at least two non-adjacent bit lines.
    Type: Application
    Filed: July 2, 2002
    Publication date: January 8, 2004
    Applicant: Macronix International Co., Ltd.
    Inventors: Tsai-Fu Chang, Shih Lin Chu, Ching Pen Yeh
  • Publication number: 20030141278
    Abstract: A method of fabricating a semiconductor memory device, particularly a mask ROM. A sacrificial oxide layer is formed on a silicon substrate and then a photoresist layer is formed on the sacrificial oxide layer. The photoresist layer is patterned to form a plurality of openings where bit lines are to extend respectively. Taking the patterned photoresist layer as a mask, arsenic ions are implanted into the silicon substrate through the openings and then boron ions are implanted into the silicon substrate through the openings. The implantation depth of boron ions are deeper than arsenic ions. The photoresist layer and the sacrificial oxide layer are removed after implantation. A gate oxide and a field oxide are grown simultaneously on the non-implanted and the implanted regions of the semiconductor layers respectively and a gate conductive layer is deposited on the silicon substrate.
    Type: Application
    Filed: May 31, 2002
    Publication date: July 31, 2003
    Inventors: Tsai-Fu Chang, Shih-Lin Chu, Ching-Pen Yeh