Patents by Inventor Seeteck Tan
Seeteck Tan 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).
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Publication number: 20100259332Abstract: A circuit can be used to a control the voltage of a voltage controlled oscillator (VCO) can include a first comparator, a second comparator, an accumulator, and an output device. The first comparator outputs a first pulse signal when the control voltage is higher than a high threshold voltage. The second comparator outputs a second pulse signal when the control voltage is lower than a low threshold voltage. The accumulator increases the value of a switch control signal if the first pulse signal is received or decreases the value of the switch control signal if the second pulse signal is received. The output device generates a compensation voltage to compensate the control voltage of the VCO depending on the value of the switch control signal.Type: ApplicationFiled: April 10, 2009Publication date: October 14, 2010Inventor: Seeteck TAN
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Patent number: 7750693Abstract: A frequency divider is disclosed herein. The frequency divider includes a first latch circuit and a second latch circuit coupled to the first latch circuit. Each of the first latch circuit and the second latch circuit includes a first level for generating a source current, a second level for receiving a pair of input signals and for generating a pair of output signals, and a third level for receiving the source current and a pair of clock signals. The second level is coupled between the first level and the third level. The first level includes a first transistor having a source terminal and a substrate both coupled to a source voltage. The third level includes a plurality of transistors controlled by the pair of clock signals. Each transistor in the third level has a source terminal and a substrate both coupled to ground.Type: GrantFiled: June 5, 2008Date of Patent: July 6, 2010Assignee: O2Micro, Inc.Inventors: Meng Chu, Seeteck Tan
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Patent number: 7643805Abstract: A variable gain amplifier (VGA) circuit and an automatic gain control (AGC) method thereof are disclosed. The VGA circuit includes an amplifier circuit and an AGC circuit. The amplifier circuit amplifies an input signal to an output signal according to a predetermined gain and the AGC circuit is connected to the amplifier circuit for regulating the predetermined gain. The AGC circuit further includes a peak detector detecting a peak of the output signal, a replica of the peak detector for detecting a peak of a reference signal, and a comparator for comparing the peak of the output signal with the peak of the reference signal to provide a control signal and then providing the control signal to the amplifier circuit to regulate the predetermined gain.Type: GrantFiled: July 7, 2006Date of Patent: January 5, 2010Assignee: O2Micro International Ltd.Inventors: Seeteck Tan, Xiaoyong Luo
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Patent number: 7633347Abstract: An apparatus and method for operating a phase-locked loop circuit are disclosed. The phase locked loop circuit includes a plurality of resistive elements and a plurality of capacitive elements that are distributed in a charge pump, a loop filter and a voltage controlled oscillator. The plurality of resistive elements have a plurality of resistances that vary in proportion to each other. The plurality of capacitive elements have a plurality of capacitive elements that vary in proportion to each other. A damping factor of the phase-locked loop circuit is maintained substantially constant by the plurality of resistive elements and the plurality of capacitive elements.Type: GrantFiled: May 30, 2007Date of Patent: December 15, 2009Assignee: 02Micro International LimitedInventors: Seeteck Tan, Meng Chu
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Patent number: 7589657Abstract: An analog to digital converter (ADC) with interference rejection capability and method thereof are disclosed. The ADC includes a threshold generator, a comparator circuit, a counter and an integrator. By comparing a signal with positive and negative threshold signals from the threshold generator, the comparator circuit converts the signal from analog to digital based on the result of the comparison. The counter counts a percentage of the digital signal and generates a bit signal based on the counted percentage. In response to the bit signal, the integrator supplies a control signal to the threshold generator to regulate the positive and negative threshold signals so as to maintain the counted percentage at a predetermined percentage threshold.Type: GrantFiled: January 24, 2008Date of Patent: September 15, 2009Assignee: O2Micro International Ltd.Inventors: Seeteck Tan, Wenhuan Chen
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Publication number: 20080303561Abstract: A frequency divider is disclosed herein. The frequency divider includes a first latch circuit and a second latch circuit coupled to the first latch circuit. Each of the first latch circuit and the second latch circuit includes a first level for generating a source current, a second level for receiving a pair of input signals and for generating a pair of output signals, and a third level for receiving the source current and a pair of clock signals. The second level is coupled between the first level and the third level. The first level includes a first transistor having a source terminal and a substrate both coupled to a source voltage. The third level includes a plurality of transistors controlled by the pair of clock signals. Each transistor in the third level has a source terminal and a substrate both coupled to ground.Type: ApplicationFiled: June 5, 2008Publication date: December 11, 2008Inventors: Meng Chu, Seeteck Tan
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Patent number: 7463086Abstract: A tunable band pass filter is provided. The tunable band pass filter includes a band pass filter and a plurality of switches coupled to the band pass filter. The band pass filter includes a plurality of transconductors and a plurality of capacitors. The tunable band pass filter can be configured as a complex band pass filter or as a tuning device for tuning the center frequency of the complex band pass filter depending on the operation of the plurality of switches. The tuning device includes at least one tuning integrator and a comparator. The tuning integrator includes at least one transconductor and a capacitor. The transconductor is selected via the plurality of switches from the plurality of transconductors and the capacitor is selected via the plurality of switches from said plurality of capacitors. The selected transconductor and the selected capacitor determinines the center frequency of the band pass filter.Type: GrantFiled: November 17, 2006Date of Patent: December 9, 2008Assignee: O2Micro International Ltd.Inventors: Seeteck Tan, Meng Chu, Xiaozhe Chen
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Publication number: 20080218277Abstract: An apparatus and method for operating a phase-locked loop circuit are disclosed. The phase locked loop circuit includes a plurality of resistive elements and a plurality of capacitive elements that are distributed in a charge pump, a loop filter and a voltage controlled oscillator. The plurality of resistive elements have a plurality of resistances that vary in proportion to each other. The plurality of capacitive elements have a plurality of capacitive elements that vary in proportion to each other. A damping factor of the phase-locked loop circuit is maintained substantially constant by the plurality of resistive elements and the plurality of capacitive elements.Type: ApplicationFiled: May 30, 2007Publication date: September 11, 2008Inventors: Seeteck Tan, Meng Chu
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Patent number: 7411374Abstract: A capacitor charging circuit comprises, power transfer circuitry, power switching control circuitry and voltage measurement circuitry. The power transfer circuitry transfers power from a power source to a capacitor. The power switching control circuitry controls the switching that causes power to be delivered to the power transfer circuitry. The voltage measurement circuitry indirectly measures the output voltage to determine when to stop charging the capacitor.Type: GrantFiled: September 17, 2004Date of Patent: August 12, 2008Assignee: 02Micro Intermnational LimitedInventors: Seeteck Tan, Vlad Mihall Popescu-Stanesti
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Publication number: 20080139160Abstract: A tunable band pass filter is provided. The tunable band pass filter includes a band pass filter and a plurality of switches coupled to the band pass filter. The band pass filter includes a plurality of transconductors and a plurality of capacitors. The tunable band pass filter can be configured as a complex band pass filter or as a tuning device for tuning the center frequency of the complex band pass filter depending on the operation of the plurality of switches. The tuning device includes at least one tuning integrator and a comparator. The tuning integrator includes at least one transconductor and a capacitor. The transconductor is selected via the plurality of switches from the plurality of transconductors and the capacitor is selected via the plurality of switches from said plurality of capacitors. The selected transconductor and the selected capacitor determinines the center frequency of the band pass filter.Type: ApplicationFiled: November 17, 2006Publication date: June 12, 2008Inventors: Seeteck Tan, Meng Chu, Xiaozhe Chen
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Publication number: 20080122674Abstract: An analog to digital converter (ADC) with interference rejection capability and method thereof are disclosed. The ADC includes a threshold generator, a comparator circuit, a counter and an integrator. By comparing a signal with positive and negative threshold signals from the threshold generator, the comparator circuit converts the signal from analog to digital based on the result of the comparison. The counter counts a percentage of the digital signal and generates a bit signal based on the counted percentage. In response to the bit signal, the integrator supplies a control signal to the threshold generator to regulate the positive and negative threshold signals so as to maintain the counted percentage at a predetermined percentage threshold.Type: ApplicationFiled: January 24, 2008Publication date: May 29, 2008Inventors: Seeteck Tan, Wenhuan Chen
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Patent number: 7324037Abstract: An analog to digital converter (ADC) with interference rejection capability and method thereof are disclosed. The ADC includes a threshold generator, a comparator circuit, a counter and an integrator. By comparing a signal with positive and negative threshold signals from the threshold generator, the comparator circuit converts the signal from analog to digital based on the result of the comparison. The counter counts a percentage of the digital signal and generates a bit signal based on the counted percentage. In response to the bit signal, the integrator supplies a control signal to the threshold generator to regulate the positive and negative threshold signals so as to maintain the counted percentage at a predetermined percentage threshold.Type: GrantFiled: July 14, 2006Date of Patent: January 29, 2008Assignee: O2Micro International Ltd.Inventors: Seeteck Tan, Wenhuan Chen
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Publication number: 20080009255Abstract: A variable gain amplifier (VGA) circuit and an automatic gain control (AGC) method thereof are disclosed. The VGA circuit includes an amplifier circuit and an AGC circuit. The amplifier circuit amplifies an input signal to an output signal according to a predetermined gain and the AGC circuit is connected to the amplifier circuit for regulating the predetermined gain. The AGC circuit further includes a peak detector detecting a peak of the output signal, a replica of the peak detector for detecting a peak of a reference signal, and a comparator for comparing the peak of the output signal with the peak of the reference signal to provide a control signal and then providing the control signal to the amplifier circuit to regulate the predetermined gain.Type: ApplicationFiled: July 7, 2006Publication date: January 10, 2008Inventors: Seeteck Tan, Xiaoyong Luo
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Publication number: 20070237273Abstract: A complex filter with automatic tuning capabilities for filtering a complex signal is disclosed. The complex filter includes a first lowpass filter, a second lowpass filter, a plurality of resistors, an integrator, a comparator, and a digital unit. The complex filter includes an imaginary component and a real component. The integrator, the comparator and the digital unit forms a tuning circuit. The tuning circuit can generate a plurality of control signals to tune the complex filter to a predetermined frequency. The tuning circuit can be turned off after a predetermined period.Type: ApplicationFiled: May 17, 2006Publication date: October 11, 2007Inventors: Seeteck Tan, Du Dingkun, Li Yongming
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Publication number: 20050237032Abstract: A capacitor charging circuit comprises, power transfer circuitry, power switching control circuitry and voltage measurement circuitry. The power transfer circuitry transfers power from a power source to a capacitor. The power switching control circuitry controls the switching that causes power to be delivered to the power transfer circuitry. The voltage measurement circuitry indirectly measures the output voltage to determine when to stop charging the capacitor.Type: ApplicationFiled: September 17, 2004Publication date: October 27, 2005Inventors: Seeteck Tan, Vlad Popescu-Stanesti