Patents by Inventor Serban-Mihai Popescu

Serban-Mihai Popescu 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: 9083237
    Abstract: A converter circuit includes a converter and a controller. The converter converts an input voltage to an output voltage. The controller receives a reference voltage, generates a slew voltage having a substantially constant first slew rate if the reference voltage changes from a first level to a second level, and controls the converter based on the slew voltage to cause the output voltage to change from a third level to a fourth level at a substantially constant second slew rate.
    Type: Grant
    Filed: June 22, 2011
    Date of Patent: July 14, 2015
    Assignee: O2Micro, Inc.
    Inventors: Serban Mihai Popescu, Laszlo Lipcsei, Marius Padure, Guoyong Guo
  • Patent number: 8624567
    Abstract: A controller for a DC/DC converter includes multiple signal generators and a control circuit. The signal generators generate multiple pulse signals, each signal generator generating a corresponding pulse signal of the pulse signals and controlling the corresponding pulse signal to have a predetermined pulse width by counting a same preset number of cycles of a same oscillating signal. The control circuit selectively activates the signal generators according to an output of the DC/DC converter to generate the pulse signals.
    Type: Grant
    Filed: December 30, 2011
    Date of Patent: January 7, 2014
    Assignee: O2Micro, Inc.
    Inventor: Serban Mihai Popescu
  • Patent number: 8610412
    Abstract: A controller includes an input selector, multiple cores and a multiplexer. The multiplexer is operable for multiplexing control signals to multiple output channels to provide multiple output signals. Each output channel can output a respective output signal, and each output signal represents a cyclic rotation of the control signals. The input selector is operable for enabling the cores to operate in a standby state alternately to control a multiplexing sequence of the control signals.
    Type: Grant
    Filed: February 18, 2011
    Date of Patent: December 17, 2013
    Assignee: O2Micro Inc.
    Inventors: ChengHwa Teh, Laszlo Lipcsei, Serban Mihai Popescu
  • Patent number: 8587276
    Abstract: A controller for a power converter includes a first amplification stage and a second amplification stage coupled to the first amplification stage. The first amplification stage generates a first amplified signal at a first terminal of an energy storage element according to an output signal the power converter. The second amplification stage generates a second amplified signal at a second terminal of the energy storage element and varies the second amplified signal in response to a change in the output signal. The second amplification stage further decreases the variation of the second amplified signal based on the first amplified signal.
    Type: Grant
    Filed: May 2, 2011
    Date of Patent: November 19, 2013
    Assignee: O2Micro, Inc.
    Inventors: Laszlo Lipcsei, Serban Mihai Popescu, Vlad Mihail Dan Popescu-Stanesti
  • Patent number: 8487595
    Abstract: A circuit includes a first resistor, a second resistor, a voltage follower and a current mirror. The first resistor converts a current flowing through the first resistor to a voltage drop between positive and negative sides of the first resistor. The second resistor is coupled to the negative side of the first resistor. The voltage follower is coupled to the positive side of the first resistor via a non-inverting terminal, and coupled to the negative side of the first resistor through the second resistor via an inverting terminal to cause a voltage at the inverting terminal to follow a voltage at the non-inverting terminal. The current mirror is coupled to the voltage follower to provide a sensing current proportional to the current flowing through the first resistor.
    Type: Grant
    Filed: June 12, 2012
    Date of Patent: July 16, 2013
    Assignee: 02Micro Inc.
    Inventors: Serban Mihai Popescu, Christian Andreev
  • Publication number: 20130169254
    Abstract: A controller for a DC/DC converter includes multiple signal generators and a control circuit. The signal generators generate multiple pulse signals, each signal generator generating a corresponding pulse signal of the pulse signals and controlling the corresponding pulse signal to have a predetermined pulse width by counting a same preset number of cycles of a same oscillating signal. The control circuit selectively activates the signal generators according to an output of the DC/DC converter to generate the pulse signals.
    Type: Application
    Filed: December 30, 2011
    Publication date: July 4, 2013
    Inventor: Serban Mihai Popescu
  • Publication number: 20120249098
    Abstract: A circuit includes a first resistor, a second resistor, a voltage follower and a current mirror. The first resistor converts a current flowing through the first resistor to a voltage drop between positive and negative sides of the first resistor. The second resistor is coupled to the negative side of the first resistor. The voltage follower is coupled to the positive side of the first resistor via a non-inverting terminal, and coupled to the negative side of the first resistor through the second resistor via an inverting terminal to cause a voltage at the inverting terminal to follow a voltage at the non-inverting terminal. The current mirror is coupled to the voltage follower to provide a sensing current proportional to the current flowing through the first resistor.
    Type: Application
    Filed: June 12, 2012
    Publication date: October 4, 2012
    Applicant: O2Micro, Inc.
    Inventors: Serban Mihai POPESCU, Cristian ANDREEV
  • Publication number: 20120206120
    Abstract: A power regulator for converting an input voltage to an output voltage includes an error amplifier, a start-up circuit, and a pass device. The error amplifier is powered by the output voltage and provides a control current according to a difference between a reference signal and a feedback signal indicative of the output voltage. The start-up circuit is powered by the input voltage and provides a start-up current. The pass device receives the input voltage, provides the output voltage at an output terminal of the power regulator, generates an output current flowing through the output terminal according to the start-up current during a start-up duration of the power regulator, and generates the output current through the output terminal according to the control current during a normal operation of the power regulator.
    Type: Application
    Filed: February 13, 2012
    Publication date: August 16, 2012
    Applicant: O2MICRO, INC.
    Inventors: Laszlo Lipcsei, Serban Mihai Popescu
  • Patent number: 8232784
    Abstract: A current sensing circuit includes a first resistor, a second resistor and a sense amplifier. The first resistor converts a current flowing through the first resistor to a voltage drop between positive and negative sides of the first resistor. The second resistor is coupled to the negative side of the first resistor. The sense amplifier is coupled to the positive side of the first resistor via a first pin of the sense amplifier, and coupled to the negative side of the first resistor through the second resistor via a second pin of the sense amplifier. The sense amplifier employs a negative feedback to generate a sensing current proportional to the current flowing through the first resistor.
    Type: Grant
    Filed: March 18, 2009
    Date of Patent: July 31, 2012
    Assignee: O2Micro, Inc
    Inventors: Serban Mihai Popescu, Cristian Andreev
  • Patent number: 8143872
    Abstract: A power regulator for converting an input voltage to an output voltage includes a pass device, a reference signal circuit and an error amplifier. The pass device receives the input voltage and provides the output voltage at an output terminal of the power regulator. The reference signal circuit coupled to the output terminal is powered by the output voltage to provide a reference signal. The error amplifier coupled to the pass device is powered by the output voltage to compare the reference signal with a feedback signal indicative of the output voltage. The error amplifier can generate a control signal according to a result of the comparison to drive the pass device.
    Type: Grant
    Filed: May 26, 2009
    Date of Patent: March 27, 2012
    Assignee: O2Micro, Inc
    Inventors: Laszlo Lipcsei, Serban Mihai Popescu
  • Publication number: 20120025792
    Abstract: A controller for a power converter includes a first amplification stage and a second amplification stage coupled to the first amplification stage. The first amplification stage generates a first amplified signal at a first terminal of an energy storage element according to an output signal the power converter. The second amplification stage generates a second amplified signal at a second terminal of the energy storage element and varies the second amplified signal in response to a change in the output signal. The second amplification stage further decreases the variation of the second amplified signal based on the first amplified signal.
    Type: Application
    Filed: May 2, 2011
    Publication date: February 2, 2012
    Applicant: O2MICRO, INC.
    Inventors: Laszlo LIPCSEI, Serban Mihai POPESCU, Vlad Mihail Dan POPESCU-STANESTI
  • Publication number: 20120013315
    Abstract: A converter circuit includes a converter and a controller. The converter converts an input voltage to an output voltage. The controller receives a reference voltage, generates a slew voltage having a substantially constant first slew rate if the reference voltage changes from a first level to a second level, and controls the converter based on the slew voltage to cause the output voltage to change from a third level to a fourth level at a substantially constant second slew rate.
    Type: Application
    Filed: June 22, 2011
    Publication date: January 19, 2012
    Inventors: Serban Mihai POPESCU, Laszlo LIPCSEI, Marius PADURE, Guoyong GUO
  • Patent number: 8058817
    Abstract: A power system includes a current regulator coupled to a load and for generating an output current having a substantially constant ripple magnitude, and for adjusting the output current according to a sense signal indicative of the output current. In addition, the power system includes a filter element coupled in parallel with the load and for passing an AC (alternating-current) portion of the output current. Furthermore, the power system includes a current sensor coupled between ground and the parallel-coupled filtering element and load, and for providing the sense signal indicative of the output current.
    Type: Grant
    Filed: September 30, 2008
    Date of Patent: November 15, 2011
    Assignee: O2Micro, Inc.
    Inventors: Laszlo Lipcsei, Serban-Mihai Popescu, Sorin Hornet
  • Publication number: 20110254520
    Abstract: A controller includes an input selector, multiple cores and a multiplexer. The multiplexer is operable for multiplexing control signals to multiple output channels to provide multiple output signals. Each output channel can output a respective output signal, and each output signal represents a cyclic rotation of the control signals. The input selector is operable for enabling the cores to operate in a standby state alternately to control a multiplexing sequence of the control signals.
    Type: Application
    Filed: February 18, 2011
    Publication date: October 20, 2011
    Inventors: ChengHwa TEH, Laszlo LIPCSEI, Serban Mihai POPESCU
  • Patent number: 7893507
    Abstract: A transistor comprises a substrate of a first conductivity type, a drain region and a source region of a second conductivity type, a gate, a gate oxide layer, an adjustment implant region of the first conductivity type and a planar junction. The drain region and the source region are disposed in the substrate. The gate is placed over the substrate between the source region and the drain region. The gate is separated from the substrate by the gate oxide layer. The adjustment implant region is disposed under the gate oxide layer and in the substrate. A second doping concentration of the adjustment implant region is higher than a first doping concentration of the substrate. The adjustment implant region and the drain region in a predetermined shape form the planar junction with a surface curvature pointing towards the drain region to relax electrical field intensity at a location of the planar junction.
    Type: Grant
    Filed: January 16, 2009
    Date of Patent: February 22, 2011
    Assignee: O2Micro International Limited
    Inventors: Marian Udrea Spenea, Serban Mihai Popescu, Laszlo Lipcsei
  • Patent number: 7868693
    Abstract: An amplifier that receives an input signal and outputs an amplified output signal includes an integration stage, a comparison stage, and a full bridge circuit. The integration stage is be used for receiving a constant common mode voltage, for receiving a first signal representing the input signal of the amplifier, and for generating a ramp signal. The comparison stage coupled to the integration stage is used for generating a pulse width modulation signal according to the ramp signal and according to a hysteretic signal. The full bridge circuit coupled to the comparison stage is used for receiving a power supply and the pulse width modulation signal, and for generating the output of the amplifier.
    Type: Grant
    Filed: March 5, 2009
    Date of Patent: January 11, 2011
    Assignee: 02Micro International Limited
    Inventors: Marius Padure, Laszlo Lipcsei, Serban Mihai Popescu
  • Patent number: 7755500
    Abstract: A battery pack is disclosed. The battery pack includes a battery cell and a cell monitor. The cell monitor is embedded in the battery cell and is operable for monitoring the battery cell and for generating an alert signal indicative of a predetermined condition of the battery cell.
    Type: Grant
    Filed: November 30, 2007
    Date of Patent: July 13, 2010
    Assignee: O2 Micro, Inc.
    Inventors: Bill Densham, James Keim, Serban-Mihai Popescu
  • Publication number: 20100079088
    Abstract: A power system includes a current regulator coupled to a load and for generating an output current having a substantially constant ripple magnitude, and for adjusting the output current according to a sense signal indicative of the output current. In addition, the power system includes a filter element coupled in parallel with the load and for passing an AC (alternating-current) portion of the output current. Furthermore, the power system includes a current sensor coupled between ground and the parallel-coupled filtering element and load, and for providing the sense signal indicative of the output current.
    Type: Application
    Filed: September 30, 2008
    Publication date: April 1, 2010
    Inventors: Laszlo Lipcsei, Serban-Mihai Popescu, Sorin Hornet
  • Publication number: 20100066321
    Abstract: A current sensing circuit includes a first resistor, a second resistor and a sense amplifier. The first resistor converts a current flowing through the first resistor to a voltage drop between positive and negative sides of the first resistor. The second resistor is coupled to the negative side of the first resistor. The sense amplifier is coupled to the positive side of the first resistor via a first pin of the sense amplifier, and coupled to the negative side of the first resistor through the second resistor via a second pin of the sense amplifier. The sense amplifier employs a negative feedback to generate a sensing current proportional to the current flowing through the first resistor.
    Type: Application
    Filed: March 18, 2009
    Publication date: March 18, 2010
    Inventors: Serban Mihai POPESCU, Cristian ANDREEV
  • Publication number: 20100052783
    Abstract: An amplifier that receives an input signal and outputs an amplified output signal includes an integration stage, a comparison stage, and a full bridge circuit. The integration stage is be used for receiving a constant common mode voltage, for receiving a first signal representing the input signal of the amplifier, and for generating a ramp signal. The comparison stage coupled to the integration stage is used for generating a pulse width modulation signal according to the ramp signal and according to a hysteretic signal. The full bridge circuit coupled to the comparison stage is used for receiving a power supply and the pulse width modulation signal, and for generating the output of the amplifier.
    Type: Application
    Filed: March 5, 2009
    Publication date: March 4, 2010
    Inventors: Marius PADURE, Laszlo LIPCSEI, Serban-Mihai POPESCU