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).
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Patent number: 9083237Abstract: 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: GrantFiled: June 22, 2011Date of Patent: July 14, 2015Assignee: O2Micro, Inc.Inventors: Serban Mihai Popescu, Laszlo Lipcsei, Marius Padure, Guoyong Guo
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Patent number: 8624567Abstract: 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: GrantFiled: December 30, 2011Date of Patent: January 7, 2014Assignee: O2Micro, Inc.Inventor: Serban Mihai Popescu
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Patent number: 8610412Abstract: 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: GrantFiled: February 18, 2011Date of Patent: December 17, 2013Assignee: O2Micro Inc.Inventors: ChengHwa Teh, Laszlo Lipcsei, Serban Mihai Popescu
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Patent number: 8587276Abstract: 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: GrantFiled: May 2, 2011Date of Patent: November 19, 2013Assignee: O2Micro, Inc.Inventors: Laszlo Lipcsei, Serban Mihai Popescu, Vlad Mihail Dan Popescu-Stanesti
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Patent number: 8487595Abstract: 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: GrantFiled: June 12, 2012Date of Patent: July 16, 2013Assignee: 02Micro Inc.Inventors: Serban Mihai Popescu, Christian Andreev
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Publication number: 20130169254Abstract: 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: ApplicationFiled: December 30, 2011Publication date: July 4, 2013Inventor: Serban Mihai Popescu
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Publication number: 20120249098Abstract: 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: ApplicationFiled: June 12, 2012Publication date: October 4, 2012Applicant: O2Micro, Inc.Inventors: Serban Mihai POPESCU, Cristian ANDREEV
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Publication number: 20120206120Abstract: 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: ApplicationFiled: February 13, 2012Publication date: August 16, 2012Applicant: O2MICRO, INC.Inventors: Laszlo Lipcsei, Serban Mihai Popescu
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Patent number: 8232784Abstract: 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: GrantFiled: March 18, 2009Date of Patent: July 31, 2012Assignee: O2Micro, IncInventors: Serban Mihai Popescu, Cristian Andreev
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Patent number: 8143872Abstract: 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: GrantFiled: May 26, 2009Date of Patent: March 27, 2012Assignee: O2Micro, IncInventors: Laszlo Lipcsei, Serban Mihai Popescu
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Publication number: 20120025792Abstract: 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: ApplicationFiled: May 2, 2011Publication date: February 2, 2012Applicant: O2MICRO, INC.Inventors: Laszlo LIPCSEI, Serban Mihai POPESCU, Vlad Mihail Dan POPESCU-STANESTI
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Publication number: 20120013315Abstract: 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: ApplicationFiled: June 22, 2011Publication date: January 19, 2012Inventors: Serban Mihai POPESCU, Laszlo LIPCSEI, Marius PADURE, Guoyong GUO
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Patent number: 8058817Abstract: 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: GrantFiled: September 30, 2008Date of Patent: November 15, 2011Assignee: O2Micro, Inc.Inventors: Laszlo Lipcsei, Serban-Mihai Popescu, Sorin Hornet
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Publication number: 20110254520Abstract: 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: ApplicationFiled: February 18, 2011Publication date: October 20, 2011Inventors: ChengHwa TEH, Laszlo LIPCSEI, Serban Mihai POPESCU
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Patent number: 7893507Abstract: 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: GrantFiled: January 16, 2009Date of Patent: February 22, 2011Assignee: O2Micro International LimitedInventors: Marian Udrea Spenea, Serban Mihai Popescu, Laszlo Lipcsei
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Patent number: 7868693Abstract: 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: GrantFiled: March 5, 2009Date of Patent: January 11, 2011Assignee: 02Micro International LimitedInventors: Marius Padure, Laszlo Lipcsei, Serban Mihai Popescu
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Patent number: 7755500Abstract: 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: GrantFiled: November 30, 2007Date of Patent: July 13, 2010Assignee: O2 Micro, Inc.Inventors: Bill Densham, James Keim, Serban-Mihai Popescu
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Publication number: 20100079088Abstract: 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: ApplicationFiled: September 30, 2008Publication date: April 1, 2010Inventors: Laszlo Lipcsei, Serban-Mihai Popescu, Sorin Hornet
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Publication number: 20100066321Abstract: 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: ApplicationFiled: March 18, 2009Publication date: March 18, 2010Inventors: Serban Mihai POPESCU, Cristian ANDREEV
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Publication number: 20100052783Abstract: 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: ApplicationFiled: March 5, 2009Publication date: March 4, 2010Inventors: Marius PADURE, Laszlo LIPCSEI, Serban-Mihai POPESCU