Patents by Inventor Kyoung Wook Seok
Kyoung Wook Seok 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: 9106139Abstract: A Low Forward Voltage Rectifier (LFVR) includes a bipolar transistor, a parallel diode, and a base current injection circuit disposed in an easy-to-employ two-terminal package. In one example, the transistor is a Reverse Bipolar Junction Transistor (RBJT), the diode is a distributed diode, and the base current injection circuit is a current transformer. Under forward bias conditions (when the voltage from the first package terminal to the second package terminal is positive), the LFVR conducts current at a rated current level with a low forward voltage drop (for example, approximately 0.1 volts). In reverse bias conditions, the LFVR blocks current flow. Using the LFVR in place of a conventional silicon diode rectifier in the secondary of a flyback converter reduces average power dissipation and increases power supply efficiency.Type: GrantFiled: January 7, 2014Date of Patent: August 11, 2015Assignee: IXYS CorporationInventor: Kyoung Wook Seok
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Publication number: 20150200184Abstract: A full bridge rectifier includes four bipolar transistors, each of which has an associated parallel diode. A first pair of inductors provides inductive current splitting and thereby provides base current to/from one pair of the bipolar transistors so that the collector-to-emitter voltages of the bipolar transistors are low. A second pair of inductors similarly provides inductive current splitting to provide base current to/from the other pair of bipolar transistors. In one embodiment, all components are provided in a four terminal full bridge rectifier module. The module can be used as a drop-in replacement for a conventional four terminal full bridge diode rectifier. When current flows through the rectifier module, however, the voltage drop across the module is less than one volt. Due to the reduced low voltage drop, power loss in the rectifier module is reduced as compared to power loss in a conventional full bridge diode rectifier.Type: ApplicationFiled: March 27, 2015Publication date: July 16, 2015Inventor: Kyoung Wook Seok
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Patent number: 9082845Abstract: A split-body Super Junction FET is made using only seven masks. Thin oxide is disposed on an upper semiconductor surface of a super junction charge compensation region. A polysilicon gate is disposed on the thin oxide. An ILD (InterLayer Dielectric) layer is disposed on the upper surface of the thin oxide so that the ILD layer covers the polysilicon gate. A gate bus line metal structure and a field plate metal structure are disposed on the upper surface of the ILD. A portion of the upper surface of the ILD extends from the gate bus line metal, laterally over floating rings, and to the field plate metal. This portion of the upper surface of the ILD layer is substantially planar where the ILD layer passes over the floating rings. The field plate metal structure, a polysilicon feature, and a diffusion region together form a stepped depletion layer field plate structure.Type: GrantFiled: March 31, 2014Date of Patent: July 14, 2015Assignee: IXYS CorporationInventor: Kyoung Wook Seok
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Publication number: 20150155785Abstract: A switching converter has a self-driven bipolar junction transistor (BJT) synchronous rectifier. The BJT rectifier includes a BJT and a parallel-connected diode, and has a low forward voltage drop. In a first portion of a switching cycle, a main switch is on and the BJT rectifier is off. Current flows from an input, through the main switch, through the first inductor, to an output. Current also flows through the main switch, through the second inductor, to the output. In a second portion of the cycle, the main switch is turned off but the inductor currents continue to flow. Current flows from a ground node, through the BJT rectifier, through the first inductor, to the output. The BJT is on due to the second inductor drawing a base current from the BJT. In one example, the main switch is a split-source NFET that conducts separate currents through the two inductors.Type: ApplicationFiled: November 30, 2013Publication date: June 4, 2015Applicant: IXYS CorporationInventor: Kyoung Wook Seok
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Patent number: 9042143Abstract: A Low Forward Voltage Rectifier (LFVR) circuit includes a bipolar transistor, a parallel diode, and a capacitive current splitting network. The LFVR circuit, when it is performing a rectifying function, conducts the forward current from a first node to a second node provided that the voltage from the first node to the second node is adequately positive. The capacitive current splitting network causes a portion of the forward current to be a base current of the bipolar transistor, thereby biasing the transistor so that the forward current experiences a low forward voltage drop across the transistor. The LFVR circuit sees use in as a rectifier in many different types of switching power converters, including in flyback, Cuk, SEPIC, boost, buck-boost, PFC, half-bridge resonant, and full-bridge resonant converters. Due to the low forward voltage drop across the LFVR, converter efficiency is improved.Type: GrantFiled: May 22, 2013Date of Patent: May 26, 2015Assignee: IXYS CorporationInventor: Kyoung Wook Seok
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Patent number: 9041075Abstract: A full bridge rectifier includes four bipolar transistors, each of which has an associated parallel diode. A first pair of inductors provides inductive current splitting and thereby provides base current to/from one pair of the bipolar transistors so that the collector-to-emitter voltages of the bipolar transistors are low. A second pair of inductors similarly provides inductive current splitting to provide base current to/from the other pair of bipolar transistors. In one embodiment, all components are provided in a four terminal full bridge rectifier module. The module can be used as a drop-in replacement for a conventional four terminal full bridge diode rectifier. When current flows through the rectifier module, however, the voltage drop across the module is less than one volt. Due to the reduced low voltage drop, power loss in the rectifier module is reduced as compared to power loss in a conventional full bridge diode rectifier.Type: GrantFiled: June 28, 2013Date of Patent: May 26, 2015Assignee: IXYS CorporationInventor: Kyoung Wook Seok
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Publication number: 20150138839Abstract: An AC-to-DC converter circuit includes DC-to-DC converter that in turn includes a secondary side circuit. The secondary side circuit includes a secondary winding, a pair of bipolar transistor-based self-driven synchronous rectifiers, a pair of current splitting inductors, and an output capacitor. Each of the synchronous rectifiers includes a bipolar transistor and a diode whose anode is coupled to the transistor collector and whose cathode is coupled to the transistor emitter. The current splitting inductors provide the necessary base current to the bipolar transistors at the appropriate times such that the bipolar transistors operate as synchronous rectifiers.Type: ApplicationFiled: November 18, 2013Publication date: May 21, 2015Applicant: IXYS CORPORATIONInventor: Kyoung Wook Seok
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Patent number: 8900943Abstract: A process for fabrication of a power semiconductor device is disclosed in which a single photomask is used to define each of p-conductivity well regions and n-conductivity type source regions. In the process a single photomask is deposited on a layer of polysilicon on a wafer, the polysilicon layer is removed from first regions of the power semiconductor device where the p-conductivity well regions and the n-conductivity type source regions are to be formed, and both p-conductivity type and n-conductivity type dopants are introduced into the wafer through the first regions.Type: GrantFiled: May 31, 2014Date of Patent: December 2, 2014Assignee: IXYS CorporationInventors: Kyoung Wook Seok, Jae Yong Choi, Vladimir Tsukanov
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Publication number: 20140273357Abstract: A process for fabrication of a power semiconductor device is disclosed in which a single photomask is used to define each of p-conductivity well regions and n-conductivity type source regions. In the process a single photomask is deposited on a layer of polysilicon on a wafer, the polysilicon layer is removed from first regions of the power semiconductor device where the p-conductivity well regions and the n-conductivity type source regions are to be formed, and both p-conductivity type and n-conductivity type dopants are introduced into the wafer through the first regions.Type: ApplicationFiled: May 31, 2014Publication date: September 18, 2014Applicant: IXYS CorporationInventors: Kyoung Wook Seok, Jae Yong Choi, Vladimir Tsukanov
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Publication number: 20140273384Abstract: A field-effect transistor involves a drain electrode, a drift region, a body region, a source region, a gate insulator layer, and a gate electrode. The drift region is disposed above the drain electrode. The body region extends down into the drift region from a first upper semiconductor surface. The source region is ladder-shaped and extends down in the body region from a second upper semiconductor surface. The first and second upper semiconductor surfaces are substantially planar and are not coplanar. A first portion of the body region is surrounded laterally by a second portion of the body region. The second portion of the body region and the drift region meet at a body-to-drift boundary. The body-to-drift boundary has a central portion that is non-planar. A gate insulator layer is disposed over the source region and a gate electrode is disposed over the gate insulator.Type: ApplicationFiled: May 30, 2014Publication date: September 18, 2014Applicant: IXYS CorporationInventor: Kyoung Wook Seok
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Patent number: 8742451Abstract: A field-effect transistor involves a drain electrode, a drift region, a body region, a source region, a gate insulator layer, and a gate electrode. The drift region is disposed above the drain electrode. The body region extends down into the drift region from a first upper semiconductor surface. The source region is ladder-shaped and extends down in the body region from a second upper semiconductor surface. The first and second upper semiconductor surfaces are substantially planar and are not coplanar. A first portion of the body region is surrounded laterally by a second portion of the body region. The second portion of the body region and the drift region meet at a body-to-drift boundary. The body-to-drift boundary has a central portion that is non-planar. A gate insulator layer is disposed over the source region and a gate electrode is disposed over the gate insulator.Type: GrantFiled: March 7, 2012Date of Patent: June 3, 2014Assignee: IXYS CorporationInventor: Kyoung Wook Seok
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Patent number: 8741709Abstract: A process for fabrication of a power semiconductor device is disclosed in which a single photomask is used to define each of p-conductivity well regions and n-conductivity type source regions. In the process a single photomask is deposited on a layer of polysilicon on a wafer, the polysilicon layer is removed from first regions of the power semiconductor device where the p-conductivity well regions and the n-conductivity type source regions are to be formed, and both p-conductivity type and n-conductivity type dopants are introduced into the wafer through the first regions.Type: GrantFiled: May 23, 2011Date of Patent: June 3, 2014Assignee: IXYS CorporationInventors: Kyoung Wook Seok, Jae Yong Choi, Vladimir Tsukanov
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Patent number: 8737094Abstract: A flyback converter involves a bipolar transistor (BJT) and a parallel-connected diode as the rectifying element in the secondary side of the converter. The transformer of the converter has a primary winding, a first secondary winding, and a second secondary winding. A first end of the first secondary winding is coupled to the BJT base. A first end of the second secondary winding is coupled to the BJT collector and to the anode of the diode. The first and second secondary windings are wound such that when primary winding current stops, pulses of current flow out of the first ends of the first and second secondary windings. These currents are such that the BJT is maintained in saturation throughout at least most of the time current flows through the rectifying element, thereby achieving a low forward voltage across the rectifying element, reducing conduction loss, and increasing converter efficiency.Type: GrantFiled: November 17, 2011Date of Patent: May 27, 2014Assignee: IXYS CorporationInventors: Kyoung Wook Seok, Joseph James Roosma
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Publication number: 20140118055Abstract: An IGBT die structure includes an auxiliary P well region. A terminal, that is not connected to any other IGBT terminal, is coupled to the auxiliary P well region. To accelerate IGBT turn on, a current is injected into the terminal during the turn on time. The injected current causes charge carriers to be injected into the N drift layer of the IGBT, thereby reducing turn on time. To accelerate IGBT turn off, charge carriers are removed from the N drift layer by drawing current out of the terminal. To reduce VCE(SAT), current can also be injected into the terminal during IGBT on time. An IGBT assembly involves the IGBT die structure and an associated current injection/extraction circuit. As appropriate, the circuit injects or extracts current from the terminal depending on whether the IGBT is in a turn on time or is in a turn off time.Type: ApplicationFiled: October 26, 2012Publication date: May 1, 2014Applicant: IXYS CorporationInventor: Kyoung Wook Seok
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Publication number: 20140119064Abstract: A Low Forward Voltage Rectifier (LFVR) includes a bipolar transistor, a parallel diode, and a base current injection circuit disposed in an easy-to-employ two-terminal package. In one example, the transistor is a Reverse Bipolar Junction Transistor (RBJT), the diode is a distributed diode, and the base current injection circuit is a current transformer. Under forward bias conditions (when the voltage from the first package terminal to the second package terminal is positive), the LFVR conducts current at a rated current level with a low forward voltage drop (for example, approximately 0.1 volts). In reverse bias conditions, the LFVR blocks current flow. Using the LFVR in place of a conventional silicon diode rectifier in the secondary of a flyback converter reduces average power dissipation and increases power supply efficiency.Type: ApplicationFiled: January 7, 2014Publication date: May 1, 2014Applicant: IXYS CorporationInventor: Kyoung Wook Seok
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Patent number: 8686513Abstract: An IGBT die structure includes an auxiliary P well region. A terminal, that is not connected to any other IGBT terminal, is coupled to the auxiliary P well region. To accelerate IGBT turn on, a current is injected into the terminal during the turn on time. The injected current causes charge carriers to be injected into the N drift layer of the IGBT, thereby reducing turn on time. To accelerate IGBT turn off, charge carriers are removed from the N drift layer by drawing current out of the terminal. To reduce VCE(SAT), current can also be injected into the terminal during IGBT on time. An IGBT assembly involves the IGBT die structure and an associated current injection/extraction circuit. As appropriate, the circuit injects or extracts current from the terminal depending on whether the IGBT is in a turn on time or is in a turn off time.Type: GrantFiled: October 26, 2012Date of Patent: April 1, 2014Assignee: IXYS CorporationInventor: Kyoung Wook Seok
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Patent number: 8649199Abstract: A Low Forward Voltage Rectifier (LFVR) includes a bipolar transistor, a parallel diode, and a base current injection circuit disposed in an easy-to-employ two-terminal package. In one example, the transistor is a Reverse Bipolar Junction Transistor (RBJT), the diode is a distributed diode, and the base current injection circuit is a current transformer. Under forward bias conditions (when the voltage from the first package terminal to the second package terminal is positive), the LFVR conducts current at a rated current level with a low forward voltage drop (for example, approximately 0.1 volts). In reverse bias conditions, the LFVR blocks current flow. Using the LFVR in place of a conventional silicon diode rectifier in the secondary of a flyback converter reduces average power dissipation and increases power supply efficiency.Type: GrantFiled: October 29, 2011Date of Patent: February 11, 2014Assignee: IXYS CorporationInventor: Kyoung Wook Seok
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Patent number: 8648399Abstract: A Reverse Bipolar Junction Transistor (RBJT) integrated circuit comprises a bipolar transistor and a parallel-coupled distributed diode. The bipolar transistor involves many N-type collector regions. Each N-type collector region has a central hole so that P-type material from an underlying P-type region extends up into the hole. A collector metal electrode covers the central hole forming a diode contact at the top of the hole. When the distributed diode conducts, current flows from the collector electrode, down through the many central holes in the many collector regions, through corresponding PN junctions, and to an emitter electrode disposed on the bottom side of the IC. The RBJT and distributed diode integrated circuit has emitter-to-collector and emitter-to-base reverse breakdown voltages exceeding twenty volts. The collector metal electrode is structured to contact the collector regions, and to bridge over the base electrode, resulting in a low collector-to-emitter voltage when the RBJT is on.Type: GrantFiled: November 17, 2011Date of Patent: February 11, 2014Assignee: IXYS CorporationInventor: Kyoung Wook Seok
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Publication number: 20130285210Abstract: A full bridge rectifier includes four bipolar transistors, each of which has an associated parallel diode. A first pair of inductors provides inductive current splitting and thereby provides base current to/from one pair of the bipolar transistors so that the collector-to-emitter voltages of the bipolar transistors are low. A second pair of inductors similarly provides inductive current splitting to provide base current to/from the other pair of bipolar transistors. In one embodiment, all components are provided in a four terminal full bridge rectifier module. The module can be used as a drop-in replacement for a conventional four terminal full bridge diode rectifier. When current flows through the rectifier module, however, the voltage drop across the module is less than one volt. Due to the reduced low voltage drop, power loss in the rectifier module is reduced as compared to power loss in a conventional full bridge diode rectifier.Type: ApplicationFiled: June 28, 2013Publication date: October 31, 2013Inventor: Kyoung Wook Seok
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Publication number: 20130249529Abstract: A Low Forward Voltage Rectifier (LFVR) circuit includes a bipolar transistor, a parallel diode, and a capacitive current splitting network. The LFVR circuit, when it is performing a rectifying function, conducts the forward current from a first node to a second node provided that the voltage from the first node to the second node is adequately positive. The capacitive current splitting network causes a portion of the forward current to be a base current of the bipolar transistor, thereby biasing the transistor so that the forward current experiences a low forward voltage drop across the transistor. The LFVR circuit sees use in as a rectifier in many different types of switching power converters, including in flyback, Cuk, SEPIC, boost, buck-boost, PFC, half-bridge resonant, and full-bridge resonant converters. Due to the low forward voltage drop across the LFVR, converter efficiency is improved.Type: ApplicationFiled: May 22, 2013Publication date: September 26, 2013Applicant: IXYS CorporationInventor: Kyoung Wook Seok