Patents Assigned to ColdWatt, Inc.
  • Patent number: 7462891
    Abstract: A semiconductor device having at least one lateral channel with contacts on opposing surfaces thereof and a method of forming the same. In one embodiment, the semiconductor device includes a conductive substrate having a first contact covering a substantial portion of a bottom surface thereof. The semiconductor device also includes a lateral channel above the conductive substrate. The semiconductor device further includes a second contact above the lateral channel. The semiconductor device still further includes an interconnect having a sloped wall that connects the lateral channel to the conductive substrate. The interconnect is operable to provide a low resistance coupling between the first contact and the lateral channel. In a related but alternative embodiment, the first contact is a source contact and the second contact is a drain contact for the semiconductor device.
    Type: Grant
    Filed: September 27, 2005
    Date of Patent: December 9, 2008
    Assignee: ColdWatt, Inc.
    Inventors: Berinder P. S. Brar, Wonill Ha, James L. Vorhaus
  • Patent number: 7439557
    Abstract: A semiconductor device having a lateral channel with contacts on opposing surfaces thereof and a method of forming the same. In one embodiment, the semiconductor device includes a conductive substrate having a first contact covering a substantial portion of a bottom surface thereof. The semiconductor device also includes a lateral channel above the conductive substrate. The semiconductor device further includes a second contact above the lateral channel. The semiconductor device still further includes an interconnect that connects the lateral channel to the conductive substrate. The interconnect is operable to provide a low resistance coupling between the first contact and the lateral channel.
    Type: Grant
    Filed: March 29, 2005
    Date of Patent: October 21, 2008
    Assignee: ColdWatt, Inc.
    Inventors: Berinder P. S. Brar, Wonill Ha
  • Patent number: 7439556
    Abstract: A substrate driven field effect transistor (FET) and a method of forming the same. In one embodiment, the substrate driven FET includes a substrate having a source contact covering a substantial portion of a bottom surface thereof and a lateral channel above the substrate. The substrate driven FET also includes a drain contact above the lateral channel. The substrate driven FET still further includes a source interconnect that connects the lateral channel to the substrate operable to provide a low resistance coupling between the source contact and the lateral channel.
    Type: Grant
    Filed: March 29, 2005
    Date of Patent: October 21, 2008
    Assignee: ColdWatt, Inc.
    Inventors: Berinder P. S. Brar, Peter M. Asbeck
  • Patent number: 7431862
    Abstract: A method of forming nano composites within a polymer structure comprises exposing a wettable polymer having ion-exchangeable groups pendant therefrom to an aqueous solution of a soluble salt containing metal ions, the metal ions replacing, by ion exchange, the pendant groups on the polymer. After ion exchange the polymer is exposed to a reducing agent forming metal oxides trapped within the polymer structure.
    Type: Grant
    Filed: April 30, 2004
    Date of Patent: October 7, 2008
    Assignee: ColdWatt, Inc.
    Inventors: Vivek Mehrotra, Ira Goldberg
  • Patent number: 7427910
    Abstract: Cutout and/or keep away regions are etched in the winding structure near the gapped center leg of a magnetic core. This reduces eddy current losses caused by the leakage field and improves current uniformity and current sharing between windings thereby increasing converter efficiency. Windings closest to the air gap are suitably formed with both keep away regions and cutouts. Windings a little further away are formed with only cutouts, and the windings furthest away are unchanged. This approach keeps the net winding losses low in the presence of a fringing field. The precise configuration is determined by the core structure, air gap and winding arrangements.
    Type: Grant
    Filed: August 19, 2004
    Date of Patent: September 23, 2008
    Assignee: ColdWatt, inc.
    Inventors: Vivek Mehrotra, Jian Sun
  • Publication number: 20080224812
    Abstract: There is provided an isolated power converter. More particularly, in one embodiment, there is provided a power converter including a first magnetic core having a primary winding and a secondary winding around the first magnetic core. The power converter also includes a second magnetic core having a first leg, a second leg coupled to the first leg, and a third leg coupled to the first and second legs, wherein a part of the third leg is equidistant from the first leg and the second leg. The power converter also has a first winding encircling the first leg, a first end of the first winding coupled to the secondary winding, a second winding encircling the second leg, a first end of the second winding coupled to the secondary winding, and a third winding encircling the third leg, a first end of the third winding coupled to a second end of the first wining and to a second end of the second winding.
    Type: Application
    Filed: March 14, 2007
    Publication date: September 18, 2008
    Applicant: COLDWATT, INC.
    Inventor: Sriram Chandrasekaran
  • Patent number: 7417875
    Abstract: A power converter having input and output nodes and a method of operating the same. In one embodiment, the power converter includes a switching circuit including first, second and third active phase legs. Each of the first, second and third active legs includes a first switch coupled to one of the input nodes and a second switch coupled to another of the input nodes and has a common switching node therebetween. The power converter further includes a magnetic device including first, second and third primary windings, and first, second and third secondary windings. The first, second and third primary windings are coupled to the common switching node of the first, second and third active phase legs, respectively. The power converter still further includes a rectifier including first, second and third rectifier elements interposed between the first, second and third secondary windings, respectively, and one of the output nodes.
    Type: Grant
    Filed: February 8, 2006
    Date of Patent: August 26, 2008
    Assignee: ColdWatt, Inc.
    Inventors: Sriram Chandrasekaran, Vivek Mehrotra
  • Patent number: 7385375
    Abstract: A control circuit for a power converter employing a depletion mode switch and a method of operating the same. In one embodiment, the control circuit includes a controller configured to control the depletion mode switch by providing a drive signal to a control terminal thereof as a function of a characteristic of the power converter. The control circuit also includes a protection circuit configured to induce an application of a drive signal having a non-zero value to the control terminal to substantially disable the depletion mode switch in response to a transient condition of the power converter.
    Type: Grant
    Filed: February 23, 2006
    Date of Patent: June 10, 2008
    Assignee: ColdWatt, Inc.
    Inventor: Allen F. Rozman
  • Patent number: 7339208
    Abstract: A semiconductor device having multiple lateral channels with contacts on opposing surfaces thereof and a method of forming the same. In one embodiment, the semiconductor device includes a conductive substrate having a first contact covering a substantial portion of a bottom surface thereof. The semiconductor device also includes a first lateral channel above the conductive substrate and a second lateral channel above the first lateral channel. The semiconductor device further includes a second contact above the second lateral channel. The semiconductor device still further includes an interconnect that connects the first and second lateral channels to the conductive substrate operable to provide a low resistance coupling between the first contact and the first and second lateral channels.
    Type: Grant
    Filed: May 13, 2005
    Date of Patent: March 4, 2008
    Assignee: ColdWatt, Inc.
    Inventors: Berinder P. S. Brar, Wonill Ha
  • Patent number: 7321283
    Abstract: A vertical winding structure for planar integrated magnetics used in switched-mode power converters maintains close coupling between the different windings but reduces the eddy current losses, lowers the DC winding resistance and reduces the number of layers of the PCB. Vertical and horizontal windings can be used together without sacrificing these performance advantages and further minimizing the capacitive coupling between the outer-leg windings and the center-leg winding. This winding structure can be used in a wide range of magnetic structures including isolated and non-isolated CDRs, interleaved CDRs, and buck and boost converters.
    Type: Grant
    Filed: August 19, 2004
    Date of Patent: January 22, 2008
    Assignee: ColdWatt, Inc.
    Inventors: Vivek Mehrotra, Jian Sun, Sriram Chandrasekaran
  • Patent number: 7298118
    Abstract: A power converter employing a tapped inductor and method of operating the same. In one embodiment, the power converter includes first and second tapped inductors including a tapped winding having a first section and a second section with a tap therebetween. The power converter also includes first and second active phase legs including a main switch series-coupled with an input node of the power converter and the first section of the tapped windings of the first and second tapped inductors, respectively. The first and second active phase legs also include an auxiliary switch interposed between the second section of the tapped windings of the first and second tapped inductors, respectively, and an output node of the power converter.
    Type: Grant
    Filed: January 19, 2007
    Date of Patent: November 20, 2007
    Assignee: ColdWatt, Inc.
    Inventor: Sriram Chandrasekaran
  • Patent number: 7285807
    Abstract: A semiconductor device including a substrate driven field-effect transistor with a lateral channel and a parallel-coupled Schottky diode, and a method of forming the same. In one embodiment, the substrate driven field-effect transistor of the semiconductor device includes a conductive substrate having a first contact covering a substantial portion of a bottom surface thereof, and a lateral channel above the conductive substrate. The substrate driven field-effect transistor also includes a second contact above the lateral channel and an interconnect that connects the lateral channel to the conductive substrate operable to provide a low resistance coupling between the first contact and the lateral channel. The semiconductor device also includes a Schottky diode parallel-coupled to the substrate driven field-effect transistor. A first and second terminal of the Schottky diode are couplable to the first and second contacts, respectively, of the substrate drive field-effect transistor.
    Type: Grant
    Filed: August 25, 2005
    Date of Patent: October 23, 2007
    Assignee: ColdWatt, Inc.
    Inventors: Berinder P. S. Brar, Wonill Ha
  • Patent number: 7280026
    Abstract: A matrix integrated magnetics (MIM) “Extended E” core in which a plurality of outer legs are disposed on a base and separated along a first outer edge to define windows therebetween. A center leg is disposed on the top region of the base and separated from the outer legs to define a center window. The center leg is suitably positioned along a second outer edge opposite the first or between outer legs positioned along opposing outer edges. A plate is disposed on the outer legs opposite the base.
    Type: Grant
    Filed: August 19, 2004
    Date of Patent: October 9, 2007
    Assignee: ColdWatt, Inc.
    Inventors: Sriram Chandrasekaran, Vivek Mehrotra
  • Patent number: 7176662
    Abstract: A power converter employing a tapped inductor and method of operating the same. In one embodiment, the power converter includes first and second tapped inductors including a tapped winding having a first section and a second section with a tap therebetween. The power converter also includes first and second active phase legs including a main switch series-coupled with an input node of the power converter and the first section of the tapped windings of the first and second tapped inductors, respectively. The first and second active phase legs also include an auxiliary switch interposed between the second section of the tapped windings of the first and second tapped inductors, respectively, and an output node of the power converter.
    Type: Grant
    Filed: February 23, 2006
    Date of Patent: February 13, 2007
    Assignee: ColdWatt, Inc.
    Inventor: Sriram Chandrasekaran
  • Patent number: 7046523
    Abstract: There is disclosed a core structure with a very low profile, high power density and lower losses. The disclosed design allows for a larger core area where the DC fluxes are added, thereby reducing the air-gap requirements in the cores derived from low saturation density materials such as ferrites. The cellular nature of the design can be effectively employed in vertically packaged power converters and modules. Also disclosed is a DC-DC converter topology which preferably employs the disclosed core. N AC drive voltages drive N current doubler rectifiers (CDRs) in accordance with the symmetric modulation scheme; each CDR provides two rectified output currents to an output node. Each AC drive voltage has a switching period Ts. The drive voltages are phase-shifted by Ts/(2*N), such that the rectified output currents of the CDRs are interleaved, thereby reducing output voltage ripple.
    Type: Grant
    Filed: November 21, 2002
    Date of Patent: May 16, 2006
    Assignee: ColdWatt, Inc.
    Inventors: Jian Sun, Xiukuan Jing, Sriram Chandrasekaran, Vivek Mehrotra
  • Patent number: 7012414
    Abstract: A vertically packaged cellular power converter solves the problems associated with conventional designs and paves the way for a cellular circuit architecture with ultra-low interconnect resistance and inductance. The vertical packaging results in a power flow in the vertical direction (from the bottom to the top) with very short internal interconnects, thereby minimizing the associated conduction losses and permitting high conversion efficiency at high currents. The cellular architecture is ideally suited for generating multiple supply voltages.
    Type: Grant
    Filed: August 19, 2004
    Date of Patent: March 14, 2006
    Assignee: ColdWatt, Inc.
    Inventors: Vivek Mehrotra, Jian Sun, Sriram Chandrasekaran
  • Patent number: 6980077
    Abstract: A composite magnetic core formed of a high permeability material and a lower permeability, high saturation flux density material prevents core saturation without an air gap and reduces eddy current losses and loss of inductance. The composite core is configured such that the low permeability, high saturation material is located where the flux accumulates from the high permeability sections. The presence of magnetic material having a relatively high permeability keeps the flux confined within the core thereby preventing fringing flux from spilling out into the winding arrangement. This composite core configuration balances the requirements of preventing core saturation and minimizing eddy current losses without increasing either the height or width of the core or the number of windings.
    Type: Grant
    Filed: August 19, 2004
    Date of Patent: December 27, 2005
    Assignee: ColdWatt, Inc.
    Inventors: Sriram Chandrasekaran, Vivek Mehrotra, Jian Sun