Patents by Inventor Walter Wohlmuth
Walter Wohlmuth 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: 20230282645Abstract: A semiconductor device includes an insulating layer, a semiconductor layer, and a compound semiconductor stacked layer disposed on a substrate in sequence, a first transistor, a second transistor, an isolation structure, and a conductive structure. The first transistor is disposed in a first device region and on the compound semiconductor stacked layer. The second transistor is disposed in a second device region and on the compound semiconductor stacked layer. The isolation structure is disposed between the first and second transistors. The conductive structure is disposed in the second device region, passes through the compound semiconductor stacked layer, and electrically connects the semiconductor layer to a second source of the second transistor. There is no electrical connection between the semiconductor layer in the first device region and a first source of the first transistor.Type: ApplicationFiled: March 2, 2022Publication date: September 7, 2023Applicant: Vanguard International Semiconductor CorporationInventors: Walter Wohlmuth, Shin-Cheng Lin, Chia-Ching Huang
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Patent number: 7952150Abstract: The present invention relates to providing an enhancement-mode (e-mode) Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET) with a complementary depletion-mode (d-mode) FET on a common group III-V substrate. The depletion mode FET may be another MOSFET, a MEtal-Semiconductor FET (MESFET), a High Electron Mobility Transistor (HEMT), or like FET structure. In particular, the e-mode MOSFET includes a gate structure that resides between source and drain structures on a transistor body. The gate structure includes a gate contact that is separated from the transistor body by a gate oxide. The gate oxide is an oxidized material that includes Indium and Phosphorus. The gate oxide is formed beneath the gate contact.Type: GrantFiled: June 5, 2009Date of Patent: May 31, 2011Assignee: RF Micro Devices, Inc.Inventor: Walter A. Wohlmuth
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Patent number: 7881029Abstract: The present invention relates to an electrostatic discharge (ESD) clamp circuit that is used to protect other circuitry from high voltage ESD events. The ESD clamp circuit may include a field effect transistor (FET) element as a clamping element, which is triggered by using a drain-to-gate capacitance and a drain-to-gate resistance of the FET element and a resistive element as a voltage divider to divide down an ESD voltage to provide a triggering gate voltage of the FET element. In its simplest embodiment, the ESD clamp circuit includes only an FET element, a resistive element, a source-coupled level shifting diode, and a reverse protection diode. Therefore, the ESD clamp circuit may be small compared to other ESD protection circuits. The simplicity of the ESD clamp circuit may minimize parasitic capacitances, thereby maximizing linearity of the ESD clamp circuit over a wide frequency range.Type: GrantFiled: July 7, 2008Date of Patent: February 1, 2011Assignee: RF Micro Devices, Inc.Inventors: Jason Yuxin Li, Walter A. Wohlmuth, Swaminathan Muthukrishnan, Christian Rye Iversen, Nathaniel Peachey
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Patent number: 7881030Abstract: The present invention relates to an electrostatic discharge (ESD) clamp circuit that is used to protect other circuitry from high voltage ESD events. The ESD clamp circuit may include a field effect transistor (FET) element as a clamping element, which is triggered by using a drain-to-gate capacitance, a drain-to-gate resistance, or both of the FET element, and a resistive element as a voltage divider to divide down an ESD voltage to provide a triggering gate voltage of the FET element. In its simplest embodiment, the ESD clamp circuit includes only an FET element and a resistive element. Therefore, the single FET element ESD clamp circuit may be small compared to other ESD protection circuits. The simplicity of the ESD clamp circuit may minimize parasitic capacitances, thereby maximizing linearity of the ESD clamp circuit over a wide frequency range.Type: GrantFiled: July 7, 2008Date of Patent: February 1, 2011Assignee: RF Micro Devices, Inc.Inventors: Jason Yuxin Li, Walter A. Wohlmuth, Swaminathan Muthukrishnan, Christian Rye Iversen, Nathaniel Peachey
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Patent number: 7656002Abstract: The present invention relates to a microelectronic device having a bipolar epitaxial structure that provides at least one bipolar transistor element formed over at least one field effect transistor (FET) epitaxial structure that provides at least one FET element. The epitaxial structures are separated with at least one separation layer. Additional embodiments of the present invention may use different epitaxial layers, epitaxial sub-layers, metallization layers, isolation layers, layer materials, doping materials, isolation materials, implant materials, or any combination thereof.Type: GrantFiled: November 30, 2007Date of Patent: February 2, 2010Assignee: RF Micro Devices, Inc.Inventors: Curtis A. Barratt, Michael T. Fresina, Brian G. Moser, Dain C. Miller, Walter A. Wohlmuth
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Patent number: 7368980Abstract: An exemplary circuit embodiment includes a depletion-mode transistor and an enhancement-mode transistor. The circuit also includes a circuit portion coupled to a gate region of the depletion-mode transistor and to a gate region of the enhancement-mode transistor. In this embodiment, the circuit portion is configured to provide a reference voltage at an output node, wherein the reference voltage is associated with a difference between a voltage at the gate region of the depletion-mode transistor and a voltage at the gate region of the enhancement-mode transistor.Type: GrantFiled: April 25, 2005Date of Patent: May 6, 2008Assignee: TriQuint Semiconductor, Inc.Inventors: Rebouh Benelbar, Walter Wohlmuth
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Publication number: 20070023901Abstract: One embodiment of an integrated circuit includes a substrate, an electrical device positioned above the substrate, and a bond bad positioned above and aligned along a vertical axis with the electrical device such that the electrical device is positioned between the substrate and the bond pad.Type: ApplicationFiled: July 29, 2005Publication date: February 1, 2007Inventors: Gerard Mahoney, Matthew Essar, Walter Wohlmuth, Wayne Struble
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Publication number: 20060238234Abstract: An exemplary circuit embodiment includes a depletion-mode transistor and an enhancement-mode transistor. The circuit also includes a circuit portion coupled to a gate region of the depletion-mode transistor and to a gate region of the enhancement-mode transistor. In this embodiment, the circuit portion is configured to provide a reference voltage at an output node, wherein the reference voltage is associated with a difference between a voltage at the gate region of the depletion-mode transistor and a voltage at the gate region of the enhancement-mode transistor.Type: ApplicationFiled: April 25, 2005Publication date: October 26, 2006Inventors: Rebouh Benelbar, Walter Wohlmuth
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Publication number: 20060197129Abstract: One embodiment of a fin-field effect transistor includes a material stack including a non-inverting su surface channel, a fin of semiconductor material positioned on the material stack, the fin including first and second opposing side surfaces, and a gate electrode positioned on the first and second opposing side surfaces of the fin.Type: ApplicationFiled: March 3, 2005Publication date: September 7, 2006Inventor: Walter Wohlmuth
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Publication number: 20060027840Abstract: A depletion mode (D-mode) field effect transistor (FET) is monolithically integrated with an enhancement mode (E-mode) FET in a multi-layer structure. The multi-layer structure includes a channel layer overlaid by a barrier layer overlaid by an ohmic contact layer. Source and drain contacts of the D-mode and E-mode FETs are coupled to the ohmic contact layer. A gate contact of the D-mode and E-mode FETs is coupled to the barrier layer. An amorphized region is provided beneath the E-mode gate contact within the barrier layer. The amorphized region forms a buried E-mode Schottky contact with the barrier layer. An alternative embodiment couples the gate contact of the D-mode transistor to a first layer that overlies the barrier layer, and provides a similar D-mode amorphized region within the first layer.Type: ApplicationFiled: October 11, 2005Publication date: February 9, 2006Applicant: TriQuint Semiconductor, Inc.Inventor: Walter Wohlmuth
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Publication number: 20050110054Abstract: A depletion mode (D-mode) field effect transistor (FET) is monolithically integrated with an enhancement mode (E-mode) FET in a multi-layer structure. The multi-layer structure includes a channel layer overlaid by a barrier layer overlaid by an ohmic contact layer. Source and drain contacts of the D-mode and E-mode FETs are coupled to the ohmic contact layer. A gate contact of the D-mode and E-mode FETs is coupled to the barrier layer. An amorphized region is provided beneath the E-mode gate contact within the barrier layer. The amorphized region forms a buried E-mode Schottky contact with the barrier layer. An alternative embodiment couples the gate contact of the D-mode transistor to a first layer that overlies the barrier layer, and provides a similar D-mode amorphized region within the first layer.Type: ApplicationFiled: November 24, 2003Publication date: May 26, 2005Inventor: Walter Wohlmuth
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Patent number: 6697412Abstract: A light-emitting device includes a GaAs substrate, a light-emitting structure disposed above the substrate and capable of emitting light having a wavelength of about 1.3 microns to about 1.55 microns, and a buffer layer disposed between the substrate and the light-emitting structure. The composition of the buffer layer varies through the buffer layer such that a lattice constant of the buffer layer grades from a lattice constant approximately equal to a lattice constant of the substrate to a lattice constant approximately equal to a lattice constant of the light-emitting structure. The light-emitting device exhibits improved mechanical, electrical, thermal, and optical properties compared to similar light-emitting devices grown on InP substrates.Type: GrantFiled: April 13, 2001Date of Patent: February 24, 2004Assignee: TriQuint Semiconductor, Inc.Inventors: Edward A. Beam, III, Gary A. Evans, Paul Saunier, Ming-Yih Kao, David M. Fanning, William H. Davenport, Andy Turudic, Walter A. Wohlmuth
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Publication number: 20020150137Abstract: A light-emitting device includes a GaAs substrate, a light-emitting structure disposed above the substrate and capable of emitting light having a wavelength of about 1.3 microns to about 1.55 microns, and a buffer layer disposed between the substrate and the light-emitting structure. The composition of the buffer layer varies through the buffer layer such that a lattice constant of the buffer layer grades from a lattice constant approximately equal to a lattice constant of the substrate to a lattice constant approximately equal to a lattice constant of the light-emitting structure. The light-emitting device exhibits improved mechanical, electrical, thermal, and optical properties compared to similar light-emitting devices grown on InP substrates.Type: ApplicationFiled: April 13, 2001Publication date: October 17, 2002Inventors: Edward A. Beam, Gary A. Evans, Paul Saunier, Ming-Yih Kao, David M. Fanning, William H. Davenport, Andy Turudic, Walter A. Wohlmuth
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Patent number: 5880482Abstract: A low dark current metal-semiconductor-metal photodetector has an active region for receiving photons and generating charge carriers in the form of holes and electrons in response to the photons and an isolation region for allowing electrical coupling to occur without increasing the dark current. The photodetector is a III-V ternary semiconductor having its active region defined by a via through a dielectric layer. A pair of electrodes has contact portions extending into contact with the active region and terminating on the isolation region. One electrode of the pair provides a high Schottky barrier to holes.Type: GrantFiled: January 29, 1997Date of Patent: March 9, 1999Assignee: The Board of Trustees of the University of IlliniosInventors: Ilesanmi Adesida, Walter Wohlmuth, Mohamed Arafa, Patrick Fay