Patents by Inventor David John Marshall
David John Marshall 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: 6876224Abstract: A method of enhancing noise margin on digital signal lines of a system includes steps of evaluating impedances and lengths of the digital signal lines. Resonances of each digital signal line are determined, and target waveforms for each digital signal line optimized for noise margin are determined. A configuration is generated for a programmable device driver to configure the device driver to generate the waveform optimized for noise margin. An alternative embodiment selects waveforms, and corresponding configurations, from a group of possible waveforms at boot time to ensure that data is transferred with optimum noise margins. Also claimed is apparatus embodying bus drivers capable of driving a bus with a waveform approximating blended trapezoidal and sinusoidal edge shapes, this waveform being optimum for noise margin in certain systems having multidrop busses.Type: GrantFiled: November 5, 2002Date of Patent: April 5, 2005Assignee: Hewlett-Packard Development Company, L.P.Inventors: David John Marshall, Philip L. Barnes, Larry Jay Thayer
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Patent number: 6828828Abstract: A reference voltage is moved dynamically towards a voltage level of the last received value. The movement takes place over a predetermined fraction of a bit-time. The amount of movement is limited so that successive logical values don't result in an unusable reference voltage level. When the output of a receiver changes, a state machine sequences the selection of analog reference voltage inputs to a multiplexer to move an output reference voltage towards a steady-state signal voltage level for the value that was just received. When the sequence is complete, the state machine keeps the last value selected on the output until the output of the receiver changes value.Type: GrantFiled: August 3, 2001Date of Patent: December 7, 2004Assignee: Hewlett-Packard Development Company, L.P.Inventors: David John Marshall, Karl Joseph B is, David W. Quint
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Patent number: 6825699Abstract: Buffer that includes an input node, an output node, and a three-transistor charge pump circuit is coupled to the input node and the output node. The buffer generates an output signal that is a delayed version of a signal presented at the input node. The three-transistor charge pump includes a first transistor (e.g., a pass transistor) that includes a drain electrode that is coupled to the input node, a gate electrode and a source electrode; a second transistor that includes a drain electrode that is coupled to a first predetermined voltage, a gate electrode coupled to the drain electrode of the second transistor, and a source electrode coupled to the gate electrode of the first transistor; and a capacitive element that includes a first electrode that is coupled to the source electrode of the second transistor and the gate electrode of the first transistor and a second electrode that is coupled to the output node.Type: GrantFiled: January 31, 2003Date of Patent: November 30, 2004Assignee: Hewlett-Packard Development Company, L.P.Inventors: David John Marshall, Ian Erickson, Michael H. Cogdill
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Patent number: 6798254Abstract: A reference voltage is moved dynamically towards a voltage level of the last received value. The movement takes place over a predetermined fraction of a bit-time. The amount of movement is limited so that successive logical values don't result in an unusable reference voltage level. When the output of a receiver changes, a state machine sequences the selection of analog reference voltage inputs to a multiplexer to move an output reference voltage towards a steady-state signal voltage level for the value that was just received. When the sequence is complete, the state machine keeps the last value selected on the output until the output of the receiver changes value.Type: GrantFiled: May 29, 2003Date of Patent: September 28, 2004Assignee: Hewlett-Packard Development Company, L.P.Inventors: David John Marshall, Karl Joseph Bois, David W. Quint
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Publication number: 20040150009Abstract: Buffer that includes an input node, an output node, and a three-transistor charge pump circuit is coupled to the input node and the output node. The buffer generates an output signal that is a delayed version of a signal presented at the input node. The three-transistor charge pump includes a first transistor (e.g., a pass transistor) that includes a drain electrode that is coupled to the input node, a gate electrode and a source electrode; a second transistor that includes a drain electrode that is coupled to a first predetermined voltage, a gate electrode coupled to the drain electrode of the second transistor, and a source electrode coupled to the gate electrode of the first transistor; and a capacitive element that includes a first electrode that is coupled to the source electrode of the second transistor and the gate electrode of the first transistor and a second electrode that is coupled to the output node.Type: ApplicationFiled: January 31, 2003Publication date: August 5, 2004Inventors: David John Marshall, Ian Erickson, Michael H. Cogdill
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Patent number: 6756862Abstract: A six-drop bus has each driver or receiver terminated at the characteristic impedance of Z0. Each driver or receiver is connected to a segment of transmission line with a characteristic impedance of Z0. Three of these segments are connected at a first point. The other three of these segments are connected at a second point. The first and second points are connected by a central transmission line with a characteristic impedance of Z0/3.Type: GrantFiled: June 21, 2002Date of Patent: June 29, 2004Assignee: Hewlett-Packard Development Company, L.P.Inventors: Karl Joseph Bois, David W. Quint, David John Marshall
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Publication number: 20040085088Abstract: A method of enhancing noise margin on digital signal lines of a system includes steps of evaluating impedances and lengths of the digital signal lines. Resonances of each digital signal line are determined, and target waveforms for each digital signal line optimized for noise margin are determined. A configuration is generated for a programmable device driver to configure the device driver to generate the waveform optimized for noise margin. An alternative embodiment selects waveforms, and corresponding configurations, from a group of possible waveforms at boot time to ensure that data is transferred with optimum noise margins. Also claimed is apparatus embodying bus drivers capable of driving a bus with a waveform approximating blended trapezoidal and sinusoidal edge shapes, this waveform being optimum for noise margin in certain systems having multidrop busses.Type: ApplicationFiled: November 5, 2002Publication date: May 6, 2004Inventors: David John Marshall, Philip L. Barnes, Larry Jay Thayer
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Publication number: 20030234702Abstract: A six-drop bus has each driver or receiver terminated at the characteristic impedance of Z0. Each driver or receiver is connected to a segment of transmission line with a characteristic impedance of Z0. Three of these segments are connected at a first point. The other three of these segments are connected at a second point. The first and second points are connected by a central transmission line with a characteristic impedance of Z0/3.Type: ApplicationFiled: June 21, 2002Publication date: December 25, 2003Inventors: Karl Joseph Bois, David W. Quint, David John Marshall
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Publication number: 20030206044Abstract: A reference voltage is moved dynamically towards a voltage level of the last received value. The movement takes place over a predetermined fraction of a bit-time. The amount of movement is limited so that successive logical values don't result in an unusable reference voltage level. When the output of a receiver changes, a state machine sequences the selection of analog reference voltage inputs to a multiplexer to move an output reference voltage towards a steady-state signal voltage level for the value that was just received. When the sequence is complete, the state machine keeps the last value selected on the output until the output of the receiver changes value.Type: ApplicationFiled: May 29, 2003Publication date: November 6, 2003Inventors: David John Marshall, Karl Joseph Bois, David W. Quint
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Patent number: 6624686Abstract: An embodiment of the invention provides a circuit and method for reducing power in dynamic circuits. A large single pre-charge FET is used to pre-charge the pre-charge nodes of all dynamic logic blocks contained in a plurality of dynamic logic blocks. The large single pre-charge FET replaces all smaller individual FETs that normally would be used. Because smaller FETs typically have more subthreshhold leakage than larger FETs, the overall subthreshhold leakage is reduced. The large pre-charge FET only replaces smaller pre-charge FETs that have the same pre-charge signal going to their gates.Type: GrantFiled: July 26, 2002Date of Patent: September 23, 2003Assignee: Hewlett-Packard Development Company, L.P.Inventors: Elias Gedamu, Denise Man, David John Marshall
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Patent number: 5884422Abstract: A plastic garment hanger having a hook with an abutment for engaging an aperture formed in an indicator cap to support the indicator cap on the hanger is provided. A hook having an upwardly projecting web which defines an aperture wherein a descending flexible tongue for engaging an aperture formed in an indicator cap is also provided.Type: GrantFiled: January 10, 1997Date of Patent: March 23, 1999Assignee: Spotless Plastics Pty. Ltd.Inventors: David John Marshall, Joseph Charles Hollis
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Patent number: 5857276Abstract: A plastic garment hanger having a hook with an abutment for engaging an aperture formed in an indicator cap to support the indicator cap on the hanger is provided. A hook having an upwardly projecting web which defines an aperture wherein a descending flexible tongue for engaging an aperture formed in an indicator cap is also provided.Type: GrantFiled: July 31, 1997Date of Patent: January 12, 1999Assignee: Spotless Plastics Pty. Ltd.Inventors: David John Marshall, Stanley Gouldson, Roland Harmer
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Patent number: 5794363Abstract: A plastic garment hanger having a hook with an abutment for engaging an aperture formed in an indicator cap to support the indicator cap on the hanger is provided. A hook having an upwardly projecting web which defines an aperture wherein a descending flexible tongue for engaging an aperture formed in an indicator cap is also provided.Type: GrantFiled: February 6, 1995Date of Patent: August 18, 1998Assignee: Spotless Plastics Pty. Ltd.Inventors: David John Marshall, Stanley Gouldson, Roland Harmer