Patents by Inventor Robert H. Isham
Robert H. Isham 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: 7541797Abstract: A control circuit for a DC voltage supply is provided that includes a circuit, an error amplifier and modulator. The circuit is operable to measure a voltage difference between a negative voltage rail and a ground reference in the DC voltage supply. The circuit is further operative to create an offset voltage proportional with the measured voltage difference. The circuit is further yet operative to add the offset voltage to a reference voltage to create a modified reference voltage. The error amplifier has a first input coupled to receive the modified reference voltage and a second input coupled to a positive voltage rail in the DC voltage supply. The error amplifier further has an output. The modulator is coupled to the output of the error amplifier. The modulator is operative to maintain the positive rail at a select value corresponding to the modified reference voltage.Type: GrantFiled: March 3, 2008Date of Patent: June 2, 2009Assignee: Intersil Americas Inc.Inventors: Noel B. Dequina, Robert H. Isham
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Patent number: 7535211Abstract: A voltage regulator which includes a network for improved compensation for reference voltage changes includes an IC including an error amplifier and a pulse width modulator (PWM), wherein an input of the PWM is coupled to an output of the error amplifier. A low pass filter comprising an inductor is in series with a grounded capacitor coupled to an output of the PWM, wherein an output of the regulator (Vout) is at a node between the inductor and the capacitor. A first feedback network is disposed between Vout and an inverting input of the error amplifier and a second feedback network is disposed between an output of the error amplifier and the inverting input of the error amplifier. A current cancellation network is coupled to the inverting input of the error amplifier.Type: GrantFiled: September 27, 2006Date of Patent: May 19, 2009Assignee: Intersil Americas Inc.Inventor: Robert H. Isham
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Publication number: 20090072807Abstract: An adaptive pulse positioning system for a voltage converter including an adjustable ramp generator, a pulse generator circuit, and a sense and adjust circuit. The adjustable ramp generator has an adjust input and provides a periodic ramp voltage having an adjustable magnitude based on an adjust signal provided to the adjust input. The pulse generator circuit receives the ramp voltage and generates a pulse signal with control pulses for controlling the output voltage of the voltage controller based on the ramp voltage. The sense and adjust circuit senses an output load transient and provides the adjust signal to the adjust input of the ramp generator to adaptively shift the pulse signal in time in response to the output load transient without adding pulses to the pulse signal.Type: ApplicationFiled: November 18, 2008Publication date: March 19, 2009Applicant: Intersil Americans Inc.Inventors: Weihong Qiu, Robert H. Isham, Zhixiang Liang, Thomas Szepesi
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Patent number: 7489121Abstract: A PWM control circuit for a voltage regulator including a compensation network, a ramp generator providing a ramp voltage, an offset adjust circuit and a comparator circuit. The compensation network senses the output voltage, receives a reference voltage, and outputs a compensation voltage. The offset adjust circuit adjusts a selected one of the ramp voltage and the compensation voltage based on the reference voltage. The comparator circuit compares the compensation voltage with the ramp voltage and provides a PWM signal for controlling the output voltage. The offset adjust circuit may generate an offset voltage based on the reference voltage and a gain G of the voltage regulator. The offset adjust circuit may subtract the offset voltage from either the ramp voltage or the compensation voltage to provide an adjusted voltage to the comparator circuit.Type: GrantFiled: March 31, 2006Date of Patent: February 10, 2009Assignee: Intersil Americas Inc.Inventors: Weihong Qiu, Robert H. Isham, Zhixiang Liang
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Patent number: 7453246Abstract: An adaptive pulse positioning system for a voltage converter providing an output voltage, the system including a PWM generation circuit, a sensor, and a pulse positioning circuit. The PWM generation circuit generates a PWM signal with PWM pulses for controlling the output voltage of the voltage controller. The sensor senses an output load condition of the voltage converter and provides a load signal indicative thereof. The pulse positioning circuit adaptively positions the PWM pulses based on the load signal. A method of adaptively positioning PWM pulses that are used to control an output voltage of a voltage regulator including generating a series of PWM pulses based on a clock signal, sensing an output load condition, and adaptively shifting the series of PWM pulses based on the output load condition.Type: GrantFiled: May 17, 2006Date of Patent: November 18, 2008Assignee: Intersil Americas Inc.Inventors: Weihong Qiu, Robert H. Isham, Zhixiang Liang
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Patent number: 7453250Abstract: A dual-edge modulation controller including first and second ramp circuits, first and second comparators, an error amplifier and pulse control logic. The first ramp circuit provides a leading-edge ramp synchronous with a clock. The error amplifier compares a feedback signal with a reference and provides a compensation signal. The first comparator compares the leading-edge ramp with the compensation signal and asserts a set signal. The second ramp circuit provides a trailing-edge ramp that begins ramping when the set signal is asserted. The second comparator compares the trailing-edge ramp with the compensation signal and asserts a reset signal. The pulse control logic asserts a PWM signal when the set signal is asserted and de-asserts the PWM signal when the reset signal is asserted. The controller may control multiple phases with current balancing. The slew rate of the ramps may be adjusted based on the number of PWM signal asserted.Type: GrantFiled: December 23, 2005Date of Patent: November 18, 2008Assignee: Intersil Americas Inc.Inventors: Weihong Qiu, Zhixiang Liang, Robert H. Isham, Ben A. Dowlat, Rami Abou-Hamze
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Publication number: 20080272752Abstract: A multiphase regulator which includes an output node developing an output voltage, a feedback circuit determining error of the output voltage and providing a compensation signal indicative thereof, at least three phase circuits coupled in parallel to the output node, and an adaptive controller. Each phase circuit includes a modulation circuit and a switch circuit. Each modulation circuit receives the compensation signal and generates pulses on a corresponding one of the pulse modulation signals. Each switch circuit is coupled to the output node and is controlled by a corresponding pulse modulation signal. The adaptive controller is responsive to a load indication signal, such as indicating a low load condition, and drops operation of at least one of the phase circuits and adds at least one pulse to a pulse modulation signal of each remaining phase circuit.Type: ApplicationFiled: December 12, 2007Publication date: November 6, 2008Applicant: INTERSIL AMERICAS INC.Inventors: Weihong Qiu, Robert H. Isham, Chun Cheung
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Publication number: 20080197824Abstract: A pulse width modulation (PWM) modulator for a multiphase power converter and related adaptive firing order (AFO) method includes a multiphase leading edge generator having pulse generating circuitry associated with each of the regulator phases, wherein the pulse generating circuitry generates phase pulses associated with each of the phases. An adaptive firing order (AFO) controller having circuitry including a mixer receives and sums the phase pulses into a summing signal and uses the summing signal to generate a series of turn-on pulses therefrom. A multiphase PWM generator has inputs coupled to an output of the AFO controller coupled to receive the series of turn-on pulses, the multiphase PWM generator having circuitry for generating said PWM signals therefrom. An adaptive firing order (AFO) controlled multi-phase power converter includes a plurality of parallel connected regulator phases controlled by respective pulse width modulation (PWM) signals provided by the PWM modulator.Type: ApplicationFiled: March 30, 2007Publication date: August 21, 2008Inventors: Weihong Qiu, Shangyang Xiao, Robert H. Isham
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Patent number: 7345463Abstract: A load compensated voltage regulator comprises a chip including a control section having an error amplifier, a pulse width modulator (PWM), the PWM outputting at least one driver control signal. At least one driver has an input coupled to receive the driver control signal. An output stage includes at least one output transistor having an input coupled to an output of the driver. The output transistor drives an inductor in series with a grounded capacitor, wherein an output of the regulator (VOUT) is at a node between the inductor and the capacitor, wherein VOUT generates a load current across a load when connected across the capacitor. A feedback connector is provided for feeding back a feedback signal representative of the load current to circuitry for outputting a gate driver voltage supply control signal based on at least reference level and the feedback signal. A connector couples at least one power supply to the driver through a switch or a second regulator.Type: GrantFiled: November 7, 2006Date of Patent: March 18, 2008Assignee: Intersil Americas Inc.Inventor: Robert H. Isham
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Publication number: 20080007241Abstract: A load compensated voltage regulator comprises a chip including a control section having an error amplifier, a pulse width modulator (PWM), the PWM outputting at least one driver control signal. At least one driver has an input coupled to receive the driver control signal. An output stage includes at least one output transistor having an input coupled to an output of the driver. The output transistor drives an inductor in series with a grounded capacitor, wherein an output of the regulator (VOUT) is at a node between the inductor and the capacitor, wherein VOUT generates a load current across a load when connected across the capacitor. A feedback connector is provided for feeding back a feedback signal representative of the load current to circuitry for outputting a gate driver voltage supply control signal based on at least reference level and the feedback signal. A connector couples at least one power supply to the driver through a switch or a second regulator.Type: ApplicationFiled: November 7, 2006Publication date: January 10, 2008Applicant: INTERSIL AMERICAS INC.Inventor: Robert H. Isham
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Publication number: 20070273348Abstract: A voltage regulator which includes a network for improved compensation for reference voltage changes includes an IC including an error amplifier and a pulse width modulator (PWM), wherein an input of the PWM is coupled to an output of the error amplifier. A low pass filter comprising an inductor is in series with a grounded capacitor coupled to an output of the PWM, wherein an output of the regulator (Vout) is at a node between the inductor and the capacitor. A first feedback network is disposed between Vout and an inverting input of the error amplifier and a second feedback network is disposed between an output of the error amplifier and the inverting input of the error amplifier. A current cancellation network is coupled to the inverting input of the error amplifier.Type: ApplicationFiled: September 27, 2006Publication date: November 29, 2007Applicant: INTERSIL AMERICAS INC.Inventor: Robert H. Isham
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Publication number: 20070274015Abstract: A DC-DC converter includes a chip including an error amplifier and a pulse width modulator (PWM) having an input connected to an output of the error amplifier, and an inductor driven by said PWM in series with an output node (VOUT) of the converter, wherein a load current flows through the inductor. VOUT is fed back through a network including a feedback resistor (RFB) to an inverting input of the error amplifier. A circuit for sensing the load current includes a first operational amplifier, a sense resistor on the chip having resistance RSENSE coupled to an inverting input of the first amplifier; wherein a sense current related to the load current flows through the sense resistor, a dependent current source provides an output current to supply the sense current. A reference resistor is disposed on the chip having a resistance RREFERENCE which is a fixed multiple of RSENSE. A set resistor is provided having a resistance RSET.Type: ApplicationFiled: September 27, 2006Publication date: November 29, 2007Applicant: INTERSIL AMERICAS INC.Inventor: Robert H. Isham
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Patent number: 7088151Abstract: A multi-level current pulse generator for driving the gates of a CMOS pair implemented using a low voltage process including a multi-level pulse translator, a current amplifier circuit, and a clamp circuit. The multi-level pulse translator generates a multi-level current pulse on at least one pulse node, each current pulse having a first large current pulse with short duration followed by at least one smaller current pulse of longer duration and operative to switch the CMOS pair with reduced average power dissipation. The current amplifier circuit amplifies the current pulses provided to the gates of the CMOS pair. The clamp circuit clamps gate voltage of the CMOS pair to prevent breakdown. In a tri-level case, a first current pulse charges and discharges gate capacitance, a second current pulse stabilizes gate voltage, and a third current pulse provides a holding current level.Type: GrantFiled: April 21, 2004Date of Patent: August 8, 2006Assignee: Intersil Americas Inc.Inventors: Noel B. Dequina, Robert H. Isham, Paul K. Sferrazza, Donald R. Preslar
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Patent number: 6977489Abstract: A controller for a multiphase converter including an error amplifier, a gain resistor, a current sense circuit and a gain adjust amplifier. The error amplifier generates an error signal based on an error voltage developed across a feedback resistance. The current sense circuit converts each of multiple sensed load currents into corresponding proportional voltages. The gain adjust amplifier circuit receives the proportional voltages and operates to apply at least one gain adjust voltage to the gain resistor to develop a gain adjust current that is applied through the feedback resistance to adjust gain. In one embodiment, the proportional voltages are time multiplexed or averaged to provide the gain adjust voltage(s). An IC integrating the multiphase converter need only include a single gain pin for coupling to a gain resistor to set gain for each phase.Type: GrantFiled: November 5, 2003Date of Patent: December 20, 2005Assignee: Intersil Americas, IncInventor: Robert H. Isham
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Patent number: 6975261Abstract: A D/A converter including first and second R-R2 resistor ladders and a set of SPDT switches. The first R-2R resistor ladder includes N type resistors coupled between a common voltage node and an output voltage node and the second R-2R resistor ladder includes P type resistors coupled between the common and output voltage nodes. The R-2R resistor ladders have multiple common switch terminals, each coupling an N type 2R resistor to a corresponding P type 2R resistor. Each SPDT switch is responsive to a data bit for switching a common switch terminal between the common voltage and a reference voltage. Each N type resistor may be formed in a PWell coupled to the common (or more negative) voltage and each P type resistor may be formed in an NWell coupled to the reference (or more positive) voltage. The SPDT switches may be configured with equivalent switch path impedances.Type: GrantFiled: November 15, 2004Date of Patent: December 13, 2005Assignee: Intersil America's Inc.Inventor: Robert H. Isham
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Patent number: RE38780Abstract: A DC/DC converter has an output voltage and sources an output current to a load. The DC/DC converter includes an error amplifier with a reference input and a summing input. The reference input is electrically connected to a reference voltage. The summing input is electrically connected to the output voltage and the output current. The summing input is configured for adding together the output voltage and the output current. The error amplifier issues an error signal and adjusts the error signal dependent at least in part upon the output voltage and the output current. A comparator receives the error signal. The comparator has a ramp input electrically connected to a voltage ramp signal. The comparator issues an output signal that is based at least in part upon said error input. A power switch has an on condition and an off condition, and supplies dc current to the load when in the on condition. The power switch has a control input electrically connected to the comparator output signal.Type: GrantFiled: February 26, 2003Date of Patent: August 23, 2005Assignee: Intersil Americas Inc.Inventors: Charles E. Hawkes, Michael M. Walters, Robert H. Isham
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Patent number: RE38846Abstract: A multi-phase DC/DC converter having an output voltage and including a plurality of converter channels. Each converter channel includes a converter channel input and a converter channel output. Each converter channel is configured for generating a converter channel current and for adjusting said converter channel current in response to a control signal electrically connected to each converter channel input. A control circuit generates an error signal representative of a comparison of the converter output voltage to a reference voltage. The control circuit includes a plurality of control circuit channels, each of which correspond to a converter channel. Each control circuit channel generates a channel current signal representative of a corresponding converter channel current, and generates a differential channel current signal representative of a comparison of the channel current signal to an average current signal.Type: GrantFiled: February 26, 2003Date of Patent: October 25, 2005Assignee: Intersil Communications, Inc.Inventors: Michael M. Walters, Charles E. Hawkes, Robert H. Isham
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Patent number: RE38906Abstract: A DC/DC converter has an output voltage and sources an output current to a load. The DC/DC converter includes an error amplifier with a reference input and a summing input. The reference input is electrically connected to a reference voltage. The summing input is electrically connected to the output voltage and the output current. The summing input is configured for adding together the output voltage and the output current. The error amplifier issues an error signal and adjusts the error signal dependent at least in part upon the output voltage and the output current. A comparator receives the error signal. The comparator has a ramp input electrically connected to a voltage ramp signal. The comparator issues an output signal that is based at least in part upon said error input. A power switch has an on condition and an off condition, and supplies dc current to the load when in the on condition. The power switch has a control input electrically connected to the comparator output signal.Type: GrantFiled: January 11, 2002Date of Patent: December 6, 2005Assignee: Intersil Americas, Inc.Inventors: Charles E. Hawkes, Michael M. Walters, Robert H. Isham
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Patent number: RE38940Abstract: A DC to DC buck pulse width modulator converter circuit includes an input, a high side output and a low side output. A high side switch is electrically connected between a common output node and a voltage supply, and controls a flow of current therethrough dependent upon the high side output. A low side switch is electrically connected between the common output node and ground, and controls a flow of current therethrough dependent upon the low side output. A virtual ground amplifier includes a second input electrically connected to ground. A current feedback resistor is electrically connected intermediate the common output node and a first input of the virtual ground amplifier. A variable impedance component is electrically connected to an output of the virtual ground amplifier and to the first input of the virtual ground amplifier. The impedance of the variable impedance component is varied dependent upon the output of the virtual ground amplifier.Type: GrantFiled: October 29, 2002Date of Patent: January 24, 2006Assignee: Intersil Communications, Inc.Inventors: Robert H. Isham, Charles E. Hawkes, Michael M. Walters
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Patent number: RE40593Abstract: A multi-phase DC/DC converter having an output voltage and including a plurality of converter channels. Each converter channel includes a converter channel input and a converter channel output. Each converter channel is configured for generating a converter channel current and for adjusting said converter channel current in response to a control signal electrically connected to each converter channel input. A control circuit generates an error signal representative of a comparison of the converter output voltage to a reference voltage. The control circuit includes a plurality of control circuit channels, each of which correspond to a converter channel. Each control circuit channel generates a channel current signal representative of a corresponding converter channel current, and generates a differential channel current signal representative of a comparison of the channel current signal to an average current signal.Type: GrantFiled: October 24, 2005Date of Patent: December 2, 2008Assignee: Intersil Americas Inc.Inventors: Michael M. Walters, Charles E. Hawkes, Robert H. Isham