Patents by Inventor Rahul M. Rao
Rahul M. Rao 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: 8966420Abstract: A method for estimating delay deterioration in an integrated circuit comprising estimating degradation in at least one characteristic of each device defined within the integrated circuit using voltages and logic values monitored during a simulation of the digital circuit. Generating an end-of-life netlist in which the at least one device characteristic of each device has been modified to reflect the estimated degradation or estimating a change in timing delay of each device directly from the estimated degradation of the at least one characteristic of each device. A timing analysis is performed using the estimated change in timing delay of each device to determine circuit path delays. The timing analysis is static or statistical.Type: GrantFiled: September 12, 2012Date of Patent: February 24, 2015Assignee: International Business Machines CorporationInventors: Aditya Bansal, Jae-Joon Kim, Rahul M. Rao
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Publication number: 20130258750Abstract: A dual-cell spin-transfer torque random-access memory including a first magnetic tunneling junction and a second magnetic tunneling junction. An access circuit is coupled to the first and second magnetic tunneling junctions such that independent read and write access is provided to bits stored in the first and second magnetic tunneling junctions.Type: ApplicationFiled: March 30, 2012Publication date: October 3, 2013Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATIONInventors: JAE-JOON KIM, RAHUL M. RAO
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Publication number: 20130254731Abstract: A method for estimating delay deterioration in an integrated circuit comprising estimating degradation in at least one characteristic of each device defined within the integrated circuit using voltages and logic values monitored during a simulation of the digital circuit. Generating an end-of-life netlist in which the at least one device characteristic of each device has been modified to reflect the estimated degradation or estimating a change in timing delay of each device directly from the estimated degradation of the at least one characteristic of each device. A timing analysis is performed using the estimated change in timing delay of each device to determine circuit path delays. The timing analysis is static or statistical.Type: ApplicationFiled: September 12, 2012Publication date: September 26, 2013Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATIONInventors: Aditya Bansal, Jae-Joon Kim, Rahul M. Rao
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Publication number: 20130253868Abstract: A method for estimating delay deterioration in an integrated circuit comprising estimating degradation in at least one characteristic of each device defined within the integrated circuit using voltages and logic values monitored during a simulation of the digital circuit. Generating an end-of-life netlist in which the at least one device characteristic of each device has been modified to reflect the estimated degradation or estimating a change in timing delay of each device directly from the estimated degradation of the at least one characteristic of each device. Performing a timing analysis using the estimated change in timing delay of each device to determine circuit path delays. The timing analysis being static or statistical.Type: ApplicationFiled: March 23, 2012Publication date: September 26, 2013Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATIONInventors: ADITYA BANSAL, Jae-Joon Kim, Rahul M. Rao
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Patent number: 8526219Abstract: A memory circuit includes a plurality of bit line structures (each including a true and a complementary bit line), a plurality of word line structures intersecting the plurality of bit line structures to form a plurality of cell locations; and a plurality of cells located at the plurality of cell locations. Each of the cells includes a logical storage element, a first access transistor selectively coupling a given one of the true bit lines to the logical storage element, and a second access transistor selectively coupling a corresponding given one of the complementary bit lines to the logical storage element. One or both of the first and second access transistors are configured with asymmetric current characteristics to enable independent enhancement of READ and WRITE margins. Also included within the 6-T scope are one or more design structures embodied in a machine readable medium, comprising circuits as set forth herein.Type: GrantFiled: February 7, 2012Date of Patent: September 3, 2013Assignee: International Business Machines CorporationInventors: Aditya Bansal, Ching-Te K. Chuang, Jae-Joon Kim, Shih-Hsien Lo, Rahul M. Rao
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Patent number: 8493774Abstract: A circuit structure is provided for performing a logic function within a memory. A plurality of read word line transistors are provided that receive a read word line signal and, upon receiving the read word line signal, the plurality of read word line transistors provide a path from a plurality of bit-line transistors associated with a plurality of physically adjacent memory cells to a read bit-line. In response to an associated memory cell within the memory storing a first value, each of the plurality of read bit-line transistors turns on and provides a path to ground thereby causing a first output value to be output on the read bit-line. In response to all of the plurality of memory cells storing a second value, the plurality of read bit-line transistors turn off thereby preventing a path to ground and a second output value is output on the read bit-line.Type: GrantFiled: June 17, 2011Date of Patent: July 23, 2013Assignee: International Business Machines CorporationInventors: Jente B. Kuang, Rahul M. Rao
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Patent number: 8456247Abstract: A ring oscillator circuit for measurement of negative bias temperature instability effect and/or positive bias temperature instability effect includes a ring oscillator having first and second rails, and an odd number (at least 3) of repeating circuit structures. Each of the repeating circuit structures in turn includes an input terminal and an output terminal; a first p-type transistor having a gate, a first drain-source terminal coupled to the first rail, and a second drain source terminal selectively coupled to the output terminal; a first n-type transistor having a gate, a first drain-source terminal coupled to the second rail, and a second drain source terminal selectively coupled to the output terminal; and repeating-circuit-structure control circuitry. The ring oscillator circuit also includes a voltage supply and control block.Type: GrantFiled: January 19, 2011Date of Patent: June 4, 2013Assignee: International Business Machines CorporationInventors: Jae-Joon Kim, Rahul M. Rao
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Publication number: 20130138407Abstract: Methods and systems for computing threshold voltage degradation of transistors in an array of memory cells are disclosed. In accordance with one method, a process that models an expected usage of the array is selected. In addition, a hardware processor can run the process to populate the array with data over time to simulate the expected usage of the array. The method further includes compiling data that detail different durations at which each of the memory cells in the array stores 1 or at which each of the memory cells in the array stores 0. For each separate grouping of memory cells that share a common duration of the different compiled durations, a threshold voltage degradation is determined for each transistor in the corresponding grouping of cells based on at least one biased temperature instability model.Type: ApplicationFiled: September 13, 2012Publication date: May 30, 2013Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATIONInventors: Aditya Bansal, Jae-Joon Kim, Rahul M. Rao
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Publication number: 20130138403Abstract: Methods and systems for computing threshold voltage degradation of transistors in an array of memory cells are disclosed. In accordance with one method, a process that models an expected usage of the array is selected. In addition, a hardware processor can run the process to populate the array with data over time to simulate the expected usage of the array. The method further includes compiling data that detail different durations at which each of the memory cells in the array stores 1 or at which each of the memory cells in the array stores 0. For each separate grouping of memory cells that share a common duration of the different compiled durations, a threshold voltage degradation is determined for each transistor in the corresponding grouping of cells based on at least one biased temperature instability model.Type: ApplicationFiled: November 29, 2011Publication date: May 30, 2013Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATIONInventors: Aditya Bansal, Jae-Joon Kim, Rahul M. Rao
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Publication number: 20130049791Abstract: A delay is measured through an array of transistors by selecting one transistor in the array; and applying a clock signal to the selected transistor. An output of the selected transistor is applied to a first input of a logic gate and a second clock signal based on the clock signal is applied to a second input of the logic gate. An output of the logic gate indicates a difference in arrival times of the signals at the two inputs. A clock signal can be applied to the selected transistor and a variable delay circuit. An output of the selected transistor is applied to a data input of a latch while an output of the variable delay circuit is applied to a clock input of the latch. The delay applied by the variable delay circuit is adjusted until a predefined transition is detected. The delay variation among the transistors can be obtained.Type: ApplicationFiled: August 31, 2012Publication date: February 28, 2013Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATIONInventors: Keith A. Jenkins, Jae-Joon Kim, Rahul M. Rao
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Publication number: 20120320689Abstract: A circuit structure is provided for performing a logic function within a memory. A plurality of read word line transistors are provided that receive a read word line signal and, upon receiving the read word line signal, the plurality of read word line transistors provide a path from a plurality of bit-line transistors associated with a plurality of physically adjacent memory cells to a read bit-line. In response to an associated memory cell within the memory storing a first value, each of the plurality of read bit-line transistors turns on and provides a path to ground thereby causing a first output value to be output on the read bit-line. In response to all of the plurality of memory cells storing a second value, the plurality of read bit-line transistors turn off thereby preventing a path to ground and a second output value is output on the read bit-line.Type: ApplicationFiled: June 17, 2011Publication date: December 20, 2012Applicant: International Business Machines CorporationInventors: Jente B. Kuang, Rahul M. Rao
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Publication number: 20120185817Abstract: A memory circuit includes a plurality of bit line structures (each including a true and a complementary bit line), a plurality of word line structures intersecting the plurality of bit line structures to form a plurality of cell locations; and a plurality of cells located at the plurality of cell locations. Each of the cells includes a logical storage element, a first access transistor selectively coupling a given one of the true bit lines to the logical storage element, and a second access transistor selectively coupling a corresponding given one of the complementary bit lines to the logical storage element. One or both of the first and second access transistors are configured with asymmetric current characteristics to enable independent enhancement of READ and WRITE margins. Also included within the 6-T scope are one or more design structures embodied in a machine readable medium, comprising circuits as set forth herein.Type: ApplicationFiled: February 7, 2012Publication date: July 19, 2012Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATIONInventors: Aditya Bansal, Ching-Te K. Chuang, Jae-Joon Kim, Shih-Hsien Lo, Rahul M. Rao
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Publication number: 20120182079Abstract: A ring oscillator circuit for measurement of negative bias temperature instability effect and/or positive bias temperature instability effect includes a ring oscillator having first and second rails, and an odd number (at least 3) of repeating circuit structures. Each of the repeating circuit structures in turn includes an input terminal and an output terminal; a first p-type transistor having a gate, a first drain-source terminal coupled to the first rail, and a second drain source terminal selectively coupled to the output terminal; a first n-type transistor having a gate, a first drain-source terminal coupled to the second rail, and a second drain source terminal selectively coupled to the output terminal; and repeating-circuit-structure control circuitry. The ring oscillator circuit also includes a voltage supply and control block.Type: ApplicationFiled: January 19, 2011Publication date: July 19, 2012Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATIONInventors: Jae-Joon Kim, Rahul M. Rao
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Publication number: 20120081141Abstract: Methods and apparatus are provided for measuring a delay through one or more transistors in an array of transistors. The delay through one or more transistors in an array of transistors is measured by selecting one of the transistors in the array; and applying a clock signal to the selected transistor, wherein an output of the selected transistor is applied to a first input of a logic gate having at least two inputs and wherein a second clock signal based on the clock signal is applied to a second input of the logic gate, and wherein an output of the logic gate indicates a difference in arrival times of the signals at the two inputs. In one variation, a clock signal is applied to the selected transistor and a variable delay circuit; and an output of the selected transistor is applied to a data input of a latch having a clock input and a data input while an output of the variable delay circuit is applied to a clock input of the latch.Type: ApplicationFiled: September 30, 2010Publication date: April 5, 2012Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATIONInventors: Keith A. Jenkins, Jae-Joon Kim, Rahul M. Rao
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Patent number: 8139400Abstract: A memory circuit includes a plurality of bit line structures (each including a true and a complementary bit line), a plurality of word line structures intersecting the plurality of bit line structures to form a plurality of cell locations and a plurality of cells located at the plurality of cell locations. Each of the cells includes a logical storage element, a first access transistor selectively coupling a given one of the true bit lines to the logical storage element, and a second access transistor selectively coupling a corresponding given one of the complementary bit lines to the logical storage element. One or both of the first and second access transistors are configured with asymmetric current characteristics to enable independent enhancement of READ and WRITE margins. Also included within the 6-T scope are one or more design structures embodied in a machine readable medium, comprising circuits as set forth herein.Type: GrantFiled: January 22, 2008Date of Patent: March 20, 2012Assignee: International Business Machines CorporationInventors: Aditya Bansal, Ching-Te K. Chuang, Jae-Joon Kim, Shih-Hsien Lo, Rahul M. Rao
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Patent number: 8004305Abstract: An electronic circuit includes an output terminal and at least a first measuring FET. The second drain-source terminals of a plurality of FETS to be tested are interconnected with the first drain-source terminal of the first measuring FET and the output terminal. The second drain-source terminal of the first measuring FET is interconnected with a first biasing terminal. The first drain-source terminals of the FETS to be tested are interconnected with a second biasing terminal. A state machine is coupled to the gates of the FETS to be tested and the gate of the first measuring FET. The state machine is configured to energize the gate of the first measuring FET and to sequentially energize the gates of the FETS to be tested, so that an output voltage appears on the output terminal. Circuitry to compare the output voltage to a reference value is also provided.Type: GrantFiled: August 17, 2009Date of Patent: August 23, 2011Assignee: International Business Machines CorporationInventors: Keith A. Jenkins, Jae-Joon Kim, Rahul M. Rao
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Patent number: 7882370Abstract: A static pulse bus circuit and method having dynamic power supply rail selection reduces static and dynamic power consumption over that of static pulse bus designs with fixed power supply rail voltages. Every other (even) bus repeater is operated with a selectable power supply rail voltage that is selected in conformity with a state of the input signal of the bus repeater. The odd bus repeaters are operated from the lower of the selectable power supply voltages supplied to the even repeaters. The odd bus repeaters may also be operated from a selectable power supply rail voltage opposite the selectable-voltage power supply rail provided to the even bus repeaters, in which case the opposing rail of the even bus repeaters is set to the higher of the voltages selectable in the odd bus repeaters.Type: GrantFiled: September 1, 2006Date of Patent: February 1, 2011Assignee: International Business Machines CorporationInventors: Harmander Singh Deogun, Kevin J. Nowka, Rahul M. Rao, Robert M. Senger
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Patent number: 7764080Abstract: An electronic circuit includes an output terminal and at least a first measuring FET. The second drain-source terminals of a plurality of FETS to be tested are interconnected with the first drain-source terminal of the first measuring FET and the output terminal. The second drain-source terminal of the first measuring FET is interconnected with a first biasing terminal. The first drain-source terminals of the FETS to be tested are interconnected with a second biasing terminal. A state machine is coupled to the gates of the FETS to be tested and the gate of the first measuring FET. The state machine is configured to energize the gate of the first measuring FET and to sequentially energize the gates of the FETS to be tested, so that an output voltage appears on the output terminal. Circuitry to compare the output voltage to a reference value is also provided.Type: GrantFiled: August 28, 2008Date of Patent: July 27, 2010Assignee: International Business Machines CorporationInventors: Keith A. Jenkins, Jae-Joon Kim, Rahul M. Rao
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Patent number: 7746709Abstract: In a memory circuit, data from all cells along a selected word line is read. Then, the read data is written back to half-selected cells and new data is written to the selected cells in the next cycle. In cases where a READ bit line (RBL) and WRITE bit line (WBL) are decoupled, RBL and WBL can be accessed simultaneously. Hence, the WRITE in the n-th cycle can be delayed to the n+1-th cycle as far as there is no data hazard such as reading data from memory before correct data are actually written to memory. As a result, there is no bandwidth loss, although the latency of the WRITE operation increases. WRITE stability issues in previous configurations with decoupled RBL and WBL are thus addressed.Type: GrantFiled: December 5, 2008Date of Patent: June 29, 2010Assignee: International Business Machines CorporationInventors: Rajiv V. Joshi, Jae-Joon Kim, Rahul M. Rao
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Patent number: 7642864Abstract: A ring oscillator has an odd number of NOR-gates greater than or equal to three, each with first and second input terminals, a voltage supply terminal, and an output terminal. The first input terminals of all the NOR-gates are interconnected, and each of the NOR-gates has its output terminal connected to the second input terminal of an immediately adjacent one of the NOR-gates. During a stress mode, a voltage supply and control block applies a stress enable signal to the interconnected first input terminals, and an increased supply voltage to the voltage supply terminals. During a measurement mode, this block grounds the interconnected first input terminals, and applies a normal supply voltage to the voltage supply terminals.Type: GrantFiled: January 29, 2008Date of Patent: January 5, 2010Assignee: International Business Machines CorporationInventors: Ching-Te K. Chuang, Jae-Joon Kim, Tae-Hyoung Kim, Pong-Fei Lu, Saibal Mukhopadhyay, Rahul M. Rao, Shao-yi Wang