International Business Machines Corporation

Chandler Todd McDowell

Uttam Shymalindu Ghoshal

Wendy Ann Belluomini

Robert K Montoye

Sani Richard Nassif

Steven Alan Cordes

James Patrick Doyle

Matthew J Farinelli

Li Shi

David R DiMilia

Snigdha Ghoshal

Ying Liu

Hung Cai Ngo

Andrew Kenneth Martin

Kanak Behari Agarwal

Peilin Song

Franco Stellari

Stanislav Polonsky

Alan Weger

Jayakumaran Sivagnaname

Ramyanshu Datta

James F Plusquellic

Jente Benedict Kuang

Gary Dale Carpenter

Jun Sawada

Alan J Drake

Fadi Hikmat Gebara

A circuit and method of correcting the duty cycle of digital signals is disclosed. The duty cycle of an input digital signal is measured and compared to a desired duty cycle. The leading edge of the input digital signal is passed to an output. The circuit and method adjust the falling edges at the output to achieve the desired duty cycle. The falling edges occur in response to rising edges of a delayed version of the input digital signal.

Digital duty cycle corrector

A test structure for statistical characterization of local device mismatches contains densely populated SRAM devices arranged in a row/column addressable array that enables resource sharing of many devices. The test structure includes a built-in sensing mechanism to calibrate or null out sources of error, and current steering to avoid negative effects of current leakage along spurious paths. The gate and drain lines of each column are driven from both the top and bottom to minimizes parasitic effects. The system can handle a large number of devices while still providing high spatial resolution of current measurements.

Method and apparatus for measuring device mismatches

Methods and arrangements to enhance photon emissions responsive to a signal within an integrated circuit (IC) for observability of signal states utilizing, e.g., picosecond imaging circuit analysis (PICA), are disclosed. Embodiments attach a beacon to the signal of interest and apply a voltage across the beacon to enhance photon emissions responsive to the signal of interest. The voltage is greater than the operable circuit voltage, Vdd, to enhance photon emissions with respect to intensity and energy. Thus, the photon emissions are more distinguishable from noise. In many embodiments, the beacon includes a transistor and, in several embodiments, the beacon includes an enablement device to enable and disable photon emissions from the beacon. Further, a PICA detector may capture photon emissions from the beacon and process the photons to generate time traces.

Enhanced signal observability for circuit analysis

A method and system for scanning data from a specific latch in a matrix array of latches. The matrix array is made up of vertical selector lines and horizontal data lines. Each latch is coupled at an intersection of a selector line and a data line by a transistor. By turning on the transistor, the contents of the latch can be selectively read or written to.

Scanning latches using selecting array

A 4-to-2 carry save adder using limited switching dynamic logic (LSDL) to reduce power consumption while reducing the delay of outputting the sum and carry bits. The 4-to-2 carry save adder may include a first LSDL circuit configured to output a sum bit. The carry save adder may further include a second LSDL circuit configured to output a carry bit. Both the first and second LSDL circuits use a carry generated in the current stage that was previously generated in the previous stage (next lower order bit position). Since the carry is generated in the current stage and not in the previous stage, the delay in outputting the sum and carry bits is reduced and hence the performance of carry save adders is improved. Further, since LSDL circuits were used in the carry save adder, power consumption was reduced while using a small amount of area.

4-to-2 carry save adder using limited switching dynamic logic

A 4-to-2 carry save adder with a reduction in the delay of outputting the sum and carry bits. The 4-to-2 carry save adder may include a lower order full order coupled to a higher order full adder. The carry save adder may further include a logic unit coupled to the higher order full adder where the logic unit is configured to generate a carry bit to be inputted to the higher order full adder that normally would be generated from the carry save adder located in the previous stage. By generating this carry bit (carry-in bit) in the current stage and not in the previous stage, the delay of the carry-in bit inputted to the higher order full adder is reduced thereby reducing the delay of outputting the sum and carry bits by the higher order full adder.

Computing carry-in bit to most significant bit carry save adder in current stage

A method and system for manipulating data in a state holding elements array. Process data is moved through the state holding elements array by a process controller. A separate scan controller scans data out of the state holding elements array by scanning data out of a group of cascaded latches where there are insufficient extra state holding elements in the group to enable normal scan. A multiplicity of local scan clocks are utilized to shift selected amounts of data only when a next state holding element in the group has been made available by clearing the contents of that next state holding element. In this way, any given latch, for the purpose of scan, is not a dedicated master or slave latch, but can act as either. This invention also addresses a circuit for the creation of the multiplicity of local clocks from a conventional LSSD clock source.

Method and apparatus for low overhead circuit scan

A method and ring oscillator circuit for measuring circuit delays over a wide operating range permits improved analysis of dynamic circuits. A pulse generator circuit provides a pulse to an input of a dynamic circuit under test, which may be a pre-charge or evaluation pulse that is triggered by a transition of an output of the dynamic circuit that occurs during the state opposite that of the state commanded by the pulse. The action of the circuit provides for measuring any amount of delay to the next transition in the opposite state irrespective of the pulse width. By providing a wide-range of operation, characteristics such as leakage, charge sharing, data dependent node capacitance, previous value dependence as well as other dynamic circuit behaviors may be determined. The ring oscillator circuit includes an enable start circuit that causes a first pulse to be generated by the one-shot when the ring oscillator circuit is enabled.

Method and ring oscillator circuit for measuring circuit delays over a wide operating range

A scanning heat flow probe for making quantitative measurements of heat flow through a device under test is provided. In one embodiment the scanning heat flow probe includes an electric current conductor in a cantilever beam connected to a probe tip and coupled to two voltmeter leads. The probe also includes two thermocouple junctions in the cantilever beam electrically isolated from the electric current conductor and the two voltmeter leads. Heat flow is derived quantitatively using only voltage and current measurements. In other forms, the invention relates to the calibration of scanning heat flow probes through a method involving interconnected probes, and relates to the minimization of heat flow measurement uncertainty by probe structure design practices.

Scanning heat flow probe

A method and systems for projecting an image onto a screen in high ambient light. The image is composed as pixels comprising selected intensities of preselected bands of visible light. The pixels are created by modulating three frequencies of light corresponding to hues in the red, green, and blue spectrum. The modulated light selectively generates pixels of a frame of the image. A diffusive projection screen has a triple bandpass light filter surface that selectively transmits preselected bands of light frequencies around the red, green, and blue spectrums of the modulated light source. The triple bandpass light filter is used with projection screens in front and rear projection systems. The hues of red, green, and blue may be generated from LEDs or from extracting the frequencies from a broadband source. The modulator system may comprise a time multiplexed single modulator design or a triple modulator design.

Ambient light tolerant image projection method and system

Power consumption is reduced for power supplied by a voltage adapter, such as an AC/DC adapter. A power source is connected to a power unit, including the voltage adapter and control circuitry. The voltage adapter supplies power to a load, such as a computer system. A load current supplied by the voltage adapter and an output voltage of the voltage adapter are measured by the control circuitry, and a control device of the control circuitry selectively disconnects the voltage adapter from the power source. The disconnecting is responsive to the control circuitry inferring from the measured current and voltage that the load is turned off, or at least operating in a reduced power consumption mode.

Method and apparatus for reducing power consumption for power supplied by a voltage adapter

An apparatus for measuring capacitance of a semiconductor device is disclosed. The apparatus includes a signal source circuit, a first transistor, a second transistor, and bypass capacitor. The first transistor is connected in series with the second transistor, and the second transistor is connected in series with a device under test. The bypass capacitor connected in parallel with the first and second transistors. Coupled to the first and second transistors, the signal source circuit generates a first signal and a second signal to alternately turn on said first and second transistors such that a discharge current is generated to flow through the first and second transistors.

Growing community of inventors

Austin, TX, United States of America

Chandler Todd McDowell