International Business Machines Corporation

Kevin John Nowka

Hung Cai Ngo

Jente Benedict Kuang

Sang Hoo Dhong

Gary Dale Carpenter

David William Boerstler

Juan-Antonio Carballo

Harm Peter Hofstee

Ivan Vo

Jeffrey L Burns

Ching-Te Kent Chuang

Keunwoo Kim

Robert K Montoye

Joel Abraham Silberman

Liang-Teck Pang

Jerry C Kao

Seung-moon Yoo

Rahul M Rao

Ohsang Kwon

Leland Chang

Michael Jay Shapiro

Brian King Flachs

Seung-Moon Yoo

Nobuo Kojima

Jayakumaran Sivagnaname

Harmander Singh Deogun

Steven Douglas Posluszny

Kyung Tek Lee

Edward J Nowak

Rajiv V Joshi

Kerry Bernstein

Kanak Behari Agarwal

Stephen Victor Kosonocky

Jieming Qi

Norman Jay Rohrer

Jun Sawada

Uttam Shymalindu Ghoshal

Alan J Drake

Fadi Hikmat Gebara

David Meltzer

Damir Anthony Jamsek

Elad Alon

Thomas W Keller, Jr

Mark A Johnson

Bishop Chapman Brock

Robert Matthew Senger

Huajun Wen

Francis H Chan

Peter Edwin Cottrell

H Peter Hofstee

Li Shi

Jethro C Law

Hongfei Wu

Lei Chen

Methods and apparatus are provided for varying one or more of a supply voltage and reference voltage in an integrated circuit, using independent control of a diode voltage in an asymmetrical double-gate device. An integrated circuit is provided that is controlled by one or more of a supply voltage and a reference voltage. The integrated circuit comprises an independently controlled asymmetrical double-gate device to adjust one or more of the supply voltage and the reference voltage. The independent control may comprise, for example, a back gate bias. The independently controlled asymmetrical double-gate device may be employed in a number of applications, including voltage islands, static RAM, and to improve the power and performance of a processing unit.

Methods and apparatus for varying a supply voltage or reference voltage using independent control of diode voltage in asymmetrical double-gate devices

A test structure for characterizing a production static random access memory (SRAM) array. The test structure includes a characterization circuit having multiple memory cell columns connected in series to form a ring configuration. The characterization circuit is fabricated on a wafer substrate in common with and proximate to a production SRAM array. The characterization circuit preferably includes SRAM cells having a circuit topology substantially identical to the circuit topology of memory cells within the production SRAM array. In one embodiment, the test structure is utilized for characterizing a multi-port memory array and includes multiple memory cell columns connected in series to form a ring oscillator characterization circuit. Each cell column in the characterization circuit includes multiple SRAM cells each having a latching node and multiple data path access nodes. Selection control circuitry selectively enables the multiple data path access nodes for the SRAM cells within the characterization circuit.

Test structure for characterizing multi-port static random access memory and register file arrays

A system and method for implementing arithmetic logic unit (ALU) support for value-based control dependence sequences. According to a first embodiment of the present invention, an ALU generates a carry-out signal designating one of a first and second value as a larger value. In response to the carry-out signal, the ALU updates a storage location with a third value, which is the larger value. According to a second embodiment of the present invention, an ALU generates a carry-out signal designating one of a first and second value as a larger value. In response to the carry-out signal, the ALU updates a storage location with a third value. The third value is a fourth value, if the carry-out signal designates the first value as the larger value or the third value is a fifth value, if the carry-out signal designates the second value as the larger value.

System and method for implementing simplified arithmetic logic unit processing of value-based control dependence sequences

A digital transmission circuit and interface provide selectable power consumption via multiple weighted driver slices, improving the flexibility of an interface while reducing transmitter power consumption, area and complexity when possible. A cascaded series of driver stages is provided by a set of parallel slices and a control logic that activates one or more of the slices, which combine to produce a cascaded active driver circuit. The power consumption/drive level selectability of the slice combination provides a driver that can be fine-tuned to particular applications to provide the required performance at a minimum power consumption level.

Digital transmission circuit and interface providing selectable power consumption via multiple weighted driver slices

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.

Static pulsed bus circuit and method having dynamic power supply rail selection

A dynamic logic gate has a device for charging a dynamic node during a pre-charge phase of a clock. A logic tree evaluates the dynamic node with a device during an evaluate phase of the clock. The dynamic node has a keeper circuit comprising an inverter with its input coupled to the dynamic node and its output coupled to the back gate of a dual gate PFET device. The source of the dual gate PFET is coupled to the power supply and its drain is coupled to the dynamic node forming a half latch. The front gate of the dual gate PFET is coupled to a logic circuit with a mode input and a logic input coupled back to a node sensing the state of the dynamic node. The mode input may be a slow mode to preserve dynamic node state or the clock delayed that turns ON the strong keeper after evaluation.

Dual gate transistor keeper dynamic logic

A delay circuit has a fixed delay path at a lower voltage level, a level converter, and an adjustable delay path at a higher voltage level. The fixed delay path includes an inverter chain, and the adjustable delay path includes serially-connected delay elements selectively connected to the circuit output. In an application for a local clock buffer of a static, random-access memory (SRAM), the lower voltage level is that of the local clock buffer, and the higher voltage level is that of the SRAM. These voltages may vary in response to dynamic voltage scaling, requiring re-calibration of the adjustable delay path. The adjustable delay path may be calibrated by progressively increasing the read access time of the SRAM array until a contemporaneous read operation returns the correct output, or by using a replica SRAM path to simulate variations in delay with changes in voltage supply.

Optimizing SRAM performance over extended voltage or process range using self-timed calibration of local clock generator

A wordline-to-bitline timing ring oscillator circuit for evaluating storage cell access time provides data on internal bitline access timing, and in particular the total wordline select-to-bitline read output timing. Columns of a storage array are connected in a ring, forming a ring oscillator. The bitline read circuit output of each column is connected to a wordline select input of a next column, with a net inversion around the ring, so that a ring oscillator is formed. The period of oscillation of the ring oscillator is determined by the total wordline select-to-bitline read circuit output timing for a first phase and the pre-charge interval time for the other phase, with the bitline read timing dominating. The circuit may be applied both to small-signal storage arrays, with the sense amplifier timing included within the ring oscillator period, or to large-signal storage arrays, with the read evaluate circuit timing included.

Wordline-to-bitline output timing ring oscillator circuit for evaluating storage array performance

A storage array including a local clock buffer with programmable timing provides a mechanism for evaluating circuit timing internal to the storage array. The local clock buffer can independently adjust the pulse width of a local clock that controls the wordline and local bitline precharge pulses and the pulse width of a delayed clock that controls the global bitline precharge, evaluate and read data latching. The delay between the local clock and the delayed clock can also be adjusted. By varying the pulse widths of the local and delayed clock signal, along with the inter-clock delay, the timing margins of each cell in the array can be evaluated by reading and writing the cell with varying pulse width and clock delay. The resulting evaluation can be used to evaluate timing margin variation within a die, as well variation from die-to-die and under varying environments, e.g., voltage and temperature variation.

Storage array including a local clock buffer with programmable timing

A digital transmission circuit and method providing selectable power consumption via multiple weighted driver slices improves the flexibility of an interface while reducing power consumption when possible. A cascaded series of driver stages is provided by a set of parallel slices and a control logic that activates one or more of the slices, which combine to produce a cascaded active driver circuit. The power consumption/drive level selectability of the slice combination provides a driver that can be fine-tuned to particular applications to provide the required performance at a minimum power consumption level.

Digital transmission circuit and method providing selectable power consumption via multiple weighted driver slices

A pulsed ring oscillator circuit for storage cell read timing evaluation provides read strength information. A pulse generator is coupled to a bitline to which the storage cell to be measured is connected. The storage cell thereby forms part of the ring oscillator and the read strength of the storage cell is reflected in the frequency of oscillation. A pulse regeneration circuit is included in the ring so that the storage cell read loading does not cause the oscillation to decay. Alternatively, a counter may be used to count the number of oscillations until the oscillations decay, which also yields a measure of the read strength of the storage cell. The pulse generator may have variable output current, and the current varied to determine a change in current with the storage cell enabled and disabled that produces the same oscillation frequency. The read current is the difference between currents.

Pulsed ring oscillator circuit for storage cell read timing evaluation

A digital circuit with dynamic power and performance control via per-block selectable operating voltage level permits dynamic tailoring of operating power to processing demand and/or compensation for process variation. A set of processing blocks having a power supply selectable from two different power supply voltage levels is provided. The power level of the overall circuit is set by selecting the power supply voltage for each block to yield a combination of blocks that meets operating requirements. Alternatively, one circuit per pair from a set of pairs of redundant logic blocks supplied by the different power supply voltage levels can be selected to meet the operating requirements. The unselected blocks can be disabled by disabling foot devices or disabling transitions at the inputs to the unselected blocks. Performance measurement and feedback circuits can be included to tune the power consumption and performance level of the circuit to meet an expected level.

Digital circuit with dynamic power and performance control via per-block selectable operating voltage

A method for evaluating memory cell performance provides for circuit delay and performance measurements in an actual memory circuit environment. A row in a memory array is enabled along with a set of drive devices that couple each bitline pair to the next in complement fashion to form a cascade of memory cells. The drive devices can be inverters and the inverters can be sized to simulate the bitline read pre-charge device and the write state-forcing device so that the cascade operates under the same loading/drive conditions as the operational with memory cell read/write circuits. The last and first bitline in the row can be cascaded, providing a ring oscillator or the delay of the cascade can be measured in response to a transition introduced at the head of the cascade. Weak read and/or weak write conditions can be measured by selective loading.

Method for evaluating memory cell performance

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Georgetown, TX, United States of America

Kevin John Nowka