International Business Machines Corporation

Michael Ju Hyeok Lee

Jose Angel Paredes

Peter Juergen Klim

Sam Gat-Shang Chu

Yuen H Chan

Philip George Shephard, Iii

Ed Seewann

Masood Ahmed Khan

Edelmar Seewann

Vikas Agarwal

Bao G Truong

Eric Jason Fluhr

Andrew James Bianchi

William Vincent Huott

Juergen Pille

Sheldon Bernard Levenstein

Rolf Sautter

Jason Frederick Cantin

Joaquin Hinojosa

Elspeth Anne Huston

Philip George Iii Shephard

A memory includes an array of memory cells that form rows and columns. The rows of the array include memory cell pairs. The memory cells may include two cross-coupled inverters and two pass-devices that couple to alternate sides of the cross-coupled inverters. The two memory cells of a memory cell pair share a common intra-pair bitline. Adjacent memory cell pairs share a common inter-pair bitline. To perform a data read operation on a particular memory cell in a memory cell pair in the rows and columns of the array, wordline drive circuitry transmits wordline activate signals to select both the row for the data read operation and a particular one of the pair of memory cells for the data read operation.

Volatile memory access via shared bitlines

A programmable clock control circuit includes a base block, a chop block, and a pulse width variation block coupled between the chop block and the base block that receives the chop block output and provides a pulse width variation output to the base block. The pulse width variation block is programmable to vary the chop block output to provide at least three different output pulse widths. The circuit also includes a clock delay block coupled an output of the base block to delay the output pulse and having a clock signal output.

Progamable control clock circuit for arrays

A data input latch and clocking method and apparatus for high performance SRAM in which an L1 data input latch is controlled by a logical combination of the normal local clock buffer clock signal and the local array clock buffer clock signal. This logical combination of clock signals minimizes the hold time of the L1 latch provides a fast cycle time in which the SRAM macro can process successive write instructions while avoiding early mode issues.

Array data input latch and data clocking scheme

An information handling system (IHS) includes a processor with on-chip or off-chip SRAM array. After a read operation, a control circuit may instruct the SRAM array to conduct a precharge operation, or alternatively, instruct the SRAM array to conduct an equalize bitline voltage operation. A read operation may follow the precharge operation or the equalize bitline voltage operation. The control circuit may instruct the SRAM array to conduct an equalize bitline voltage operation if an equalized voltage of a bitline pair exhibits more that a predetermined amount of voltage. Otherwise, the control circuit instructs the SRAM array to conduct a precharge operation before the next read operation.

Information handling system with SRAM precharge power conservation

A system and computer program for verifying performance of an array by simulating operation of edge cells in a full array model reduces the computation time required for complete design verification. The edge cells of the array (or each subarray if the array is partitioned) are subjected to a timing simulation while the center cells of the array are logically disabled, but remain in the circuit model, providing proper loading. Additional cells are specified for simulation if calculations indicate a worst-case condition due to a non-edge cell. Wordline arrivals are observed to determine worst-case rows for selection. For write operations, the difference between the wordline edges and the data edges is used to locate any non-edge 'outlier' cells. For read operations, the wordline delays are summed with the bitline delays determined from edge column data to locate any outliers.

System and computer program for verifying performance of an array by simulating operation of edge cells in a full array model

A method, system and apparatus for detecting soft errors in non-dataflow circuits. In a preferred embodiment, input is received at a latch system. The latch system consists of two pairs of latches. The second pair of latches is parallel to the first pair of latches. Both pairs of latches capture the input. However, the second pair of latches captures the input later in time relative to the first pair of latches latch. The captured input is then transferred from the first latch in each pair of latches to the second latch in each pair of latches. A comparison is made of the input in the two second latches. If the input captured in the two second latches is not the same, then a message is sent to a recovery unit.

Transient noise detection scheme and apparatus

A method and apparatus for using a 2:1 MUX to control read access, data bypass, and page size bypass in a memory array. The mechanism of the present invention reduces the 3:1 MUX normally required to manage these three functions to a 2:1 MUX.

Efficient muxing scheme to allow for bypass and array access

A method for verifying performance of an array by simulating operation of edge cells in a full array model reduces the computation time required for complete design verification. The edge cells of the array (or each subarray if the array is partitioned) are subjected to a timing simulation while the center cells of the array are logically disabled, but remain in the circuit model, providing proper loading. Additional cells are specified for simulation if calculations indicate a worst-case condition due to a non-edge cell. Wordline arrivals are observed to determine worst-case rows for selection. For write operations, the difference between the wordline edges and the data edges is used to locate any non-edge 'outlier' cells. For read operations, the wordline delays are summed with the bitline delays determined from edge column data to locate any outliers.

Method for verifying performance of an array by simulating operation of edge cells in a full array model

A content addressable memory (CAM) system is disclosed including a dual mode cycle boundary latch (CBL). The CBL includes a master latch coupled to a slave latch. The CBL operates in a high speed functional mode and a lower speed test mode. In the high speed functional mode, input data bypasses the master latch and transports directly to the CBL output via the slave latch. The CBL effectively removes the master latch from the circuit in the high speed functional mode. However, in the lower speed test mode, input test data travels via both the master and slave latches to the CBL output.

Content addressable memory including a dual mode cycle boundary latch

A method and apparatus for ensuring proper operation of a dynamic circuit is provided. A dynamic circuit instance has a plurality of outputs connected to a respective one of a plurality of leakage detector circuits. An output of each leakage detector circuit is connected with a respective one of a plurality of keeper circuits that reside at the dynamic circuit. Each of the plurality of keeper circuits has a unique size ratio with respect to a logic element size of the dynamic circuit.

Leakage sensing and keeper circuit for proper operation of a dynamic circuit

A CAM system is disclosed in which compare data, for example an address translation request, is provided as input search data to a search line generator. The search line generator presents search line input data, through a buffer, to CAM and RAM array systems that include dynamically precharged and evaluated memory cells. Timing sequences in the CAM system are controlled by a series of individually triggered one shot pulse generators. The one shot pulse generators control the timing of CAM system activities, for example the precharge of CAM subsystems, so that these activities are staggered in time. This timing approach improves power consumption and evaluation time within the CAM system. By distributing precharging activities in time throughout the CAM cycle, current peaking during the CAM cycle is reduced. The CAM system latches results in an output latch that is controlled by a one shot pulse generator.

Method and apparatus for controlling the timing of precharge in a content addressable memory system

A register file method incorporating read-after-write blocking using detection cells provides improved read access times in high performance register files. One or more detection cells identical to the register file cells and located in the register file array are used to control the read operation in the register file by configuring the detection cells to either alternate value at each write or change to a particular value after a write and then detecting when the write has completed by detecting the state change of an active detection cell. The state change detection can be used to delay the leading edge of a read strobe or may be used in the access control logic to delay generation of a next read strobe. The register file thus provides a scalable design that does not have to be tuned for each application and that tracks over voltage and clock skew variation.

Register file method incorporating read-after-write blocking using detection cells

A CAM system is disclosed in which requests for address translation are provided as input search data to a dynamic compare bitline generator. The dynamic compare bitline generator also receives a compare mask and applies the compare mask to associated input search data bits on a per bit basis. The mask contains information that specifies a selected page size and a selected logic mode that can be applied to a compare array in which the specified search is conducted. The compare array is coupled to a data array to which the compare array indicates a result of the search.

Method and apparatus for selecting operating characteristics of a content addressable memory by using a compare mask

An apparatus and method is provided that combines both self test and functional features in a single latch circuit, which may be used with an SRAM array and is usefully embodied as an L1-L2 latch. During partial writes from an SRAM array, data bits of unknown state are inhibited from entering the latch circuit, while data for testing is allowed to enter. In one useful embodiment of the invention the latch circuit is used with a mode control that provides mode select signals to operate the latch circuit in one of a plurality of modes, including at least full write and partial write modes. The latch circuit further includes a data hold circuit for selectively receiving and storing data coupled to the latch circuit. A first enabling circuit responsive to the mode select signals enables the hold circuit to receive all the data contained in the array during a full write mode, and further enables the hold circuit to receive only some of the data bits contained in the array during a partial write mode.

Multifunctional latch circuit for use with both SRAM array and self test device

An apparatus and method are disclosed for detecting multiple hits in CAM arrays. A binary address value is stored for each entry of the CAM array and is output to identify the matching entry for a single hit. However, to facilitate multiple hit detection, both the true and complement components of this address are stored and output to determine whether or not a multiple hit occurred. If a multiple hit occurs (e.g., more than one address location has been matched), all the bits that make up the binary address and the complement will not be complements of each other and a multiple hit condition can be detected by XORing each bit of an address location value with the complement of that address location value. If the XORed bits are equal to '1', then a single hit has occurred. Otherwise, a multiple hit has occurred.

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Austin, TX, United States of America

Michael Ju Hyeok Lee