Cypress Semiconductor Corporation

Netlogic Microsystems, Inc

Ajay Srikrishna

Jeffery Scott Hunt

Satish C Saripella

Sudhaker Reddy Anumula

Srinivasan Venkatachary

Andrew L Hawkins

Muthukumar Nagarajan

George M Ansel

Mark Birman

Jeffrey William Waldrip

Jagadeesan Rajamanickam

Manoj B Roge

Nabil Masri

Hari Om

A content addressable memory device () and method can have CAM blocks (-to-) organized in block sections (-to-). In an overlay mode of operation, an overlay engine () can access an algorithmic search (SPEAR) CAM (-and-) to generate overlay data set search keys (keyFIB&#x3c;&#x3e; and &#x3c;&#x3e;). Multiple data sets (e.g., FIB, FIB, ACL) can be accommodated on the same CAM device by search key multiplexers (-to-) that selectively apply any of a number of data set search keys (keyACL&#x3c;&#x3e;, keyFIB&#x3c;&#x3e; and keyFIB&#x3c;&#x3e;).

Method and apparatus for overlaying flat and/or tree based data sets onto content addressable memory (CAM) device

Method and apparatus for overlaying flat and tree based data sets onto content addressable memory (CAM) device

A search engine method and apparatus can store and update status information for each entry of a content addressable memory (CAM) array, for a learn operation, or the like. A search engine can include a status memory block external to and independent of the CAM array. A status memory block () can include a number of memory sections (-to-) that each includes a number of bit locations for storing a free/not-free status of CAM entries in a hierarchical fashion. Corresponding control sections (-to-) can include priority encoders (-to-) that determine a first free element in a memory section for a next hierarchical level, as well as status aggregation logic (-to-) that can generate an aggregated status that is propagated to a previous hierarchical level.

Method and apparatus for learn and related operations in network search engine

A content addressable memory (CAM) device () can receive a compare data value having a native word size. The compare data value can be split into smaller portions, with one portion can be applied to a first CAM block (-) and another being applied to a second CAM block (-) on a subsequent clock (CAMCLK) cycle. Activation of circuit elements in the second CAM block (-) can be conditioned on first match results (CMATCHAto CMATCHA) generated by first CAM block (-).

Staggered compare architecture for content addressable memory (CAM) device

Architecture, circuitry and method are provided for a ternary content addressable memory (TCAM), and use thereof. Each TCAM cell is relatively small in size. If the TCAM cell is called upon to store voltage values indefinitely, provided power is retained on the cell, the TCAM cell employs no more than 16 transistors. Additional savings in size is achieved by using a single common conductor (or dual common conductors in a differential arrangement) to suffice as both the bit line and compare line. The common bit line and compare line connects to not only the X memory cell, but also the Y memory cell and the compare circuit of the TCAM cell. The compare circuit can either be activated or deactivated. During a compare operation, the compare circuit is selectively activated by placing a ground supply upon a match line enable conductor. The ground supply is imputed upon the match line whenever a mismatch occurs to designate that mismatch. Otherwise, during a normal read or write operation, the match line enable is placed at the same voltage value as the pre-charged match line.

Bit encoded ternary content addressable memory cell

A circuit and method comprising a memory, a first latch, a second latch and a control circuit. The memory may be configured to write information in response to (i) an input data signal and (ii) an address signal. The first latch may be configured to hold the address in response to a control signal. The second latch may be configured to hold the data input signal in response to the control signal. The control circuit may be configured to present the control signal in response to (i) an enable signal and (ii) a detect signal.

Method, architecture and circuit for writing to and reading from a

A reference voltage generator may include an input for receiving a first voltage for input to a sense amp. The reference voltage generator may also include an output for outputting a second voltage for input to the sense amp. The second voltage is influenced by the first voltage. Alternatively, a reference voltage generator may include a first input for receiving a first voltage on a first bitline. The reference voltage generator may also include a first output for outputting a second voltage on a second bitline. The second voltage is influenced by the first voltage. Alternatively, a reference voltage generator may include a first input for receiving a first voltage on a first transmission busline. The voltage generator may also include a first output for outputting a second voltage on a second transmission busline. The second voltage is influenced by the first voltage.

Reference voltage generator for reading a ROM cell in an integrated

A circuit and method comprising a memory, a first latch, a second latch and a control circuit. The memory may be configured to write information in response to (i) an input data signal and (ii) an address signal. The first latch may be configured to hold the address in response to a control signal. The second latch may be configured to hold the data input signal in response to the control signal. The control circuit may be configured to present the control signal in response to (i) a detect signal and (ii) a transition of the address signal.

Method, architecture and circuit for writing to a memory

A circuit comprising a sense amplifier, an evaluation circuit, a control circuit and a register circuit. The sense amplifier circuit may be configured to present a first output and a second output in response to (i) an input signal and (ii) an enable signal. The evaluation circuit may be configured to present an evaluation signal in response to the first and second outputs. The control circuit may be configured to present (i) a first clock signal, a second clock signal and an enable signal in response to (i) the evaluation signal and (ii) a wordline signal. The register circuit may be configured to hold either the first or second output in response to the first and second clock signals. The register circuit may be implemented as a master-slave register that may respond to the first and second clock signals.

Method, architecture and circuit for reducing and/or eliminating small

A method and apparatus for greatly simplifying the circuitry needed to handle the bubbleback situations in FIFO memories includes an additional row of cells added to the memory array. By adding an extra row of memory cells, the read and write pointer are only on the same row when the FIFO is operating near the empty boundary or in fallthrough mode.

Bubbleback for FIFOS

A memory device includes a random access memory (RAM) cell accessible through a RAM wordline and coupled between first and second bitlines; a read only memory (ROM) cell accessible through a ROM wordline and having an output coupled to the first bitline and an input configured to receive a first voltage signal; and a reference voltage generator having a first input coupled to the first bitline, a second input configured to receive the first voltage signal, and an output coupled to the second bitline. The memory device may further include a bitline load having an output coupled to the first bitline. A virtual ground driver configured to produce the first voltage signal may be coupled to the input of the read only memory cell. Further, column select pass gates configured to be under the control of a logic signal and having a first input coupled to the first bitline, a second input coupled to the second bitline, a first output and a second output may be provided. A sense amplifier having a first input coupled to the first output of the column select pass gates and a second input coupled to the second output of the column select pass gates may be included in the memory device. The memory device may be read by modulating a first voltage input to the sense amplifier using a second voltage input to the sense amplifier.

Read only/random access memory architecture and methods for operating

A method and apparatus for writing data onto the read bitline when a FIFO buffer memory is nearly empty that includes circuitry detecting when a memory is nearly empty, when the read pointer and the write pointer are on the same line with the read pointer behind the write pointer. Another circuit writes data onto the read bitline as the data is written into the buffer memory.

Growing community of inventors

Starkville, MS, United States of America

Ajay Srikrishna