Variable length code decoder using a content addressable memory with match inhibiting gate

Number of patents in Portfolio can not be more than 2000

United States of America Patent

PATENT NO 5642114
SERIAL NO

08351253

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ATTORNEY / AGENT: (SPONSORED)

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Abstract

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The present invention relates to a variable-length code decoding circuit for decoding an input variable-length code string and a variable-length code decoding system using the same. A typical variable-length code decoding circuit of the present invention includes a CAM cell 10 for storing a variable-length code bit and a RAM cell 20 which is paired with the CAM cell 10 for storing a mask bit so as to perform a masking operation. The variable-length code decoding circuit further includes an NMOS transistor 30 which is coupled between the CAM cell 10 and a match line ML for selectively disconnecting the CAM cell 10 from the match line ML in response to an output of the RAM cell 20. The CAM cell 10 collates a bit of the input variables-length code string with the stored code bit. When the input bit matches the stored code bit, the CAM cell 10 outputs an H level matching to the match line ML and otherwise it outputs an L level unmatching to the match line ML. If the CAM cell 10 does not relate to the collating operation that is, if it does not matter whether there is a match, the RAM cell 20 corresponding to the CAM cell 10 outputs an L level signal to turn off the NMOS transistor 30. When the NMOS 30 is turned off, the output of the CAM cell 10 is not transmitted to the match line ML.

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Patent Owner(s)

Patent OwnerAddressTotal Patents
LAPIS SEMICONDUCTOR CO., LTD.HACHIOJI-SHI TOKYO1622

International Classification(s)

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Inventor(s)

Inventor Name Address # of filed Patents Total Citations
Komoto, Eiji Tokyo, JP 10 101
Nakamura, Takao Tokyo, JP 195 1987

Cited Art Landscape

Patent Info (Count) # Cites Year
 
TTI INVENTIONS A LLC (1)
* 5173695 High-speed flexible variable-length-code decoder 120 1990
 
TELCORDIA TECHNOLOGIES, INC. (1)
* 5245338 High-speed variable-length decoder 39 1992
 
MAGNACHIP SEMICONDUCTOR, LTD. (1)
* 5475389 Adaptive variable-length coding apparatus 5 1994
 
TEKTRONIX, INC. (1)
* 4670858 High storage capacity associative memory 97 1983
* Cited By Examiner

Patent Citation Ranking

Forward Cite Landscape

Patent Info (Count) # Cites Year
 
GLOBALFOUNDRIES INC. (1)
6452822 Segmented match line arrangement for content addressable memory 20 2001
 
ALTERA CORPORATION (3)
* 5940852 Memory cells configurable as CAM or RAM in programmable logic devices 39 1997
* 6058452 Memory cells configurable as CAM or RAM in programmable logic devices 56 1999
* 6263400 Memory cells configurable as CAM or RAM in programmable logic devices 10 2000
 
SUN MICROSYSTEMS, INC. (1)
* 6078987 Translation look aside buffer having separate RAM arrays which are accessable with separate enable signals 22 1997
 
ORACLE AMERICA, INC. (1)
* 5936873 Single ended match sense amplifier 33 1997
 
ESILICON CORPORATION (1)
* 6134135 Mask arrangement for scalable CAM/RAM structures 40 2000
 
NEC CORPORATION (1)
* 5787458 Content addressable memory of a simple construction capable of retrieving a variable word length data 40 1996
 
MITSUBISHI ELECTRIC CORPORATION (2)
8291150 Table device, variable length coding apparatus, variable length decoding apparatus, and variable length coding and decoding apparatus 0 2007
* 2010/0057,810 TABLE DEVICE, VARIABLE LENGTH CODING APPARATUS, VARIABLE LENGTH DECODING APPARATUS, AND VARIABLE LENGTH CODING AND DECODING APPARATUS 4 2007
 
KAWASAKI MICROELECTRONICS, INC. (1)
* 6646900 Ternary content addressable memory with data and mask data settable therewithin by one write cycle 19 2002
 
SANDISK CORPORATION (3)
6317349 Non-volatile content addressable memory 56 1999
* 6166938 Data encoding for content addressable memories 58 1999
* 6157558 Content addressable memory cell and array architectures having low transistor counts 54 1999
 
STMICROELECTRONICS S.A. (1)
6995997 Cache cell with masking 0 2004
 
GOOGLE INC. (1)
* 6615310 Lossless data compressor with all CAM words available 2 2000
 
AVAGO TECHNOLOGIES GENERAL IP (SINGAPORE) PTE. LTD. (15)
6418042 Ternary content addressable memory with compare operand selected according to mask value 40 1998
* 6137707 Method and apparatus for simultaneously performing a plurality of compare operations in content addressable memory device 110 1999
6460112 Method and apparatus for determining a longest prefix match in a content addressable memory device 47 1999
7143231 Method and apparatus for performing packet classification for policy-based packet routing 10 1999
6539455 Method and apparatus for determining an exact match in a ternary content addressable memory device 37 1999
6499081 Method and apparatus for determining a longest prefix match in a segmented content addressable memory device 55 1999
* 6154384 Ternary content addressable memory cell 122 1999
6944709 Content addressable memory with block-programmable mask write mode, word width and priority 38 2001
6934795 Content addressable memory with programmable word width and programmable priority 45 2001
6892272 Method and apparatus for determining a longest prefix match in a content addressable memory device 9 2002
6574702 Method and apparatus for determining an exact match in a content addressable memory device 29 2002
* 6809945 Content addressable memory match line sensing techniques 0 2003
7272027 Priority circuit for content addressable memory 3 2004
* 2004/0193,741 Priority circuit for content addressable memory 10 2004
7246198 Content addressable memory with programmable word width and programmable priority 12 2005
 
NEC ELECTRONICS CORPORATION (1)
* 6404359 Variable length decoding system having a mask circuit for improved cache hit accuracy 2 2000
 
PHILIPS ELECTRONICS NORTH AMERICA CORPORATION (1)
* 5835035 High performance variable length decoder with two-word bit stream segmentation and related method 9 1997
* Cited By Examiner