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Circuit and method for subdividing a CAMRAM bank by controlling a virtual ground

A virtual ground and circuit technology, applied in the field of digital electronics, can solve the problem of wasting silicon area

Inactive Publication Date: 2009-01-14
QUALCOMM INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this requires a larger number of CAM banks 122, duplicating CAM driver circuits 126, which wastes silicon area

Method used

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  • Circuit and method for subdividing a CAMRAM bank by controlling a virtual ground
  • Circuit and method for subdividing a CAMRAM bank by controlling a virtual ground
  • Circuit and method for subdividing a CAMRAM bank by controlling a virtual ground

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Embodiment Construction

[0021] According to one or more embodiments, the CAM bank 122 is subdivided into two or more sub-banks that share the CAM driver circuitry 126 . All discharge circuits 105 in CAM bank 122 are deactivated by raising the ground voltage level to which circuits 105 discharge from circuit ground to a voltage level above ground sufficient to prevent discharge of match line 102 . This elevated voltage level is referred to herein as virtual ground. The selected plurality of CAM entries 100 in the CAM bank 122 may then be enabled by pulling the virtual ground of the discharge circuit 105 in the selected CAM entry 100 to circuit ground. The entry operation is then selected and an active sub-library of CAM entries 100 is formed. In this manner, CAM block 122 may be subdivided without duplication of CAM driver circuit 126 .

[0022] image 3A representative discharge circuit 105 is schematically depicted in , which generally corresponds to the dashed line discharge circuit 105 of FIG. ...

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Abstract

A CAM bank is functionally divided into two or more sub-banks, without replicating CAM driver circuits, by disabling all match line discharge circuits in the bank, and selectively enabling the discharge circuits in entries comprising sub-banks. At least one selectively actuated switching circuit is interposed between the virtual ground node of each discharging comparator in the discharge circuit of a sub-bank and circuit ground. When the switching circuit is in a non-conductive state, the virtual ground node is maintained at a voltage level sufficiently above circuit ground to preclude discharging a connected match line within the CAM access time. When the switching circuit is placed in a conductive state, the virtual ground node is pulled to circuit ground and the connected match line may be discharged by a miscompare. Control signals, which may be decoded from address bits, are distributed to the switching circuits to define the CAM sub-banks.

Description

technical field [0001] The present invention relates generally to the field of digital electronics, and in particular to a circuit and method for subdividing a CAMRAM (Content Addressable Memory Random Access Memory) bank via a virtual ground. Background technique [0002] Microprocessors perform computing tasks in a variety of applications including embedded applications such as portable electronic devices. The ever-growing feature sets and increased functionality of such devices require more computationally powerful processors to provide additional functionality via software. Another trend in portable electronic devices is ever-shrinking form factors. A major impact of this trend is the reduced size of the batteries used to power the processor and other electronics in the device, making power efficiency an increasingly important design consideration. Accordingly, there is a need for processor improvements that increase execution speed and reduce power consumption, for ce...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G11C15/04
CPCG11C15/04G11C8/12G11C15/00
Inventor 迈克尔·泰坦·潘蔡贾名杰弗里·托德·布里奇斯杰弗里·赫伯特·费希尔
Owner QUALCOMM INC