CAM cells for high speed and lower power content addressable memory (CAM) and ternary content addressable memory (TCAM)
OwnerXiaohua Huanginventor
Life of this patent
Estimating the term…
Abstract
A few dummy Content-addressable memory (CAM) cells and a few dummy Ternary Content-addressable memory (TCAM) cells which connect to each corresponding row in CAM and TCAM array to enable or disable the comparison in differential match line sensing based on the content stored the Ternary content-addressable memory (TCAM) cells are disclosed for differential match line sensing in low power application. Methods which generate the voltage difference between match line signal and reference line signal, then detect and amplify it to determine match or mismatch are described.
Claims8
A content addressable memory (CAM) cell comprising:
- a memory cell operable to store a bit value;
- and
- a comparison circuit coupled to the memory cell and configured to detect the bit value stored in the memory cell, the comparison circuit including
- the output transistors coupled to a match line and configured to provide a logic comparison between the stored bit and the input bit as well as drive for the match line based on the result of comparison, and
- the dummy transistors coupled to a dummy line, wherein the match line and dummy line are used to detect an output value provided by the CAM cell.
A Ternary content addressable memory (CAM) cell comprising:
- a memory cell operable to store a data bit value;
- a secondary cell operable to store a control bit value;
- and
- a comparison circuit coupled to the memory cell and the secondary cell and configured to detect the data bit value stored in the memory cell and the control bit value stored in the secondary cell, the comparison circuit including
- a few pair of output transistors coupled to a match line and configured to provide a drive for the match line based on the detected data bit value and the detected control bit value, and
- a few pairs of dummy transistors coupled to a dummy line, wherein the match line and dummy line are used to detect an output value provided by the CAM cell.
A dummy content addressable memory (CAM) cell comprising:
- a memory cell operable to store a data bit value;
- a secondary cell operable to store a control bit value;
- and
- a comparison circuit coupled to the memory cell and the secondary cell and configured to detect the data bit value stored in the memory cell and the control bit value stored in the secondary cell, the comparison circuit including
- a pair of output transistors coupled to a match line and configured to provide a drive for the match line based on the detected data bit value and the detected control bit value, and
- a pair of dummy transistors coupled to a dummy line and configured to provide a drive for the dummy line based on an inverted detected data bit value and the detected control bit value.
Dependencies are inferred from the claim text.