| Summary: | 碩士 === 國立清華大學 === 電機工程學系 === 103 === The development of embedded systems and wireless technology has led to a wide range of applications; however, the storage of data associated with these applications presents serious difficulties, particularly when dealing with long standby time and discontinuous power supply. This has led to the development of cloud servers and databases; however the transmission of invalid data between the cloud and local devices plays a major role in overall power consumption. By implementing a filter capable of identifying the input data, devices can reduce the amount of data that must be sent to the cloud, and further reduce the overall power consumption.
TCAM is meant to address the needs for more speed and large storage. However, for the feature of normally-off, we need the Nonvolatile Memory to reduce large standby power companying with large storage. The implementation of non-volatile memory in TCAM generally involves a 2-macro solution, which includes a SRAM-based TCAM macro with a nonvolatile memory macro, such as flash. In power-off mode, the TCAM macro stores data within a nonvolatile memory macro. In power-on mode, the data is restored from the nonvolatile memory macro. Unfortunately, limited I/O bandwidth can produce large delays and induce large energy consumption associated with the movement of data in power-on and power-off operations.
This study developed a single macro solution, which is capable of reducing area overhead, minimizing store/restore energy, and speeding up store/restore operations. The proposed method does not require the movement of data and enables immediate power-on/off switching, based on the fact that only logic-based peripheral circuits need to be woken up..
This study proposed a bi-directional voltage divider control (BVDC) 3T1R nonvolatile TCAM (nvTCAM) which can reach:
1. 1/5 times smaller than traditional 16T SRAM-based TCAM, and 5 times larger capacity with same area.
2. Fast and low power wake-up and backup operations.
3. 1.33 times smaller NVM device write energy than other 2R-based nvTCAM.
The capacity of implemented macro is 4kbits, and 0.96ns search time is achieved. The measured search speed is the most fast one compared with other published nvTCAM.
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