Quantification - 2.5 English

Semi-Ternary CAM Search v2.5 LogiCORE IP Product Guide (PG319)

Document ID
PG319
Release Date
2023-05-16
Version
2.5 English

The total width of an entry is calculated as:

Entry Width = KEY_WIDTH + RESPONSE_WIDTH + PRIORITY_WIDTH + 1
The valid bit adds one extra bit to the entry width. In order to access the whole entry in parallel a number of block RAMs or URAMs are used. Block RAMs are allocated in data width increments of 64 bits. URAMs are allocated in data width increments of 128 bits (except for entry widths of 64 bits and less). To avoid quantification losses it is beneficial if the entry size is close below or on a data width boundary. For example, if the total block RAM entry size is 308 bits, the quantification loss is only 12 bits per entry: 5*64 - 308 = 12.

The maximum supported entry widths are listed in the following table.

Table 1. Maximum Supported Entry Widths
DEPTH MEMORY_PRIMITIVE ENTRY_WIDTH
512 BLOCK 1536
1024 BLOCK 768 1
2048 BLOCK 384 1
2048 ULTRA 2048
4096 ULTRA 1024
8192 ULTRA 512
16384 ULTRA 256 1
  1. Not available for RAM_FREQ over 400 MHz.