A Virtex-5 FPGA CLB resource is made up of two slices.
Each slice is equivalent and contains:
• Four function generators
• Four storage elements
• Arithmetic logic gates
• Large multiplexers
• Fast carry look-ahead chain

The function generators are configurable as 6-input LUTs or dual-output 5-input LUTs. SLICEMs in some CLBs can be
configured to operate as 32-bit shift registers (or 16-bit x 2 shift registers) or as 64-bit distributed RAM. In addition, the
four storage elements can be configured as either edge-triggered D-type flip-flops or level sensitive latches.
Each CLB has internal fast interconnect and connects to a switch matrix to access general routing resources.

• Most advanced, high-performance, optimal-utilization, FPGA fabric
− Real 6-input look-up table (LUT) technology
− Dual 5-LUT option
− Improved reduced-hop routing
− 64-bit distributed RAM option
− SRL32/Dual SRL16 option

• Powerful clock management tile (CMT) clocking
− Digital Clock Manager (DCM) blocks for zero delay buffering, frequency synthesis, and clock phase shifting
− PLL blocks for input jitter filtering, zero delay buffering, frequency synthesis, and phase-matched clock division