The network processor contains 16 VLIW CPUs arranged in an 8x2 matrix. It is an evolution of an existing processor architecture [1,2], with additional on-chip memory, increased IO frequency, increased core frequency, and variable core-to-RAM clock multipliers. The I/O improvements increase the packet data bandwidth from 26Gb/s to 40Gb/s, and the memory lookup bandwidth from 64Gb/s to 80Gb/s. The chip, as shown in Fig. 14.6.1, has 97 million transistors on a 19.14mm x 18.23mm die in IBM's 0.18 8SE process technology. Flip-chip assembly is used to connect 964 signal and 1734 power bumps. Seven layers of metal are used along with local interconnect. An in-house designed standard cell library and custom RAMs are developed. The RAMs contain 780kB of on-chip memory. Full scan DFT, functional RAM tests, and IOWrap [3] comprise the test strategy. The core power supply is 1.5V, with 2.5V and 1.5V IO. Core clock multipliers of 2x through 6x in 1/2x increments, and also 1x are supported. The frequency is centered at 580MHz, with fast process parts yielding above 600MHz. A shmoo plot is shown in Fig. 14.6.2. The clock frequency is greater than 2.5x the previous ASIC in another 0.18µm process. Chip power is 20W at 500MHz under typical load.The cell library uses 18-track full height cells and 9-track half height cells. The cells are optimized for speed and for routing in data-path blocks. Typical cells have 8-10 power levels and have decoupling caps built into the higher power level cells to ensure proper performance. The library consists of 343 static, 66 state, 3 dynamic, and 40 block-specific cells.
The architectures of programmable digital signal processors have design constraints with di erent w eights from general purpose microprocessors. These di erences have led to specializations of general purpose microprocessor architectural techniques.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.