CEVA introduces DSP core for 4G handset basebands

EDN Europe, 11 Feb 2009

CEVA, designer of silicon intellectual property (IP), focuses on DSP cores, especially those used in the baseband of cellular and other digital communications systems. Its CEVA-X architecture is widely used in 2, 2.5 and 3G (second/third-generation) cellular handsets. Now, it has introduced the CEVA-XC core for use in 3.5 and 4G radio designs. XC is a fully-programmable core that will enable a software solution for LTE Class 5 or WiMax II, which equates to a downlink data rate of 300 Mbits/sec with 4x4 MIMO. Terminal designers can handle the full transceiver path in software; CEVA says that the core will deliver up to 200 billion operations per second (Bops); 4G ands software-defined-radio systems need 20-times the processing power of 3.5G. The core provides very high DSP efficiency, CEVA says, at up to 64 multiply-accumulate operations per cycle, working on vector data. The company supplies an optimised C compiler and says that you can achieve peak processing efficiency with a pure-C design with no special extensions. The architecture includes a power scaling unit that adjusts both voltages and clock rate depending on mode, and also turns off blocks when not required.

Simulation results for power show 10 mW to process a 50 Mbps LTE downlink, for a core implemented in 65-nm silicon – actual 4G chipsets will be in 40 nm or even smaller geometries and CEVA expects power to be correspondingly less. The design is scalable, with up to four “vector communications units” that carry our much of the intensive DSP processing on 256-bit data. Each vector unit consists of a 256-bit SIMD engine using 3-way VLIW and a large array of 16 MAC, arithmetic, logic and shift units. An optimised instruction set handles the requirements of wireless modems, including matrix processing, MIMO detectors, filtering, complex data permutations and bit stream processing. There is also a general computation unit for control and other DSP functions. All of the special functions required in 4G designs have specific support, including DSP library functions.