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CADRE: A Low-Power, Low-EMI DSP Architecture for Digital Mobile Phones
M. Lewis, L.E.M. Brackenbury
Current mobile phone applications demand high performance from the DSP, and future generations are likely to require even greater throughput. However, it is important to balance these processing demands against the requirement of low power consumption for extended battery lifetime. A novel low-power digital signal processor (DSP) architecture CADRE (Configurable Asynchronous DSP for Reduced Energy) addresses these requirements through a multi-level power reduction strategy. A parallel architecture and configurable compressed instruction set meets the throughput requirements without excessive program memory bandwidth, while a large register file reduces the cost of data accesses. Sign-magnitude representation is used for data, to reduce switching activity within the datapath. Asynchronous design gives fine-grained activity control without the complexities of clock gating, and gives low electromagnetic interference. Finally, the operational model of the target application allows for a reduced interrupt structure, simplifying processor design by avoiding the need for exact exceptions.