A 28 mW 16-bit Digital Signal Processor for the PDC Half-Rate CODEC

Taketora SHIRAISI  Koji KAWAMOTO  Kazuyuki ISHIKAWA  Eiichi TERAOKA  Hidehiro TAKATA  Takeshi TOKUDA  Kouichi NISHIDA  

IEICE TRANSACTIONS on Electronics   Vol.E79-C   No.12   pp.1679-1685
Publication Date: 1996/12/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Low-Power LSI Technologies)
digital signal processor,  CODEC,  low power consumption,  

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A low power consumption 16-bit fixed point Digital Signal Processor (DSP) has been developed to realize a half-rate CODEC for the Personal Digital Cellular (PDC) system. Dual datapath architecture has been employed to execute multiply-accumulate (MAC) operations with a high degree of efficiency. With this architecture. 86.3% of total MAC operations in the Pitch Synchronous Innovation Code Excited Linear Prediction (PSI-CELP) program are executed in parallel, so that total instruction cycles are reduced by 23.1%. The area overhead for the dual datapath architecture is only 3.0% of the total area. Furthermore, in order to reduce power consumption, circuit design techniques are also extensively applied to RAMs. ROMs, and clock circuits, which consume the great majority of power. By reducing the number of precharging bit lines, a power reduction of 49.8% is achieved in RAMs, and above 40% in ROMs. By applying gated clock to clock lines, a power reduction of 5.0% is achieved in the DSP that performs the PSI-CELP algorithm. The DSP is fabricated in 0.5 µm single-poly, double-metal CMOS technology. The PSI-CELP algorithm for the PDC half-rate CODEC can operate at 22.5 MHz instruction frequency and 1.6 V supply voltage. resulting in a low-power consumption of 28 mW.