A reconfigurable linear feedback shift register (LFSR) for the Bluetooth system

Abstract

The Bluetooth Encryption/Decryption algorithm demands Linear Feedback Shift Registers (LFSRs) in order to reduce the length of the encryption key. A typical implementation needs sixteen different LFSRs. In this paper a low power 128-bit LFSR for efficient use in portable Bluetooth telecommunication systems is proposed. The new LFSR design techniques can be also useful in any reconfigurable LFSR. Two methods to reduce the conventional LFSR switching activity are introduced. Up to 110% LFSR power consumption reduction was achieved by using the clock-gating technique and the Gray code representation. The whole LFSR design was captured by using VHDL language and for synthesis a 0.7 /spl mu/m CMOS standard cell library was used.