A low-power matrix transposer using MSB-controlled inversion coding

This paper proposes a low-overhead MSB-controlled inversion coding technique to reduce the transition activity in a matrix transposer a commonly used component in 2-dimensional discrete cosine transform (DCT) and inverse DCT (IDCT) applications. A family of designs is identified in which this technique is applied to different bit slices of the matrix data and the optimal design within the family is determined using transition activity analysis driven by real image sequences. Our results suggest that the optimal design using MSB-controlled inversion coding yields power savings of 33% for DCT data and 46% for IDCT data. These results are remarkable since existing bus-invert coding techniques have high overheads and are only effective for system-level high-capacitive buses.