Improved bus-shift coding for low-power I/O

Abstract

In low-power VLSI design good amount of power can be saved by using coding scheme such as Bus-Invert (BI). Such a coding scheme looks at successive words on a data bus and applies transformation to minimize the number of transitions. In this paper we propose Bus-Shift (BS) coding scheme that circularly shifts the data to minimize transitions. Power saving of BI is poor on average cases, and even that deteriorates with wider bus width. In comparison the proposed BS scheme performs better in both maximum and average cases. For wide bus the savings from BS gets slightly worse, but still performs better than BI. Simulation results show a saving margin of 14% in average cases for a 32 bit bus. Comparison is also made with Shift-Invert (SINV), another reported coding scheme. An implementation of BS in Cadence is presented.

Analysis of Pointing Loss Effects in Deep Space Optical Links

“…In this section we report the comparison of bus encoding schemes, using the average Hamming distance of two consecutive bus usages D(k, b), as given by ( 6), ( 8), ( 24), ( 25), (29), and (30). Note that the only approximation that needs to be checked with simulation is (30), while for the other schemes we have the exact theoretical analysis.…”

“…In this section we show an easy-to-implement scheme similar to the random scheme, but where the (20), instead of being obtained by EXOR with randomly generated sequences, are obtained by the circular shift of i positions of u j . A similar solution has been proposed in [24] and extended in [29] without bus inversion. We here combine the circular shift with bus inversion.…”

“…In the context of bus encoding, and assuming the energy consumption is mainly related to status line changes, several techniques have been proposed to reduce the number of transitions between successive uses of the bus, starting from the seminal works in [5]- [7], [24], [25]. Some of these works assume a memoryless source, emitting random binary tuples to be transported over the bus [5]- [8], [24], [26]- [29], others focus on sources with memory [25], [30]- [36]. The performance of these schemes has been obtained by simulations for some specific parameters choice.…”

Energy-Efficient Time-Based Adaptive Encoding for Off-Chip Communication

“…The effectiveness of this technique is restricted to highly correlated data streams such as image files. Bus Shifting (BS) rotates the word to be transmitted by a number of bits to minimise transitions and uses spatial redundancy to send this number to the decoder [20]. However, the calculation of Hamming distance for all possible rotations of each data word increases significantly the hardware complexity.…”

Performance of rc low encoding techniques for reducing coupling transitions

“…Capacitance ratio is defined as coupling capacitance to load capacitance = C C / C L The Total Power in the Bus Model is Given By P= C.V 2 DD .f In the above power can be minimized by using capacitance in which The Rate of low of data and charging, discharing can be make to control the power by using encoding techniques 3.count the change of bits from t to t-1 that is coupling count count. 4.compare the coupling count count value with half of width of bus and quarter width of bus.…”