Energy efficient stochastic computing with Sobol sequences

Energy efficiency presents a significant challenge for stochastic computing (SC) due to the long random binary bit streams required for accurate computation. In this paper, a type of low discrepancy (LD) sequences, the Sobol sequence, is considered for energy-efficient implementations of SC circuits. The use of Sobol sequences improves the output accuracy of a stochastic circuit with a reduced sequence length compared to the use of another type of LD sequences, the Halton sequence, and conventional linear feedback shift register (LFSR)-generated pseudorandom sequence. The use of Sobol sequences leads to a similar or higher accuracy than using Halton sequences for basic arithmetic operations. Sobol sequence generators cost less energy than the Halton counterparts when multiple random sequences are required in a circuit, thus the use of Sobol sequences can lead to a higher energy efficiency in an SC circuit than using Halton sequences.