Multiplier less high-speed squaring circuit for binary numbers

The squaring operation is important in many applications in signal processing, cryptography etc. In general, squaring circuits reported in the literature use fast multipliers. A novel idea of a squaring circuit without using multipliers is proposed in this paper. Ancient Indian method used for squaring decimal numbers is extended here for binary numbers. The key to our success is that no multiplier is used. Instead, one squaring circuit is used. The hardware architecture of the proposed squaring circuit is presented. The design is coded in VHDL and synthesised and simulated in Xilinx ISE Design Suite 10.1 (Xilinx Inc., San Jose, CA, USA). It is implemented in Xilinx Vertex 4vls15sf363-12 device (Xilinx Inc.). The results in terms of time delay and area is compared with both modified Booth’s algorithm and squaring circuit using Vedic multipliers. Our proposed squaring circuit seems to have better performance in terms of both speed and area.     

Systematic synthesis of approximate adders and multipliers with accurate error calculations

In this study, we perform logic synthesis and area optimization of approximate ripple-carry adders and Wallace-tree multipliers with a given error constraint. We first implement approximate 1-bit adders having different error rates as building blocks of the proposed multi-bit adders and multipliers. In implementations, we exploit offsetting errors in carry and sum outputs of the adders. Also we take into account the probability of occurrence of input assignments. Using the implemented 1-bit adders, we systematically synthesize multi-bit adders and multipliers proceeding from the least to the most significant bits. We design the ripple-carry adders such that their successive 1-bit approximate adders cannot produce build-up errors. We design the Wallace-tree multipliers by considering the fact that their building blocks of 1-bit adders might have different probabilities of occurrence for different input assignments. As a result, the proposed adders and multipliers, implemented using the Cadence Genus tool with TSMC 0.18μ m CMOS technology, offer in average a 25% smaller circuit area, and correspondingly power consumption, compared to the circuits proposed in the literature by satisfying the same error constraint. We also evaluate the adders and multipliers in image processing applications as well as within artificial neural networks.     

数字化语音减速保调播放插值算法及实现

对数字化语音减速保调播放问题进行了研究并提出了一种播值算法。实验表明,算法既保证了语音质量,又有良好的实时性。