Variable Point: A Number Format for Area- and Energy-Efficient Multiplication of High-Dynamic-Range Numbers

TL;DR

This paper introduces a variable-point number format that enhances dynamic range coverage in digital VLSI designs, enabling more efficient high-dynamic-range signal processing with reduced area and power consumption.

Contribution

The paper proposes a novel variable-point number format that improves dynamic range coverage without significantly increasing hardware complexity, demonstrated through VLSI implementation.

Findings

Achieves 20% area savings in VLSI implementation.

Achieves 10% power savings in VLSI implementation.

Maintains performance comparable to fixed-point designs.

Abstract

Fixed-point number representation is commonly employed in digital VLSI designs that have stringent hardware efficiency constraints. However, fixed-point numbers cover a relatively small dynamic range for a given bitwidth. In contrast, floating-point numbers offer a larger dynamic range at the cost of increased hardware complexity. In this paper, we propose a novel number format called variable-point (VP). VP numbers cover a larger dynamic range than fixed-point numbers with similar bitwidth, without notably increasing hardware complexity -- this allows for a more efficient representation of signals with high dynamic range. To demonstrate the efficacy of the proposed VP number format, we consider a matrix-vector multiplication engine for spatial equalization in multi-antenna wireless communication systems involving high-dynamic-range signals. Through post-layout VLSI implementation results, we demonstrate that the proposed VP-based design achieves 20% and 10% area and power savings, respectively, compared to a fully optimized fixed-point design, without incurring any noticeable performance degradation.