A Convoluted Journey from CMOS to Spin Waves

In recent years, Spin Waves (SWs) have emerged as a promising CMOS alternative technology, and SW interference-based majority gates have been proposed and experimentally realized. In this paper, we pursue a different computation avenue and introduce a SW device able to evaluate 2×2 2D convolution, which is a fundamental element for the implementation of Convolutional Neural Networks (CNNs). Assuming that the window pixels are P = [p<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</inf>, p<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>; p<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf>, p<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf>] and the kernel is K = [k<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</inf>, k<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>; k<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf>, k<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf>] we introduce a device which evaluates the convolution result $\sum\nolimits_{i = 1}^4 {{p_i}} {k_i}$ within the SW domain by leveraging SWs inherent mechanisms, i.e., information encoding in SW amplitude and phase, SW amplitude decay due to Gilbert damping, SW interference. After introducing the SW device structure we demonstrate its proper behaviour by means of micromagnetic simulations. We also present power consumption, area, and delay estimates and argue that due to the fact that our proposal does not rely on standard adders and multipliers, it can substantially outperform traditional CMOS-based convolution implementations.