Design of a Low-Power Analog Integrated Deep Convolutional Neural Network

In this article, a framework for the analog implementation of a deep convolutional neural network (CNN) is introduced and used to derive a new circuit architecture which is composed of an improved analog multiplier and circuit blocks implementing the ReLU activation function and the argmax operator. The operating principles of the individual blocks, as well as those of the complete architecture, are analyzed and used to realize a low-power analog classifier, consuming less than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.8~\mu \text {W}$</tex-math> </inline-formula>. The proper operation of the classifier is verified via a comparison with a software equivalent implementation and its performance is evaluated against existing circuit architectures. The proposed architecture is implemented in a TSMC 90-nm CMOS process and simulated using Cadence IC Suite for both schematic and layout design. Corner and Monte Carlo mismatch simulations of the schematic and the physical circuit (postlayout) were conducted to evaluate the effect of transistor mismatches and process voltage temperature (PVT) variations and to showcase a proposed systematic method for offsetting their effect.