Extended Data Fig. 2: Weight-update requests and resulting net weight change observed during neural network training.
From: Equivalent-accuracy accelerated neural-network training using analogue memory
a–d, Simulation results based on MNIST 20-epoch simulations for the 2PCM + 3T1C cell with full CMOS variability and transfer polarity inversion (matched with the experimental results; a, b) and for the 2PCM cell (c, d). a, c, Correlation between the aggregate weight update across 16,000 training images (for 2PCM + 3T1C, this corresponds to two consecutive transfer intervals) and the total number of pulses applied to obtain this weight update. b, d, Correlation between the aggregate number of pulses and the total number of programming pulses applied. The points chosen for Fig. 3 (±100, 1,000 for 2PCM + 3T1C and ±10, 50 for 2PCM) represent typical values requested by the backpropagation algorithm. Insets show vertical cross-sections at \(\sum {\rm{\Delta }}W=0\), where the aggregate sum of all individual weight changes ΔW is zero (sum of pulses is zero).
