1,842 research outputs found
An integrated capacitance bridge for high-resolution, wide temperature range quantum capacitance measurements
We have developed a highly-sensitive integrated capacitance bridge for
quantum capacitance measurements. Our bridge, based on a GaAs HEMT amplifier,
delivers attofarad (aF) resolution using a small AC excitation at or below kT
over a broad temperature range (4K-300K). We have achieved a resolution at room
temperature of 10aF per root Hz for a 10mV AC excitation at 17.5 kHz, with
improved resolution at cryogenic temperatures, for the same excitation
amplitude. We demonstrate the performance of our capacitance bridge by
measuring the quantum capacitance of top-gated graphene devices and comparing
against results obtained with the highest resolution commercially-available
capacitance measurement bridge. Under identical test conditions, our bridge
exceeds the resolution of the commercial tool by up to several orders of
magnitude.Comment: (1)AH and JAS contributed equally to this work. 6 pages, 5 figure
Neural Network Compression for Noisy Storage Devices
Compression and efficient storage of neural network (NN) parameters is
critical for applications that run on resource-constrained devices. Although NN
model compression has made significant progress, there has been considerably
less investigation in the actual physical storage of NN parameters.
Conventionally, model compression and physical storage are decoupled, as
digital storage media with error correcting codes (ECCs) provide robust
error-free storage. This decoupled approach is inefficient, as it forces the
storage to treat each bit of the compressed model equally, and to dedicate the
same amount of resources to each bit. We propose a radically different approach
that: (i) employs analog memories to maximize the capacity of each memory cell,
and (ii) jointly optimizes model compression and physical storage to maximize
memory utility. We investigate the challenges of analog storage by studying
model storage on phase change memory (PCM) arrays and develop a variety of
robust coding strategies for NN model storage. We demonstrate the efficacy of
our approach on MNIST, CIFAR-10 and ImageNet datasets for both existing and
novel compression methods. Compared to conventional error-free digital storage,
our method has the potential to reduce the memory size by one order of
magnitude, without significantly compromising the stored model's accuracy.Comment: 19 pages, 9 figure
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