Luke Theogarajan
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View article: The Gaussian-Multinoulli Restricted Boltzmann Machine: A Potts Model Extension of the GRBM
The Gaussian-Multinoulli Restricted Boltzmann Machine: A Potts Model Extension of the GRBM Open
Many real-world tasks, from associative memory to symbolic reasoning, demand discrete, structured representations that standard continuous latent models struggle to express naturally. We introduce the Gaussian-Multinoulli Restricted Boltzm…
View article: CMOS Single-Photon Avalanche Diode Circuits for Probabilistic Computing
CMOS Single-Photon Avalanche Diode Circuits for Probabilistic Computing Open
Intrinsically random hardware devices are increasingly attracting attention for their potential use in probabilistic computing architectures. One such device is the single-photon avalanche diode (SPAD) and an associated functional unit, th…
View article: A Full-Stack View of Probabilistic Computing With p-Bits: Devices, Architectures, and Algorithms
A Full-Stack View of Probabilistic Computing With p-Bits: Devices, Architectures, and Algorithms Open
The transistor celebrated its 75th birthday in 2022. The continued scaling of the transistor defined by Moore’s law continues, albeit at a slower pace. Meanwhile, computing demands and energy consumption required by modern artificial intel…
View article: A full-stack view of probabilistic computing with p-bits: devices, architectures and algorithms
A full-stack view of probabilistic computing with p-bits: devices, architectures and algorithms Open
The transistor celebrated its 75${}^\text{th}$ birthday in 2022. The continued scaling of the transistor defined by Moore's Law continues, albeit at a slower pace. Meanwhile, computing demands and energy consumption required by modern arti…
View article: CMOS-compatible Ising and Potts Annealing Using SinglePhoton Avalanche Diodes
CMOS-compatible Ising and Potts Annealing Using SinglePhoton Avalanche Diodes Open
Massively parallel annealing processors may offer superior performance for a wide range of sampling and optimization problems. A key component dictating the size of these processors is the neuron update circuit, ideally implemented using s…
View article: CMOS-compatible Ising and Potts Annealing Using Single Photon Avalanche Diodes
CMOS-compatible Ising and Potts Annealing Using Single Photon Avalanche Diodes Open
Massively parallel annealing processors may offer superior performance for a wide range of sampling and optimization problems. A key component dictating the size of these processors is the neuron update circuit, ideally implemented using s…
View article: An Autonomous Molecular Bioluminescent Reporter (AMBER) for Voltage Imaging in Freely Moving Animals
An Autonomous Molecular Bioluminescent Reporter (AMBER) for Voltage Imaging in Freely Moving Animals Open
Genetically encoded reporters have greatly increased our understanding of biology. While fluorescent reporters have been widely used, photostability and phototoxicity have hindered their use in long‐term experiments. Bioluminescence overco…
View article: A 125$\mu$W 8kS/s Sub-pA Area-Efficient Current Sensing 45nm CMOS ADC for Biosensing
A 125$\mu$W 8kS/s Sub-pA Area-Efficient Current Sensing 45nm CMOS ADC for Biosensing Open
This paper presents a 125$\mu$W, area efficient (0.042mm2) 81dB DR, 8kS/s current sensing ADC in 45nm CMOS capable of sensing sub-pA currents. Our approach combines the transimpedance amplifier (TIA) and ADC into a unified structure by fol…
View article: A 125$μ$W 8kS/s Sub-pA Area-Efficient Current Sensing 45nm CMOS ADC for Biosensing
A 125$μ$W 8kS/s Sub-pA Area-Efficient Current Sensing 45nm CMOS ADC for Biosensing Open
This paper presents a 125$μ$W, area efficient (0.042mm2) 81dB DR, 8kS/s current sensing ADC in 45nm CMOS capable of sensing sub-pA currents. Our approach combines the transimpedance amplifier (TIA) and ADC into a unified structure by foldi…
View article: Fighting Fire with Fire: Superlattice Cooling of Silicon Hotspots to Reduce Global Cooling Requirements
Fighting Fire with Fire: Superlattice Cooling of Silicon Hotspots to Reduce Global Cooling Requirements Open
The running costs of data centers are dominated by the need to dissipate heat generated by thousands of server machines. Higher temperatures are undesirable as they lead to premature silicon wear-out; in fact, mean time to failure has been…
View article: An Autonomous Molecular Bioluminescent Reporter (AMBER) for voltage imaging in freely moving animals
An Autonomous Molecular Bioluminescent Reporter (AMBER) for voltage imaging in freely moving animals Open
1. Abstract Genetically encoded reporters have greatly increased our understanding of biology, especially in neuroscience. While fluorescent reporters have been widely used, photostability and phototoxicity have hindered their use in long-…
View article: Multi-wavelength selective crossbar switch
Multi-wavelength selective crossbar switch Open
Here we demonstrate an 8x4 multi-wavelength selective ring resonator based crossbar switch matrix implemented in a 220-nm silicon photonics foundry for interconnecting electronic packet switches in scalable data centers. This switch design…
View article: Orchestrating cells on a chip: Employing surface acoustic waves towards the formation of neural networks
Orchestrating cells on a chip: Employing surface acoustic waves towards the formation of neural networks Open
For the investigation of cell-cell interaction in general and for neural communication and future applications of neural networks, a controllable and well-defined network structure is crucial. We here propose the implementation of an acous…
View article: Heterodyne-based hybrid controller for wide dynamic range optoelectronic frequency synthesis
Heterodyne-based hybrid controller for wide dynamic range optoelectronic frequency synthesis Open
Chip scale optical frequency combs using microresonators can enable a wide variety of applications from metrology to telecommunications. While tremendous progress has been made in miniaturizing the optical components, sources of variabilit…
View article: An Integrated-Photonics Optical-Frequency Synthesizer
An Integrated-Photonics Optical-Frequency Synthesizer Open
Integrated-photonics microchips now enable a range of advanced functionalities for high-coherence applications such as data transmission, highly optimized physical sensors, and harnessing quantum states, but with cost, efficiency, and port…
View article: Correction: Corrigendum: A multiply-add engine with monolithically integrated 3D memristor crossbar/CMOS hybrid circuit
Correction: Corrigendum: A multiply-add engine with monolithically integrated 3D memristor crossbar/CMOS hybrid circuit Open
Scientific Reports 7: Article number: 42429; published online: 14 February 2017; updated: 27 July 2017. M. Payvand, A. Madhavan, A. Ghofrani and L. Theogarajan were omitted from the author list in the original version of this Article. This…
View article: Towards an Integrated-Photonics Optical-Frequency Synthesizer With <1 Hz Residual Frequency Noise
Towards an Integrated-Photonics Optical-Frequency Synthesizer With <1 Hz Residual Frequency Noise Open
We introduce an architecture for optical-frequency synthesis using photonic-chip frequency combs and a heterogeneously integrated CW laser. The Kerr dual-comb that we describe offers a microwave-optical link to discipline the laser to an R…
View article: Chip-scale optical resonator enabled synthesizer (CORES) miniature systems for optical frequency synthesis
Chip-scale optical resonator enabled synthesizer (CORES) miniature systems for optical frequency synthesis Open
An approach for a low-power chip-scale package is described, that provides a laser output with a programmable frequency across 50 nm of bandwidth centered at 1550 nm, and a resolution of one part in 10(14).