Presentation on theme: "Neuromorphic Analog VLSI West Virginia University"— Presentation transcript:
1 Neuromorphic Analog VLSI West Virginia University David W. GrahamWest Virginia UniversityLane Department of Computer Science and Electrical Engineering
2 Neuromorphic Analog VLSI Each word has meaningNeuromorphicAnalogVLSI
3 Engineering Versus Biology Core 2 Duo65 watts291 million transistors>200nW/transistorBrain10 watts>100 billion neurons~100pW/neuron
4 Neuromorphic/Bio-Mimetic Engineering Neuromorphic/Bio-Mimetic Engineering – Using biology to inspire better engineeringHigh-quality processingLow power consumptionSensorimotor SystemsIntelligent roboticsIntelligent controlsLocomotive systemsNeuronsSystems that learnSystems that adaptNeural networksUnderstanding biologySilicon RetinaCMOS imagersIntelligent imagersRetinal implantsElectronic Nose“Sniff out” odorsChemical sensorsDrug traffic controlBio terror detectionAudio SystemsAudio front endsSignal processing systemsHearing aidsCochlear implants
5 Why Neuromorphic Engineering? Interest in exploringneuroscienceInterest in buildingneurally inspired systemsKey AdvantagesThe dynamics is the systemWhat if our primitive gates were a neuron computation?a synapse computation? a piece of dendritic cable?Efficient implementations compute in their memory elements– more efficient than directly reading all the coefficientsPrecise systems out of imprecise parts
6 Biology and Silicon Devices Similar physics of biological channels and p-n junctionsExponential distribution of particles(Ions in biology and electrons/holes in silicon)Drift and Diffusion equations form a built-in Barrier(Vbi versus Nernst Potential)Both biological channels and transistors have agating mechanism that modulates a channel.
8 Neuromorphic Products Neuromorphic Engineering is a relatively young field. However, it is already producing some very popular products.Logitech TrackballB.I.O.-Bugs and RobosapienNeuromorphic Engineering is also helping to advance the field of neuroscience.
9 Where Can We Go? Bio-Inspired Systems Smart Embedded Low-Power Analog SensorsHearing AidsCochlear ImplantsLow-Power AnalogConsumer ElectronicsImplantable DevicesSubthreshold DesignAnalog ProgrammabilityProvides digital features to the analog domainProgrammabilityAccuracyReconfigurability“Silicon Simulation”Analog alleviates the burden of the digitalPowerful Mixed-Signal Systems
10 Why Analog? Much lower power than digital Can perform many computations faster and more efficiently than digitalFollows the same physical laws as biological systems
11 FFT vs. Analog Cochlear Model Analog Power Savings19823YearPogmblAnwSvis>LpTchy.WG'DCPower Dissipated / MMACGene’s LawPower consumption of integrated circuits decreases exponentially over timeFollows Moore’s LawAnalog computation yields tremendous power savings equal to a >20 year leap in technologyFFT vs. Analog Cochlear Model32 subbands at 44.1kHzFFT consumes ~5mW (audio-streamlined DSP)Analog consumes <5μWAnalog power savings of >1000
12 Why VLSI? Cheaper (and easier to mass produce) Smaller Reduces power Keeps everything containedReduces noiseReduces coupling from the environmentNeed a large number of transistors to perform real-world computations/tasksAllows a high density or circuit elements (therefore, VLSI reduces costs)
13 Difference Between Discrete and VLSI Design Analog VLSIDiscrete AnalogDevice Size and ValuesRelatively Smallex. Capacitors 10fF-10pFLargeex. Capacitors 100pF-100μFResistorsMostly badVery expensive (large real estate)Easy to UseCheapInductorsOnly feasible for very high frequenciesExtremely expensiveUse when neededParasiticsVery big concernSeriously alter system performanceExist, but rarely affect performance(Large size of devices and currents)MatchingDifficult to deal withMajor concernStuck with whatever was fabricatedex. 50% mismatch is not uncommonConcernCan more easily match/replacePowerEfficient(Small currents pA-mA)Use more power(Large currents >mA)
14 To Summarize … Good Things about Analog VLSI Inexpensive Compact Power EfficientNot So Good Things about Analog VLSI (not necessarily bad)Limited to transistors and capacitors (and sometimes resistors if a very good reason)Parasitics and device mismatch are big concernsYou are stuck with what you built/fabricated (no swapping parts out)However, Neuromorphic Analog VLSI is all about how to cope with these “problems,” how to get around them, and how to use them as an advantage
15 Important Considerations We will limit our discussion to CMOS technologiesNo BJTsOnly MOSFETsTherefore, we will discuss only silicon processes
16 Every story has a beginning… Looking at connectionswith neurobiologyBegin at MOS device physicsLook at circuits using the device propertiesBuilding small systems from circuits