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WelcomeSpecificaitons, Design & Development of smart silicon sensor systems Mayur Sarode Engineer at INCAS3 Assen, The Netherlands
About the workshop Smart Sensor Systems 2012 by Delft Institute of Microelectronics (DIMES) Lectures , demonstrations, visit to clean room at TU/Delft.
Lectures1. Silicon sensors: Applications and Future Perspectives by Paddy French, TU/Delft.2. Designing Smart Sensors and Smart Sensor Systems by Kofi Makinwa, TU/Delft.3. Measurement techniques for smart sensor systems by Gerard Meijer, TU/Delft.4. Calibration and Self-Calibration of Smart Sensors by Michiel A.P Pertijs, TU/Delft.5. Integrated Hall Magnetic sensors by Pavel Keijk EPFL Lausanne, Switzerland.6. Capacitive Sensors by Xiujin Li, TU/Delft.7. Smart temperature sensors by Gerard Meijer, TU/Delft.8. Optical Sensors Based on Photon Detection by Reinoud Wolffenbuttel , TU/Delft.9. Physical chemosensors by Michel Velekoop, TU/Vienna.10. Dynamic offset-cancellation techniques by Kofi Makinwa, TU/Delft.11. Precision Instrumentation Amplifiers by Johan Huijsing , TU/Delft.12. Universal asynchronous sensor interfaces by Gerard Meijer, TU/Delft.13. Implantable Smart Sensors for Advanced Medical Devices by Tim Dension, Medtronics14. Interface electronics and A/D converters by Frank Reidijk, Xensor Integrartion15. Introduction to CMOS-based DNA Microarrays by Jan Bosiersm Dalasa16. Energy harvesting Sensor Systems by Ruud Vullers
What are Smart sensors?Sensors ~“Smart sensor” o Low cost, Small size, Multi-sensing o Self-test, digital output, bus interface, RF, energy scaveningTransducers ~ self generating, modulatingMEMS + CMOS design ~ a smart sensor
Silicon SensorsMEMS sensors~good planar processing technologySilicon not the best in class!Package design & analog designSignal processing to compensate for silicon defects Radiant Photo diodes (CMOS image sensors, optical sensors) Chemical Thermal Resistors, transistors, ISFETS thermopiles DNA detector, chemeosensors (temperature, wind sensor) Electrical Resistors,capaci Mechanical tors, inductors, Magnetic Diaphram, (Capacitive Hall-plates, magFET’s, coil(micromachiened devices) (Hall sensors) sensors)
Silicon SensorsRadition Domain • P-N junction depletion layer • Shorter wavelentgth is absorbed by silicon • CCD’s, position sensors Mechanical Domain • can introduce self test • Pressure and accelerartion sensors Thermal domain • Silicon sensitive to temperature • Temperature and flow measurement Magnetic Domain• Based on Hall effect• Magnetic field measurement, current, rotation and position Chemical Domain • Physical chemeosensors
Smart Sensor Systems: System specs. On Silicon Output format Sensor bandwidth ~ 10 KHz Errors: offset, drift, noise, cross sensitivity, linearity, impedance, multipath Measurement techniques to solve these problems • nested chopping •Dynamic element matching •Auto calibration
Smart Sensor Systems: functionality Hardware General hybrid solution Sensing Signal A/D Bus Processor element Conditioning converter Intefacing Universal transducer interface One chip solution Software Data oSelf test in accelerometer Self testing evaluation Auto-Calibration oTransducer electronic data sheet (TEDS) oThree signal measurement Auto- identificaiton calibration
Reducing errors• Random, Systematic, multi-path error• Auto zeroing vs Chopping• Reduces 1/f noise , offset,
Autocalibration What is Mx ?? 100 Kg Mx Kg 5 Kg 55 Kg 25 Kg High accuracy ~high dynamic range Sense1 Rotating Resistors Sense2
Compensating for parasitic effects Cable and wire impedance Zs1 Zs3 YX Vforce Isense Yp1Iforce Vsense Yp2 ZX Zs2 Zs4 Low ohmic impedance ( current) High ohmic impedance ( voltage)Cross and parasitic effects Zp Cx Rp Rx Cp Yp Ix Vx Capacitve sensors resistive sensors Votlage generating sensors Current generating sensors (humdity sensors) (thermistors/photoresistors) (thermopiles/PH) (photo detectors) Use of additonal sensors Excitation signal, DC vs square vs sinusoidal vs pulsed, frequency
Smart sensor Systems: A/D converters Conventional system Analog Off the shelf Front processor A/D end converter Smart A/D conversion Period converter Tsense Treference Toffset Sensing element processorreference element MUX Offset element MUX S/H circuit capacitve control Quantization Digital filtering ΣΔ converter •Also used with resistive sensors
Universal Sensor InterfaceSystem SetupSensing, signal conditioning , A/D conversionUniversal interface for interfacing sensor element to the processor
Smart sensor systems designWind sensor design at TU/DelftSystem design~ sensor biasingDigitize early, modulation techniques for siliconlimitationsCharacteristicsoSlow, use dynamic techniquesoSmall output voltage, spreads, thermal balancingoThermal offset due to placementAuto-zeroing of comparator~ low thermopile output1.6 μm technology10 bit ΣΔ ADC .
Smart temperature Sensors Absolute temp sensors Thermistors( cheap, non linear, sensitive,-80 to 200 ºC Platinum resistors (expensive, stable, -260 to 1000 ºC) Thermocouple (reference junction and measurementJunctions Microcontroller Silicon Vbe ~ temperature On silicon chips Integrated thermistors1.Comparable to Pt resistors Sensor Interface2.Stress dependent3.Voltage dependent non linear behaviour Thermocouples1.No offset, no calibration Measuring absolute temperature. Smart Temperature Temperature Sensing Sensor elements
Smart tempearature SensorsDesign considerations Accuracy Triple point of water ~ defined fixed point Absolute accuracy vs drift Drift (1 mK ~ 10 mK) Cross sensitivity to mechanical stress accuracy noise andresolution Reduced to 100 mK with packaging Self heating Dynamic behaviour Thermal design considerations Long term stability
So how to design it? Problem statementMicrorganism detection in milk products.System level designCircuit level design DC DC Im Is Milk carton Milk carton Sensor