WelcomeSpecificaitons, Design & Development of smart

silicon sensor systemsMayur Sarode

Engineer at INCAS3Assen, The Netherlands

About the workshop

Smart Sensor Systems 2012 by Delft Institute of Microelectronics (DIMES)

Lectures , demonstrations, visit to clean room at TU/Delft.

Lectures

1. 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,

Medtronics

14. Interface electronics and A/D converters by Frank Reidijk, Xensor Integrartion

15. Introduction to CMOS-based DNA Microarrays by Jan Bosiersm Dalasa

16. Energy harvesting Sensor Systems by Ruud Vullers

What are Smart sensors?

Sensors ~“Smart sensor”o Low cost, Small size, Multi-sensingo Self-test, digital output, bus interface, RF, energy scavening

Transducers ~ self generating, modulating MEMS + 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

ThermalResistors, transistors,

thermopiles(temperature, wind sensor)

MechanicalDiaphram,

(micromachiened devices)

Radiant Photo diodes

(CMOS image sensors, optical sensors)

MagneticHall-plates, magFET’s, coil

(Hall sensors)

ElectricalResistors,capacitors, inductors,

(Capacitive sensors)

ChemicalISFETS

DNA detector, chemeosensors

Silicon Sensors Radition 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

SoftwareoSelf test in accelerometerAuto-CalibrationoTransducer electronic data sheet (TEDS)oThree signal measurement

Sensing element

SignalConditioning

A/Dconverter

BusIntefacing

Processor

General hybrid solution

One chip solution

Universal transducer interface

Self testing Data evaluation

Auto-calibration identificaiton

Reducing errors• Random, Systematic, multi-path error• Auto zeroing vs Chopping

• Reduces 1/f noise , offset,

Autocalibration What is Mx ??

High accuracy ~high dynamic range

5 Kg

55 Kg

100 Kg

25 Kg

Mx Kg

Rotating Resistors

Sense1

Sense2

Compensating for parasitic effects

Cross and parasitic effects

Use of additonal sensorsExcitation signal, DC vs square vs sinusoidal vs pulsed, frequency

Zs1 Zs3

Zs2 Zs4

ZXIforce Vsense

Yp1 Y

p2

YX

Vforce Isense

Low ohmic impedance ( current) High ohmic impedance ( voltage)

Cable and wire impedance

Cx RpRx Cp

Zp

VxIx Yp

Capacitve sensors(humdity sensors)

resistive sensors (thermistors/photoresistors)

Votlage generating sensors(thermopiles/PH)

Current generating sensors(photo detectors)

Smart sensor Systems: A/D converters

Conventional system

Smart A/D conversion

AnalogFrontend

Off the shelfA/D

converter

processor

MUXcontrol

Period converter

processorSensing element reference element

Offset elementMUX

S/H circuitQuantizationDigital filteringΣΔ converter

capacitve

Tsense Treference Toffset

•Also used with resistive sensors

Universal Sensor Interface

System Setup

Sensing, signal conditioning , A/D conversionUniversal interface for interfacing sensor element to the processor

Smart sensor systems design

Wind sensor design at TU/Delft

System design~ sensor biasingDigitize early, modulation techniques for siliconlimitationsCharacteristics

oSlow, use dynamic techniquesoSmall output voltage, spreads, thermal balancingoThermal offset due to placement

Auto-zeroing of comparator~ low thermopile output1.6 μm technology10 bit ΣΔ ADC .

Smart temperature Sensors

Absolute temp sensorsThermistors( cheap, non linear, sensitive,

-80 to 200 ºCPlatinum resistors (expensive, stable, -260 to 1000 ºC)Thermocouple (reference junction and measurement

JunctionsSilicon Vbe ~ temperature

On silicon chipsIntegrated thermistors

1.Comparable to Pt resistors2.Stress dependent3.Voltage dependent non linear behaviour

Thermocouples1.No offset, no calibration

Measuring absolute temperature.

Microcontroller

Sensor Interface

Smart Temperature

Sensor

Temperature Sensingelements

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 and resolution Reduced to 100 mK with packaging

Self heating

Dynamic behaviour Thermal design considerations Long term stability

So how to design it? Problem statement

Microrganism detection in milk products.

System level design

Circuit level design

DC DC

Milk carton

Im Is

Sensor Milk carton

Conclusions

Thank you