1. Design and optimization of Schottky diodes in CMOS technology with application to passive RFID systems Auto-ID lab Adelaide

2. Overview Introduction. Design and layout of Schottky diode. Modelling of designed SBD. Applications. Fabrication and measurements. Conclusion.

3. The General RFID Idea Normally a very weak reply is obtained The black spot

4. Example Applications What can you do with this technology ? Supply chain benefits – Reduce out of stocks, reduce inventory, speed up delivery, check freshness, track and trace, produce to demand, identify sources of diversion, identify counterfeiting, theft prediction, faster recalls Consumer benefits – Direct order from home, smart appliances, (e.g. microwave, washing machine, refrigerator), smart healthcare, assisted living New and less expected benefits – Customized products, smart recycling, checkout-less stores

5. Passive RFID RFID tag chip in standard CMOS technology. Low size. Low cost. Integration with existing logics and other modules. Supply sufficient operating power Metal directly deposited on N-Well. Titanium-Silicon/Tungsten-Silicon contact Functional but needs more improvements. Fabricated through MOSIS

6. Cross Sectional view of SBD Design a diode structure to minimize series resistance of n-well.

7. Cross Sectional view of SBD

8. Equivalent circuit

9. Multi-finger Schottky contact Reducing the series resistance Increasing the perimeter Decrease junction capacitance

10. Prototyped SBD sizes No Area(squar e Pico- meter Perimeter (Micro-meter) Fingers Contact Dimension (um*um) SD10.231.9210.48x0.48 SD20.231.9210.48x0.48 SD31.497.2010.48x3.12 SD416.1272.9060.48x5.6 SD514.460.9610.48x0.30

11. RFID Ant Model & Matching Start from dipole antenna model Use the model from “Modeling And Simulation of A Dipole Antenna for UWB Applications using equivalent spice circuits” John F.M. Gerrits, etc. Centre Suisse d'Electronique et de Microtechnique SA (CSEM) Neuchâtel – SWITZERLAND

12. Matching and Optimal Input Level Equivalent circuit of RFID chip Vrx value for 73  (half wavelength dipole) radiation resistance at 150uW input 50  resistor voltage swing

13. Matching and Optimal Input Level (Cont.) Quality factor of the RFID circuit (Serial configuration) Maximum voltage swing across the RFID chip 150uW input would have a 0.7V Vp-p input No other rectifier structure will work except Schottky diode rectifier structure Hard to decrease the input capacitance to increase the Q

14. Rectifier circuit (SBD application)

15. SBD Rectifier layout

16. Measurement Plan Discrete SBD test GSD probing pads for de-embedding S parameters DC parameters SBD rectifier test Input impedance Matching circuit/board Antenna Reader/Signal generator and PA+Antenna; Optimised tag

17. Discrete SBD Test

18. Prototype Reader

19. Future Work Test and extract the model parameters Validating the SBD model Improve the quality factor of the SBD Increase reverse direction breakdown voltage by guard ring (fabricated version dose not have) Improve efficiency by reducing parasitic capacitance Better impedance matching capabilities

20. Q&A Thank You