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U nited A rab E mirates U niversity C ollege of E ngineering E lectrical E ngineering D epartment

U nited A rab E mirates U niversity C ollege of E ngineering E lectrical E ngineering D epartment. Graduation Project 2 Design of a CMOS voltage reference Coordinator: Dr. Mohammed Younis Under Dr. Adnan Harb supervision. Group members: Marwa Nabil 200235370

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U nited A rab E mirates U niversity C ollege of E ngineering E lectrical E ngineering D epartment

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  1. United Arab Emirates University College of Engineering Electrical Engineering Department Graduation Project 2 Design of a CMOS voltage referenceCoordinator: Dr. Mohammed YounisUnder Dr. AdnanHarb supervision Group members: MarwaNabil 200235370 NooraMazrooei 200309851 Samira Elmi 200337929 ShaymaOsman 200337070

  2. Agenda • Introduction • Completed tasks in GPI • Calculations • Simulation and Results • Layout Design • DRC & LVS • Environmental, standard and cost • Conclusion

  3. Introduction • A voltage reference is an electronic circuit that produces a fixed voltage with minimum effect • Temperature • Power supply • This circuit is the key for functioning several electronic devices • e.g. : A/D and D/A converters

  4. Completed work  done  in GPI Comparison between different designs

  5. The Choice • The choice: • Voltage Reference using Subthreshold MOSFETs • Reasons: • Experimental measurement • Medium power consumption • Simple

  6. Porting Sub-threshold design • Functionality and Connectivity test • 0.35 μm CMOS technology • Power supply voltage = 3.3 V • All components with same sizes ( to be optimized in GP2)

  7. Preliminary Results

  8. 251mV I=3.24 µA Power 10.7 µW <1%decrease of Vref I=3.2 µA Power 3.7 µW • The output Voltage reference as function of the power supply voltage

  9. Calculations • PMOS • Assumption: ID = 0.6 µA VGS = -0.725V • Transistors’ Size: • NMOS • Assumption: ID = 0.6 µA VGS = 0.45V

  10. Calculations • Bias current (IB) was calculated using this equation: • RP=100KΩ, • IB=0.6µA. • Mp6 & Mp7 values were the same as those used in the article and they were used to make up the startup the bias current circuit.

  11. Calculations • Resistors and capacitors • Nullifying the temperature coefficient of voltage reference. KG was calculated and it is equal to -0.65.

  12. Calculations • The capacitors values are shown below and they were used to minimize the ripple and get a constant Vdcat the output

  13. Simulation and Results

  14. Simulation and Results

  15. Simulation and Results Temperature co-efficient:

  16. Simulation and Results Power supply and temperature effect: • The effect of both temperature and power supply on the voltage reference value: at 1.2V, ∆VRef =4.07 mv.

  17. Simulation and Results • Comparison

  18. Layout Design • Voltage reference layout

  19. Bias current layout

  20. The Complete Circuit

  21. Environmental, standard and cost • Ethical issues have been considered in this project • References • Environmental issues is considered in the fabrication (out of scope of our project). • Safety considerations • Societal impacts • The budget cost of the project is 2500 AED as it costs to buy the test fixture

  22. Conclusion • New concepts were introduced such as: • Voltage reference • Current mirror • Sub-threshold voltage. • Skills related to analog IC design were gained . • Problems faced in designing integrated circuits.

  23. Thank you for your attention ?

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