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REFERENCE CIRCUITS

REFERENCE CIRCUITS. A Reference Circuit is an independent voltage or current source which has a high degree of precision and stability. Requirements of a Reference Circuit Output voltage/current should be independent of Power Supply Output voltage/current should be independent of temperature

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REFERENCE CIRCUITS

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  1. REFERENCE CIRCUITS A Reference Circuit is an independent voltage or current source which has a high degree of precision and stability. • Requirements of a Reference Circuit • Output voltage/current should be independent of Power Supply • Output voltage/current should be independent of temperature • Output voltage/current should be independent of process variations.

  2. SENSITIVITY Sensitivity is a measure of dependence of Vref (Iref) upon a parameter or variable x which influences Vref (Iref). ; Where x could be VDD or temperature

  3. TEMPERATURE DEPENDANCE Minimize the fractional Temperature Coefficient

  4. BOOTSTRAPPED CURRENT SOURCE

  5. VBE REFERENCE CURRENT SOURCE

  6. Simple Voltage References Objective is to minimize • Types of Voltage References: • Voltage Dividers – Active • MOS Diode Reference • PN Junction Diode Reference • Gate-Source Threshold Voltage Reference • Base-Emitter Reference Circuit

  7. ACTIVE VOLTAGE DIVIDERS

  8. PN JUNCTION VOLTAGE REFERENCE

  9. VBE MULTIPLIER

  10. PN JUNCTION

  11. GATE SOURCE REFERENCE CIRCUIT

  12. GATE SOURCE VOLTAGE FOR CONSTANT CURRENT (STRONG INVERSION)

  13. GATE SOURCE REFERENCE CIRCUIT

  14. BANDGAP VOLTAGE REFERENCE

  15. By taking the derivative at T0 (assuming that JC has a temperature dependence of Tα , the dependence of VBE withtemperature is given by

  16. CURVATURE CORRECTION ?

  17. CORRECTION TOPOLOGY

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