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 1.Output voltage/current should be independent of Power Supply 2.Output voltage/current should be independent of temperature 3.Output voltage/current should be independent of process variations.

3. Sensitivity is a measure of dependence of V ref (I ref ) upon a parameter or variable x which influences V ref (I ref ). ; Where x could be V DD or temperature SENSITIVITY

4. Minimize the fractional Temperature Coefficient TEMPERATURE DEPENDANCE

5. BOOTSTRAPPED CURRENT SOURCE

11. V BE REFERENCE CURRENT SOURCE

13. Simple Voltage References Objective is to minimize Types of Voltage References: 1.Voltage Dividers – Active 2.MOS Diode Reference 3.PN Junction Diode Reference 4.Gate-Source Threshold Voltage Reference 5.Base-Emitter Reference Circuit

14. ACTIVE VOLTAGE DIVIDERS

15. PN JUNCTION VOLTAGE REFERENCE

16. V BE MULTIPLIER

17. PN JUNCTION

19. GATE SOURCE REFERENCE CIRCUIT

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

21. GATE SOURCE REFERENCE CIRCUIT

23. BANDGAP VOLTAGE REFERENCE

27. By taking the derivative at T 0 (assuming that J C has a temperature dependence of T α, the dependence of V BE with temperature is given by

31. CURVATURE CORRECTION ?

32. CORRECTION TOPOLOGY