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REFERENCE CIRCUITS What is a Reference Circuit?
A reference circuit is an independent voltage or current source which has a high degree of precision and stability Requirements for 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 processing variations
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V-I Characteristics of an Ideal Reference
Voltage Reference Iref Current Reference Vref v
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Concept of Sensitivity
Definition Sensitivity (S) is a measure of dependence of Vref (Iref) upon a parameter or variable x which influences Vref (Iref). For example, if the sensitivity is 1, then a 10% change in x will cause a 10% change in Vref. Ideally, SVREFX(VDD,Temp)0
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Types of references 1. Voltage dividers - passive and active.
1. Voltage dividers - passive and active. 2. MOS diode reference. 3. PN junction diode reference. 4. Gate-source threshold referenced circuit. 5. Base-emitter referenced circuit.
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Targil Kita. Estimate accuracy and sensitivity to power for the following Passive & Active Voltage References
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PN_Junction Voltage reference and MOS Equivalent (Gate source)
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Targil Kita II. What is the Voltage Reference of the PN junction and MOS equivalent circuits? How can we modify these Voltages?
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Bootstrapped Current Source
Vgs?, Iout?
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