14_Lecutre

14_Lecutre - EE114 Lecture 14 Lecture 14 Supply Insensitive...

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EE114 Lecture 14 R. Dutton, B. Murmann 1 EE114 (HO #18) Lecture 14 Supply Insensitive Bias Current Generation R. Dutton, B. Murmann Stanford University R. Dutton, B. Murmann 2 EE114 (HO #18) Poor Man's Bias Issue: Current is essentially proportional to V DD – E.g. if V DD varies by X%, bias current will roughly vary by the same amount R V V V I I OV t DD IN OUT ! ! = "
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EE114 Lecture 14 R. Dutton, B. Murmann 3 EE114 (HO #18) "V t " Referenced Bias By using a sufficiently large device, we can make V OV < V t, and achieve 2 ox IN t 2 OV t 2 1 GS OUT R L W C I 2 V R V V R V I μ + ! + ! = 2 t OUT R V I ! Question: By how much will I OUT change given some variation in V DD ? R. Dutton, B. Murmann 4 EE114 (HO #18) Sensitivity The sensitivity of a parameter y to a change in parameter x can be approximately found using y x ! S x y y x x / x y / y x / x y / y = ! ! = ! ! " # In our case, we are looking for % . V . V . V . . g . e V V V I I I I S S S OV t OV IN OUT OUT IN I I I V I V OUT IN IN DD OUT DD 5 11 15 0 5 0 15 0 2 1 2 1 1 1 1 = + + ! " " # # ! # = Not bad, but also not all that great…
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EE114 Lecture 14 R. Dutton, B. Murmann 5 EE114 (HO #18) Self Biasing In the circuit discussed on the previous slides, the supply
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This note was uploaded on 11/02/2011 for the course EE 114 taught by Professor Murmann during the Fall '08 term at Stanford.

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14_Lecutre - EE114 Lecture 14 Lecture 14 Supply Insensitive...

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