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Unformatted text preview: Transconductance Example Gm = g m1
EE105, Fall 2013 Lecture 20 – Slide 15 Prof. Ming C. Wu MOS Cascode Ampliﬁer Av = −Gm Rout
Av ≈ − g m1 [(1 + g m 2 rO 2 )rO1 + rO 2 ]
Av ≈ − g m1rO1 g m 2 rO 2 EE105, Fall 2013 Lecture 20 – Slide 16 Prof. Ming C. Wu 8 PMOS Cascode Current Source as Load §༊ A large load impedance can be achieved by using a PMOS cascode current source. RoN ≈ g m 2 rO 2 rO1
RoP ≈ g m 3 rO 3 rO 4
Rout = RoN  RoP Lecture 20 – Slide 17 EE105, Fall 2013 Prof. Ming C. Wu MOS Current Mirror §༊ The moIvaIon behind a current mirror is to duplicate a (scaled version of the) “golden current” to other locaIons. Current mirror concept Generation of required VGS 1
⎛ྎ W ⎞ྏ
2
I REF = µnCox ⎜ྎ ⎟ྏ (VX − VTH )
2
⎝ྎ L ⎠ྏ REF
VX = EE105, Fall 2013 2 I REF
+ VTH 1
µ nCox (W / L )1
Lecture 20 – Slide 18 Current Mirror Circuitry I copy1 = 1
⎛ྎ W ⎞ྏ
µnCox ⎜ྎ ⎟ྏ (VX − VTH )2
2
⎝ྎ L ⎠...
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This note was uploaded on 01/22/2014 for the course EE 105 taught by Professor Kingliu during the Fall '07 term at University of California, Berkeley.
 Fall '07
 KingLiu
 Amplifier

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