EE 435 Lect 21 Spring 2010

EE 435 Lect 21 Spring 2010 - EE 435 Lecture 21 Linearity in...

Info iconThis preview shows pages 1–12. Sign up to view the full content.

View Full Document Right Arrow Icon
EE 435 Lecture 21 Linearity in Basic Gain Stages Offset Voltages
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
How linear is the amplifier ? EB1 V 2 .• • • Review from last lecture .•
Background image of page 2
-0.2 -0.1 0 0.1 0.2 Signal Swing and Linearity of Bipolar Differential Pair .• • • Review from last lecture .•
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Applications as a programmable OTA ABC The current-dependence of the gm of the differential pair is often used to program the transconductance of an OTA with the tail bias current I ABC MOS m ABC OX W g = I 2uC L mO X E B W g= u C V L Two decade change in current for every decade change in g m One decade decrease in signal swing for every decade decrease in g m BJT ABC m t I V One decade change in current for every decade change in g m No change in signal swing when g m Is changed Limited g m adjustment possibility Large g m adjustment possible .• • • Review from last lecture .•
Background image of page 4
Linearity of Common-Source Amplifier SS DD V iS OUT B For convenience, will consider situation where current source biasing Is ideal .• • • Review from last lecture .•
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Linearity of Common-Source Amplifier SS DD V iS OUT B 2 1 12 iS iS BB OS SS OQ 22 EB EB EB EB II V- V λ VV β V λβ V ⎡⎤ ⎛⎞ ⎜⎟ ⎢⎥ ≅+ + ⎝⎠ ⎣⎦ V 2 1 2 iS iS OS EB EB - λ V λ V V 1 2 OS iS iS EB EB 2 - λ V2 V V Is this a linear or nonlinear relationship? .• • • Review from last lecture .•
Background image of page 6
Linearity of Common-Source Amplifier SS DD V iS OUT B 1 2 OS iS iS EB EB 2 λ V2 V ⎛⎞ ≅+ ⎜⎟ ⎝⎠ VV V Is this a linear or nonlinear relationship? when V iS = -V EB (the minimum value of V iS to maintain saturation operation) the error in V OS will be V EB /2 which is -50% ! Is this a linear or nonlinear relationship? -40 -30 -20 -10 0 10 20 30 -1 -0.5 0 0.5 1 Fit Line
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
-40 -30 -20 -10 0 10 20 30 -1 -0.5 0 0.5 1 Linearity of Common-Source Amplifier SS DD V iS OUT B 1 2 OS iS iS EB EB 2 - λ V2 V ⎛⎞ ≅+ ⎜⎟ ⎝⎠ VV V Is this a linear or nonlinear relationship? Over what output voltage range are we interested? Note this is a high gain amplifier
Background image of page 8
-40 -30 -20 -10 0 10 20 30 -1 -0.5 0 0.5 1 Linearity of Common-Source Amplifier SS DD V iS OUT B 1 2 OS iS iS EB EB 2 - λ V2 V ⎛⎞ ≅+ ⎜⎟ ⎝⎠ VV V Is this a linear or nonlinear relationship? Linearity is reasonably good over practical input range Practical input range is much less than V EB -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 -0.1 -0.05 0 0.05 0.1 Fit Line
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Linearity of Common-Source Amplifier SS DD V iS OUT B 1 2 OS iS iS EB EB 2 - λ V2 V ⎛⎞ ≅+ ⎜⎟ ⎝⎠ VV V Is this a linear or nonlinear relationship? -5 -4 -3 -2 -1 0 1 2 3 4 5 -0.025 -0.02 -0.015 -0.01 -0.005 0 0.005 0.01 0.015 0.02 0.025 Fit Line Can’t see nonlinearity in this plot
Background image of page 10
-5 -4 -3 -2 -1 0 1 2 3 4 5 -0.025 -0.02 -0.015 -0.01 -0.005 0 0.005 0.01 0.015 0.02 0.025 Linearity of Common-Source Amplifier SS DD V iS OUT B 1 2 OS iS iS EB EB 2 - λ V2 V ⎛⎞ ≅+ ⎜⎟ ⎝⎠ VV V Is this a linear or nonlinear relationship?
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 12
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 01/31/2012 for the course EE 345 taught by Professor Geiger during the Fall '11 term at Iowa State.

Page1 / 42

EE 435 Lect 21 Spring 2010 - EE 435 Lecture 21 Linearity in...

This preview shows document pages 1 - 12. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online