Monday, April 23, 2007

MIT 6.002 2000 Lec 8

Dependent Sources and Amplifiers
Course Page
Lecture

REVIEW-
node method (covered in earlier lecture)
-works for linear and nonlinear circuits
small signal method
-focusing on small variation allows for linear approximation through nonlinear device

TODAY-
dependent sources
amplifiers

WHY AMPLIFY?
small input through amplifier gives large output

with 1mV signal and 10mV of noise, signal is hard to discriminate from noise
if 1mV signal is amplified to 100mV version of same signal, that noise will be less significant.
Cell phone example
-antennae signal is sent through Low Noise Amplifier immediately and then processed

AMPLIFICATION IN DIGITAL DOMAIN
digital system must use certain voltage thresholds to discriminate 1s from 0s
above Vih is 1 and below Vil is 0 for input
above Voh is 1 and below Vol is 0 for output
minimum amplification= (Voh - Vol)/(Vih - Vil)

A QUICK DETOUR
dependent source
-voltage across control ports defines output current for VCCS (voltage controlled current source)
-CCCS, VCVS, CCVS
Id=f(Vi)
output current from VCCS is some function of some applied Vi voltage source.

Bunch of examples done that can be seen in lecture...I will work on setting up notes with my tablet so I can draw diagrams.

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