Embedded Systems Analog Electronics - Laboratory for Perceptual ...

loutclankedΤεχνίτη Νοημοσύνη και Ρομποτική

13 Νοε 2013 (πριν από 3 χρόνια και 10 μήνες)

74 εμφανίσεις

Laboratory for Perceptual Robotics


Department of Computer Science

Embedded Systems

Operational Amplifiers

Laboratory for Perceptual Robotics


Department of Computer Science

OpAmps

…very high gain dc
-
coupled differential amplifiers

with single
-
ended outputs…

-
15V

non
-
invert

invert

offset null

NC

+15V

out

offset null

about $0.60 a piece

24 transistors

11 resistors


1 capacitor


amplifier gains ~ 10
5
-
10
6

Laboratory for Perceptual Robotics


Department of Computer Science

OpAmps

output ~ K (V
+

-

V
-
)

K ~ 10
6

V
+

V
-

+15V

-
15V

1.
output swings
dramatically

and via
feedback
, makes difference
between the inputs go to zero

2.
inputs draw no current (10
-
9
A)

a few millivolts difference between

inputs will cause the output to swing

full range

Laboratory for Perceptual Robotics


Department of Computer Science

OpAmps

V
out
= K (V
+

-

V
-
)

V
+

V
-

What does it mean to say the op amp is stable?

stable or unstable?

Laboratory for Perceptual Robotics


Department of Computer Science

OpAmps

What does it mean to say the op amp is stable?

V
out
= K (V
+

-

V
-
)

V
+

V
-

stable or unstable?

Laboratory for Perceptual Robotics


Department of Computer Science

OpAmps
-

Negative Feedback

feedback
-

comparing the output of a system to the desired
output in order to make a signed corrective action

CYBERNETICS

negative feedback
-

connect the output back to the input in such a
way as to cancel some of the input.

Harold S. Black
-

patent application on negative

feedback in 1928 was “…treated in the same manner as
one for a perpetual motion machine.”

Laboratory for Perceptual Robotics


Department of Computer Science

OpAmps
-

Stable Inverting Amplifier

assume V
+
=V
-
=GND

I
2

I
1

I
1
+I
2

= 0

note: low input and output impedance, R
1
+R
2

Laboratory for Perceptual Robotics


Department of Computer Science

OpAmps
-

Stable Non
-
Inverting Amplifier

assume V
+
=V
-
=GND

large input impedance

Z
in

~ 10
8

W

Laboratory for Perceptual Robotics


Department of Computer Science

OpAmps
-

Unity Gain Follower

Laboratory for Perceptual Robotics


Department of Computer Science

OpAmps
-

Current
-
to
-
Voltage Converter

Laboratory for Perceptual Robotics


Department of Computer Science

OpAmps
-

Summing Amplifier

weighted sum?

digital to analog converter?

Laboratory for Perceptual Robotics


Department of Computer Science

OpAmps
-

Bipolar Power Amplifier