Search for notes by fellow students, in your own course and all over the country.
Browse our notes for titles which look like what you need, you can preview any of the notes via a sample of the contents. After you're happy these are the notes you're after simply pop them into your shopping cart.
Title: ELECTRICAL ANALOGUE CIRCUIT
Description: • Review of op amp fundamentals • Op amp applications (non-linear) • Analog to Digital Converters (ADC) & Digital to Analog Converter (DAC) • (Linear) power supplies • Non-ideal behaviour of op amps & noise in analogue electronic systems
Description: • Review of op amp fundamentals • Op amp applications (non-linear) • Analog to Digital Converters (ADC) & Digital to Analog Converter (DAC) • (Linear) power supplies • Non-ideal behaviour of op amps & noise in analogue electronic systems
Document Preview
Extracts from the notes are below, to see the PDF you'll receive please use the links above
(SYSTEMS &)
ANALOGUE ELECTRONICS III
MODULE EE316
CREDIT RATING = 5
• Review of op amp fundamentals
• Op amp applications (non-linear)
• Analog to Digital Converters (ADC) & Digital to
Analog Converter (DAC)
• (Linear) power supplies
• Non-ideal behaviour of op amps & noise in analogue
electronic systems
Recommended Book
Design with Operational Amplifiers and Analog
Integrated Circuits
by Sergio Franco
published by McGraw Hill
• Selected chapters
• Restricted Loan in Library
Review of op amp fundamentals
2 ways of looking at an “amplifier”
1
...
• Power amp
...
• Transresistance amp
...
Energy modulator approach
Power supply
Vi
Control
Vo
Variations in the input (I/P) signal voltage cause
corresponding variations in the output (O/P) signal
voltage
This approach highlights fact that the electrical energy
delivered (even if in a
...
form) through O/P port to any
load is drawn from d
...
power supply (NOT from I/P
signal and NOT from nowhere)
Note: amp O/P port will have limited voltage AND
current capability (as will power supply)
”New” terminology:
Voltage amp
...
Current Controlled Current
Source CCCS
Transconductance amp
...
Current Controlled Voltage
Source CCVS
Op amps are designed to have close to ideal VCVS
characteristics
• Symbols
• Notation
• Model(s)
Symbol + notation:
Vn
Vo
Vp
Common
Reference
• Inverting and non-inverting I/Ps
• Some (arbitrary) common reference for voltages
Where does power supply come in?
• Op amps DO NOT (in general) have a common ref
(GND, common, 0V, etc) terminal or pin
• Only +ve & −ve (VCC & VEE in EE2)
VCC
Vn
Vp
Vo
VEE
Common
Ref
Using a single Power Supply Unit (PSU) (where is VCC
? & VEE ?)
• Free to choose ANY point as common ref
e
...
−ve terminal of PSU ⇒ VCC = Vsupply & VEE= 0V
VCC
Vsupply
Vn
VEE
Vp
Common
Ref
Vo
• More commonly we use dual PSUs balanced about a
central common ref which we then (generally) &
conveniently call:
0V or GND
• Measure / refer voltage (potential) of any/all points in
circuit w
...
t this point
VPS
VCC
Vn
Vp
VEE
Vo
Common = 0V = GND
Ref
⇒ VCC = +VPS & VEE= − VPS
Don’t usually draw all the elements!
VPS
Model:
ro
Vd
rd
aVd
Vn
Vo
Vp
Common
Reference
Other notation:
V−
Vn
V+
Vp
Vi '
Vd
AOL
a
AOL=open-loop gain
Designed to have:
• rd large
• ro small
• a large
Input currents
VCC
In
Ip
Vn
Vp
VEE
Vo
Common
Ref
Remember (EE2):
• op amp inputs are the bases of transistors
⇒ will have currents
• Designed to be small
Back to model:
• rd large
• ro small
• a large
• In small
• Ip small
Ideal Model:
• rd large → ∞
• ro small ≈ 0
• a large → ∞
• In = Ip ≈ 0
Vd
aVd
Vn
Vo
Vp
• Use for most analysis purposes
• Revert to non-ideal model for more exacting analysis
Ideal Behaviour
Noninverting Amp
R2
R1
VCC
VEE
Vi
Vo
0V
Use model (slightly modified)
Vp
Vn
Vd
aVd
Vi
Vo
R1
R2
Feedback
network
Voltage Follower:
VCC
VEE
Vi
Vo
0V
Model
Vp
Vn
Vd
aVd
Vi
Vo
Feedback
network
Inverting Amp
R2
R1
VCC
Vi
VE
Vo
0V
Model
Vp
Vn
Vd
aVd
Vo
R1
Vi
R2
Feedback
network
(High gain) Negative Feedback (NFB)
• a large and b > 0
e
...
for Non-Inv Amp
Vε
Vi
Vfb
a
b
Vfb
→
Vn
Vi
→
Vp
Vε
→
Vd
b
=
R1
R1 + R2
Vo
a
=
Closed Loop Gain , A =
Vi 1 + ab
ab = Loop Gain
Ideally a → ∞
⇒ Aideal
1
=
b
Ideal closed loop gain
Vo
Effect of NFB
Vε =
Vo
1
=
Vi
a 1 + ab
V fb = bVo =
ab
Vi
1 + ab
As a → ∞ : Vε → 0 and Vfb → Vi
⇒Virtual short between Inv and Non-inv I/Ps
(but with zero current also !)
Gain (de)Sensitivity:
A=
a
(1 + ab)
dA
1
=
da (1 + ab) 2
⇒
dA
1 da
=
A 1 + ab a
(or ∆ or 100∆)
Distortion:
Vo
Vo
Vi V
Vε µV
Slope = a
Reduction in distortion due to feedback
...
However, if we
insert the Voltage Follower between the source and the load, then
because Ri=∞ and Ro=0 for the voltage follower, the voltage across
the load is Vi
...
It reduces loading effect
...
g
...
models
Vo [V]
3
VSATH
VSATL
a
Vd [µV]
VSATH
2
1
a
VSATL
Region 2 (linear region): Slope = a
Vd
aVd
Vo
Regions 1 & 3 (lower and upper saturation regions)
3
1
Vd
VSATL
Vo
Vd
VSATH
Vo
Title: ELECTRICAL ANALOGUE CIRCUIT
Description: • Review of op amp fundamentals • Op amp applications (non-linear) • Analog to Digital Converters (ADC) & Digital to Analog Converter (DAC) • (Linear) power supplies • Non-ideal behaviour of op amps & noise in analogue electronic systems
Description: • Review of op amp fundamentals • Op amp applications (non-linear) • Analog to Digital Converters (ADC) & Digital to Analog Converter (DAC) • (Linear) power supplies • Non-ideal behaviour of op amps & noise in analogue electronic systems