Download ppt

ENGS2613 Intro Electrical Science
Week #9
Dr. George Scheets



Read 6.1 & 6.2
Problems 5.36, 5.37, 5.39 , 5.40, 5.42, & 6.1
Quiz 5 on Friday, 21 October, OpAmps
Op Amps: Output Load
-
vin(t)
Av
+

Rload
Ideally, load does not effect characteristics
 Ideal

vout(t)
OpAmp can source or sink any current
Practically, load may effect characteristics
 If
real OpAmp output can't source or sink
enough current
Good Opamp Circuit #1
α
Io = α/R amps
Vin = Fixed at α volts?
This is an independent
current source
source: Horowitz & Hill, THE ART OF ELECTRONICS, 1990
Good Opamp Circuit #1
Vin
Io = Vin/R amps
Vin = Changeable?
This is a voltage controlled
dependent current source
source: Horowitz & Hill, THE ART OF ELECTRONICS, 1990
Inductors
Resists Change in
Current
source: coilwindingmachines.eu, hamradioschool.com,
Transformers

Inductively couple input signal to output
Source: wikipedia, tradindia.com
High Frequency Chokes

Used in series with a current flow
 Suppress
rapidly varying signals
Inductors
Can store energy in magnetic field
Tries to resist changes in the current
Short Circuit if DC input
 v = L di/dt (Units of L are Ω*second)

t

i(t) - i(0-) = 1
L
∫ v dt
0
Henry
Joseph Henry
1797 – 1878
 American Professor

 Albany

Academy
Discovered Principles of
Induction ≈ Simultaneous
with Faraday
 Faraday

Published First
1 volt =
(1 Henry)(1 Amp/sec)
Source: Wikipedia
Inductors
Michael Faraday
1791 – 1867
 English Physicist
 1830 - 1831
Discovered Principles of
Induction
 Units of Capacitance,
Farad, Named After
Faraday

Source: Wikipedia
Wireless Charging


Works via Inductive Coupling
v = L di/dt
v
= Voltage generated in Receiver Coil
 L = Mutual Inductance
 di/dt = time rate of current change in the Transmitter Coil

Note: Higher frequencies generate a higher voltage.
Source:
powerbyproxi.com
Integrated Circuits

Inside are mostly
very tiny
 Transistors
 Resistors
 Capacitors
Can Often Use C or L

DC Block
 Want
to block DC voltage from output
C
Vdc + vsignal
vsignal
Rload
R
vsignal
Vdc + vsignal
L
Rload
Can Often Use C or L

DC Power Supply Filter
 Want
to constant voltage on output
L
Vdc + vnoise
Rload
Vdc
R
Vdc
Vdc + vnoise
C
Rload
Inductors vs Capacitor


Inductor
Short Circuit if DC in
v = L di/dt


Capacitor
Open Circuit if DC in
i = C dv/dt
t
t

∫
i(t) - i(0-) = 1
v dt
L 0

∫
v(t) - v(0-) = 1
i dt
C 0