Dr. Bonnie H. FerriProfessor and Associate ChairSchool of Electrical and Computer Engineering

School of Electrical and Computer Engineering

Introduction to Electronics

An introduction to electronic circuit components and a study of circuits containing such devices.

Dr. Bonnie H. FerriProfessor and Associate ChairSchool of Electrical and Computer Engineering

School of Electrical and Computer Engineering

Active Filters

Introduce active filters and show different types of filters

Introduced differentiator and integrator op amp circuits

Previous Lesson

3

Introduce active filter circuits

Lesson Objectives

4

Analog Filters

Analog FilterVin Vout

0 0.05 0.1 0.15 0.2 0.25-2

-1

0

1

2

Time (sec)

v(t)

0 0.05 0.1 0.15 0.2 0.25-1.5

-1

-0.5

0

0.5

1

1.5

Time (sec)

v(t)

0 200 400 600 800 10000

0.2

0.4

0.6

0.8

1

Mag

nitu

de

H()

|H()|

(rad/sec)5

Quiz

Vin = 1 + cos(10(2t)) + cos(100(2t)) Vout = 0.45cos(10(2t)+1) + 0.97cos(100(2t) +2)

6

Summary of RC and RLC (Passive) Filters

vinR +

-voC

vin

R +

-vo

CL

vin R+

-vo

C

Mag

nitu

de (d

B)

Bode Plots

Mag

nitu

de (d

B)

Mag

nitu

de (d

B)

7

Depletes power

No isolation

Limitations of RLC Passive Filters

Analog FilterVin Vo

vinR +

-voC

8

has its own power supply Most common active filters are made from op amps Provide isolation

Active Filters

Op Amp CircuitVin Vout

9

An is a circuit that has a specific shaped frequency response

A is made of op amps and has its own power supply. Advantages over RLC passive filters: Provides isolation (cascade filters) Boosts the power Can provide sharper roll-off

Summary

10

Lowpass filter

Next Lesson

11

Derivation: Vin = iZ1Vo = -iZf = -(Zf/Z1)Vin

Impedance Gain

inin

Fo VZ

ZV =

12

Slide Number 1Slide Number 2Previous LessonLesson ObjectivesAnalog FiltersQuizSummary of RC and RLC (Passive) FiltersLimitations of RLC Passive FiltersActive FiltersSummaryNext LessonImpedance Gain