Outline

• Review

1/21/2015

• Summary

• Single time Constant (STC) Networks

• Frequency Response of Amplifiers

Outline

1

Single time Constant (STC) Networks

Frequency Response of Amplifiers

Review

1/21/2015

• Voltage Amplifier

• STC Networks

• Frequency Response of Amplifiers

Review

2

Frequency Response of Amplifiers

STC Networks

• This passes low frequency sine wave inputs with little or no attenuation at w= 0

• Attenuates the high frequency input sinusoids

• This is a Low pass Filter

1/21/2015

STC Networks

This passes low frequency sine wave inputs with little or no attenuation at w= 0

Attenuates the high frequency input sinusoids

a Low pass Filter3

Consider the circuit below.

R

CVI

+

_

1( )

1( ) 1OV jw jwC

V jw jwRCRi jwC

Low pass filter circuit

Low Pass FilterConsider the circuit below.

C VO

+

_

1( ) 1V jw jwRC

Low pass filter circuit

Low Pass Filter

1( )

1( ) 1OV jw jwC

V jw jwRCRi jwC

Low Pass Passive Filter

jωSubstituting

1( ) 1V jw jwRC

Low Pass Passive Filter

ω = s

Low Pass Passive Filter

ωSubstituting

ω0 = Corner Frequency

Low Pass Passive Filter

ω0 = 1 / RC

= Corner Frequency

Example-

Input

-Low Pass

Output

1/21/2015

Design Low pass Filtercutoff frequency 150Hz

Filter for sub woofer withHz

Consider the circuit below.

C

RVi

+

_

( )1( ) 1

OV jw jwRCRV jw jwRCRi jwC

High Pass Filter

High Pass Passive Filter

Consider the circuit below.

VO

+

_

1( ) 1V jw jwRCRV jw jwRC

jwC

High Pass Filter

High Pass Passive Filter

( )1( ) 1

OV jw jwRCRV jw jwRCRi jwC

High Pass Passive Filter

jωSubstituting

( ) 1V jw jwRCV jw jwRC

High Pass Passive Filter

ω = s

High Pass Passive Filter

ωSubstituting

ω0 = Corner Frequency

High Pass Passive Filter

ω0 = 1 / RC

= Corner Frequency

Example-High Pass

Input

High Pass

Output

Revisit :Frequency Response of Amplifiers

• A linear amplifier fed at its input with a sinewave signal Vi and frequency

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Revisit :Frequency Response of Amplifiers

A linear amplifier fed at its input with a sine-and frequency ω

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Frequency Response Low Pass Filter

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Frequency Response Low Pass Filter

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Frequency Response Low Pass Filter

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Frequency Response Low Pass Filter

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Active Filter

Active Element

BJTAmplifier

MOS Amplifier 16

Active Filter

Active Element

MOS Amplifier

OPAMP Amplifier

Frequency response of STC networks

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Frequency response of STC networks

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Frequency response of STC networks

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Frequency response of STC networks

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