8/12/2019 Analog_lect_9_02022012

http://slidepdf.com/reader/full/analoglect902022012 1/22

EEE C364/INSTR C 364

Analog Electronics

Lecture 9

02-02-2012

8/12/2019 Analog_lect_9_02022012

http://slidepdf.com/reader/full/analoglect902022012 2/22

Schmitt Triggers

8/12/2019 Analog_lect_9_02022012

http://slidepdf.com/reader/full/analoglect902022012 3/22

Schmitt Trigger Circuits

 sat UT 

  V  R R

 RV   

21

1

 sat  LT    V  R R

 R

V    21

1

 sat  sat  LT UT  H 

  V V  R R

 RV V V   

21

1

8/12/2019 Analog_lect_9_02022012

http://slidepdf.com/reader/full/analoglect902022012 4/22

Schmitt Trigger Circuits

8/12/2019 Analog_lect_9_02022012

http://slidepdf.com/reader/full/analoglect902022012 5/22

Schmitt Trigger Circuits

 

 

 

21

1

21

1

21

1

21

112

21

1

21

2

21

1

 

 R R

 RV V V 

V V  R R

 RV 

 R R

 R

V  R R

 R R RV  R R

 R

V  R R

 RV 

 R R

 RV 

ref  sat ref 

ref ref  sat 

ref  sat 

ref  sa t UT 

21

12 R R

V  RV V V 

  sat 

 LT UT  H 

 

   

21

1

21

1

21

1

21

112

21

1

21

2

21

1

  R R

 RV V V 

V V  R R

 RV 

 R R

 R

V  R R

 R R RV 

 R R

 R

V  R R

 RV 

 R R

 RV 

ref  sat ref 

ref ref  sat 

ref  sat 

ref  sat UT 

8/12/2019 Analog_lect_9_02022012

http://slidepdf.com/reader/full/analoglect902022012 6/22

Difference Amplifier 

8/12/2019 Analog_lect_9_02022012

http://slidepdf.com/reader/full/analoglect902022012 7/22

Difference Amplifier with input Buffering

Voltage follower 

8/12/2019 Analog_lect_9_02022012

http://slidepdf.com/reader/full/analoglect902022012 8/22

Variable gain Instrumentation Amplifier 

8/12/2019 Analog_lect_9_02022012

http://slidepdf.com/reader/full/analoglect902022012 9/22

Variable gain Instrumentation Amplifier 

+3 V

+3 V

+3 V

+3 V

+3 V

+3 V

I=0

I=0

8/12/2019 Analog_lect_9_02022012

http://slidepdf.com/reader/full/analoglect902022012 10/22

Variable gain Instrumentation Amplifier 

+3 V

+1 V+1 V

+3 V

I=2/R1I=2/R1

12

1

2'

1

'

2

1

2

1

12

'

1

'

2

12

212

 

22

V V  R

 RV V 

 R

 R

 R R RV V 

 

  

 

 

  

 

8/12/2019 Analog_lect_9_02022012

http://slidepdf.com/reader/full/analoglect902022012 11/22

 An Instrumentation Amplifier 

'2'

1

1

0   V V  R

 RV   F 

21

11

20 V-V

21 Therefore

 R

 R

 R

 RV 

  F 

 

 

 

 

12

1

2'

1

'

2 12V V 

 R

 RV V   

  

  

8/12/2019 Analog_lect_9_02022012

http://slidepdf.com/reader/full/analoglect902022012 12/22

Symbol of Instrumentation Amplifier 

)(2

1 210   V V a

V     

  

  21

11

20 V-V

21

 R

 R

 R

 RV 

  F 

 

  

 

Where all resistors are of value R

and R1= aR

8/12/2019 Analog_lect_9_02022012

http://slidepdf.com/reader/full/analoglect902022012 13/22

Isolation Amplifier 

 Applications: Bio-Medical Instrumentation

Industrial control

8/12/2019 Analog_lect_9_02022012

http://slidepdf.com/reader/full/analoglect902022012 14/22

Isolation Devices

 An isolation Device passes a signal, either analog or digital, from

input to output across an isolation barrier.

 An isolation barrier ensures that there is no galvanic or ohmic

connection between input and output

Isolation barrier must have high breakdown voltage

Low dc leakage current (HIGH BARRIER RESISTANCE)

Low ac leakage current (LOW BARRIER CAPACITANCE)

8/12/2019 Analog_lect_9_02022012

http://slidepdf.com/reader/full/analoglect902022012 15/22

Isolation Devices: Basic concepts

Where VISO: Isolation-mode voltage

IMRR: Isolation-mode rejection ratio

GAIN  IMRR

V 

CMRR

V V V 

  ISOCM 

SIGO 

 

 

 

 

Fig 3.6 Equivalence of isolation barrier 

8/12/2019 Analog_lect_9_02022012

http://slidepdf.com/reader/full/analoglect902022012 16/22

The Topics covered in this session

Isolation Amplifier 

Isolation device technology

Programmable Gain Amplifier 

Negative feedback amplifiers and controlled sources

Voltage controlled Voltage source or Voltage series feedback amplifier 

Instrumentation amplifier 

8/12/2019 Analog_lect_9_02022012

http://slidepdf.com/reader/full/analoglect902022012 17/22

Isolation Device Technology

Transformer isolation

Optical Isolation

Capacitor isolation

8/12/2019 Analog_lect_9_02022012

http://slidepdf.com/reader/full/analoglect902022012 18/22

Isolation Device Technologycontd..

8/12/2019 Analog_lect_9_02022012

http://slidepdf.com/reader/full/analoglect902022012 19/22

Isolation Device Technology contd..

8/12/2019 Analog_lect_9_02022012

http://slidepdf.com/reader/full/analoglect902022012 20/22

Isolation Device Technology contd..

8/12/2019 Analog_lect_9_02022012

http://slidepdf.com/reader/full/analoglect902022012 21/22

Isolation Device Technology contd…

Optical isolator or opto isolator or opto coupler or photo coupler or photo MOS

8/12/2019 Analog_lect_9_02022012

http://slidepdf.com/reader/full/analoglect902022012 22/22

Optical isolator or opto isolator or opto coupler or photo coupler or photo MOS