Mahatma Phule Arts Science And Commerce College Panvel

Mahatma Phule Arts, Science And Commerce College, Panvel ( Academic Year 2015 – 2016 ) SEMESTER SECOND F. Y. B. Sc. Topic: Operational Amplifiers 09/01/2015 13/01/2015 By Dr. Sarode M. T. Department of Physics

Introduction ØThe operational amplifier or op-amp is a circuit of components integrated into one chip. ØA typical op-amp is powered by two dc voltages and has an inverting(-) and a non-inverting input (+) and an output. ØAn op amp is an electronic device which provides a voltage output based on the voltage input 09/01/2015 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 2

Basic op-amp Op-amp has two inputs that connect to two terminals and one output 09/01/2015 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 3

Operational Amplifiers Five important pins l l l 09/01/2015 2 3 6 4 7 – – – The The The inverting input non-inverting input output negative power supply V- (-Vcc) positive power supply V+ (+Vcc) Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 4

Operational Amplifiers ¡ The output of the op amp is given by the following equation: and ¡ Vd = E 1 – E 2 Vo = AVOL(Vd) AVOL is called the open-loop voltage gain because it is the gain of the op amp without any external feedback from output to input Dr. M. T. Sarode Dept. Of Physics, 09/01/2015 M. P. A. S. C>College, Panvel 5

Operational Amplifiers 09/01/2015 Positive Saturation – where the output voltage exceeds the positive power input Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 6

Operational Amplifiers 09/01/2015 Linear Region – where the output voltage is linear based on A (gain) Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 7

Operational Amplifiers 09/01/2015 Negative Saturation – where the output voltage would be less than the negative power input Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 8

Operational Amplifiers 09/01/2015 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 9

What do they really look like? 09/01/2015 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 10

IC Circuit 09/01/2015 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 11

Operational Amplifiers 09/01/2015 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 12

Operational Amplifiers ØAn ideal op-amp has infinite gain and bandwidth, we know this is impossible. ØHowever, op-amps do have: Øvery high gain Øvery high input impedance(Zin = ∞) Øvery low output impedance (Zout = 0) Øwide bandwidth. 09/01/2015 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 13

Application in op-amp ¡ ¡ 09/01/2015 There are 2 types of application in op-amp l Linear application l Non-linear application Linear application is where the op-amp operate in linear region: l Assumptions in linear application: ¡ Input current, Ii = 0 ¡ Input voltage: V+=V¡ Feedback at the inverting input Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 14

Application in op-amp ¡ ¡ ¡ 09/01/2015 Non-linear application is where the op-amp operate in non-linear region By comparing these two input voltages: positive input voltages, V+ and negative input voltage, V - where: VO = VCC if V+ > VVO = -VEE if V+ < VInput current, Ii = 0 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 15

Applications of op-amp l l l 09/01/2015 Comparator (Pembanding) Inverter (Penukar) Audio amplifier (Penguat Audio) Difference Amplifier (Penguat Beza) Filter (Penapis) Summing Amplifier (Penguat Jumlahan) Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 16

Op-amp Circuit Application l l l l 09/01/2015 Penguat menyongsang Penguat tidak menyongsang Penambah menyongsang Pengikut voltan Penguat penolak Penguat instrumentasi Pengamil Pengkerbezaan Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 17

Op-amp Circuit Application ¡ ¡ ¡ ¡ 09/01/2015 Inverting Amplifier Non-Inverting Amplifier Summing Amplifier Unity Follower Difference Amplifier Integrators Differentiators Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 18

Application: Inverting amplifier ¡ ¡ ¡ Provide a constant gain multiplier Input signal is connected to the inverting input of the opamp. Therefore, the output signal is 180 degree out of phase from the input signal Rf is the feed-back Dr. resistor to control the voltage gain of M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 19 the op-amp 09/01/2015

Summary of op-amp behavior Vo = A(V+ - V ) Vo/A = V+ - V Let A infinity then, V+ - V 09/01/2015 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 0 20

Summary of op-amp behavior V+ = V I+ = I = 0 Seems strange, but the input terminals to an op-amp act as a short and open at the same time 09/01/2015 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 21

To analyze an op-amp circuit for linear operation • Write node equations at + and - terminals (Ii=I+ = I- = 0) • Set V+ = V • Solve for Vo 09/01/2015 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 22

Analysis of inverting amplifier If I 1 09/01/2015 Ii Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 23

Application: Non-inverting amplifier 09/01/2015 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 24

Non-inverting configuration I 2 I 1 Ii Vi 09/01/2015 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C College, Panvel 25

Application: Summing amplifier Virtual-ground equivalent circuit. 09/01/2015 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 26

Summing Amplifier Rf V 1 V 2 R 1 R 2 R 3 V 3 This circuit is called a weighted summer 09/01/2015 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 27

Application: Unity Follower(Pengikut Voltan) 09/01/2015 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 28

Application: Difference amplifier (Penguat Penolak) 09/01/2015 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 29

Application: Instrumentation Amplifier (Penguat Instrumentasi) Buffer (Penimbal) Difference amplifier 09/01/2015 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 30

Application: Integrator (Pengamil) I IC Feedback component = capacitor : Integrator 09/01/2015 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 31

Application: Differentiation (Pengkerbezaan) 09/01/2015 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 32

Exercise 1 Find VO? 09/01/2015 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 33

Exercise 2 Find V 2 and V 3? 09/01/2015 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 34

Exercise 3 Find VO? 09/01/2015 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 35

Exercise 4 Find VO? 09/01/2015 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 36

Recall: Non-linear application in op-amp ¡ ¡ ¡ 09/01/2015 Non-linear application is where the op-amp operate in non-linear region By comparing these two input voltages: positive input voltages, V+ and negative input voltage, V - where: VO = VCC if V+ > VVO = -VCC if V+ < VInput current, Ii = 0 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 37

Non-linear application: Comparator (Pembanding) 09/01/2015 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 38

Non-linear application: Comparator (Pembanding) (a) Input Voltage of Comparator VS(V) t Compare V+ and VV+=0 V-=VS When: VS>0, V+>VVS<0, V+<V 09/01/2015 Vo(V) 10 t so Vo=10 V so Vo=-5 V -5 (b) Output Voltage of Comparator Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 39

Non-linear application Schmitt Trigger (Pemicu Schmitt) Positive Feedback - + 09/01/2015 Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 40

Non-linear application Schmitt Trigger (Pemicu Schmitt) VS(V) (b) Input Voltage of Schmitt Trigger 7. 5 t -7. 5 (a) Transfer Characteristic of Schmitt Trigger Vo(V) 15 15 -10 -7. 5 -15 09/01/2015 10 VS(V) t -15 (c) Output Voltage of Schmitt Trigger Dr. M. T. Sarode Dept. Of Physics, M. P. A. S. C>College, Panvel 41