2 What does an AMPLIFIER do? Integrated CircuitsWhat does an AMPLIFIER do?What is an IC?OP-Amp is an amplifier ICInside an IC
3 What can you do with Op amps? You can make music louder when they are used in stereo equipment.You can amplify the heartbeat by using them in medical cardiographs.You can use them as comparators in heating systems.You can use them for Math operations like summing, integration etc.
4 OP-AMP (operational amplifier) An OP-AMP is an integrated circuit (IC) used for amplification of signals.It is the most widely used analog IC.It is used in control systems, instrumentation, signal processing etc.The Operational Amplifier or "op-amp" is an amplifier with two inputs and one output. One input is the inverting input and the other is a non inverting input.
5 OP-AMP BLOCK DIAGRAM - V + V Output Differential Amplifier Figure 1 Op Amp Block DiagramInverting Input (- VIN)+ V- VOutputNoninverting Input (+ VIN)Differential AmplifierVoltage AmplifierOutput Amplifier
6 OP-AMP HAS 3 –STAGE AMPLIFIER CIRCUITS First Stage : Differential Amplifier -it gives the OP-AMP high input impedance (resistance)Second Stage: Voltage Amplifier – it gives high gainThird Stage : Output Amplifier (Emitter Follower) – gives low output impedance (resistance)
7 OP-AMP CHARACTERISTICS Very high input impedanceVery high gainVery low output impedanceOP-AMP is a differential, voltage amplifier with high gain.
8 OP-AMP is a differential, voltage amplifier with high gain. Why???? Differential Amplifier: Because it amplifies the difference between 2 voltagesVoltage Amplifier: Because input and output are voltagesHigh Gain Amplifier: Because the voltage gain is very high (> 100,000)
9 Figure : Op Amp packages The 741 Op-ampThe most common op-amp is the 741 IC.Packaging TypesFigure : Op Amp packages(b) OPA547FKTWTDIP SMT package(a) Op Amp 7418-pins DIP package(c) TO-5 metal can8-Leads package
11 Figure 4 Op Amp pins Description What are these pins?Figure 4 Op Amp pins Description123456781. Offset Null-VEE8. N / C6.Output7417. +VCC3. Noninverting Input +VIN2. Inverting Input –VIN5.Offset Null
12 What are these pins?Pin 1 and Pin 5 : Offset null input, are used to remove the Offset voltage.Pin 2: Inverting input (-VIN), signals at this pin will be inverted at output Pin 6.Pin 3: Non-inverting input (+VIN), signals at pin 3 will be processed without inversion.Pin 4: Negative power supply terminal (-VEE).Pin 6: Output (VOUT) of the Op-AmpPin 7: Positive power supply terminal (+VCC)Pin 8: No connection (N\C), it is just there to make it a standard 8-pin
13 Symbol of OP-AMP Figure 5 Op Amp Schematic Symbols +VS -VIN VOUT +VIN (a) Without power connection(b) With power connection
14 Most Op Amps require dual power supply with common ground Positive Supply (+15V) to pin7 Negative Supply (-15V) to pin4Figure 6 Dual Supply Voltages connection-VIN+-+VINVOUT+VS-VS74Common Ground
15 Some Op Amps work on single supply also Figure 7 Single Supply Voltages connection-VIN+-+VINVOUT-VS74+VS(a) Single Positive Voltage(b) Single Negative Voltage
16 Advantage of dual power supply Using dual power supply will let the op amp to output true AC voltage.0V+15V-15VOutputFigure 8a Op Amp powered from Dual supply+30VFigure 8b Op Amp powered from Single supply30 V
17 What is dual power supply? Single Power SupplyFigure 18 Dual Power SupplyCommon+15V–15V
18 How can you make a dual power supply using two 9V batteries? What is the voltage between + of first battery and – of second battery?
19 OP-AMP CONFIGURATIONS Figure Types of Feedback(a) No Feedback (open loop comparator circuit)(b) Negative Feedback(c) Positive Feedback
20 Feedback No feedback : Open loop (used in comparators) Negative feedback : Feedback to the inverting input (Used in amplifiers)Positive feedback : Feedback to the non inverting input (Used in oscillators(
21 (a) Comparator Circuit OP AMP as a Comparator (compares 2 voltages and produces a signal to indicate which is greater)+VSVO+VIN = –VIN–VS+VIN –VIN+VIN –VIN+VIN–VIN(a) Comparator Circuit(b) Comparator Output
22 Applications of Comparators Analog to digital converters (ADC)Counters (e.g. count pulses that exceed a certain voltage level).Cross Over Detectors
23 OP-AMPS WITH NEGATIVE FEEDBACK The two basic amplifier circuits with negative feedback are:The non-inverting Amplifier.The inverting Amplifier(Note: Negative feedback is used to limit the gain)
24 NON-INVERTING AMPLIFIER The input signal is applied to the non-inverting input (+VIN). The output is fed back to the inverting input through resistor RF.VOVINRFR1Figure 11 Closed-Loop Noninverting Amplifier CircuitWhere;VO = Output voltageVin= Input voltage= VfAin = Non inverting Gain
25 Problem:Calculate the gain of a non inverting amplifier if Rin=3K and Rf=30K. If Vin=4mV, calculate the output voltage.
26 INVERTING AMPLIFIERThe input signal is applied through a series input resistor RI to the inverting input. Also, the output is fed back through RF to the same input. The noninverting input is grounded.Where;VO = Output voltageVIN = Input voltageAI = Inverting GainVOVINRFRIN
27 Examples of Negative Feedback Applications: A) Inverting Amplifiers1.Summing Amplifier2.Differentiator3.IntegratorB) Non Inverting Amplifiers1. Voltage Follower
28 Figure 14 Summing Amplifier Summing Amplifier (Adder) : the inputs are added and the sum is inverted . If all resistors are of equal value, then Vo = -(V1 + V2+ V3)Figure 14 Summing AmplifierV1VOV2V30VR1R2R3RF
29 Differentiator (the input is differentiated with respect to time) Figure 16 Inverting Op-Amp as DifferentiatorCRVINVO
30 Integrator (the input is integrated with respect to time) Figure 15 Inverting Op-Amp as IntegratorRCVINVO
31 Voltage Follower (Non Inverting) It is a non inverting amplifier with gain=1So the output is the same as input.VINVOFigure 17 Voltage Follower
32 Positive Feedback is used in oscillators Astable Multivibrator (Relaxation Oscillator)VOR2R3R1C1Figure 13 A stable Multi-vibrator