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CHAPTER 8. IDEAL OPERATIONAL AMPLIFIER AND OP-AMP CIRCUITS. Op-amp circuit symbol. Open loop mode V o = A od ( V 2 – V 1 ) A od is referred to as the open loop gain. Notice that is V 2 = V 1 , the open loop gain equals to . inverting. output. non-inverting.
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CHAPTER 8 IDEAL OPERATIONAL AMPLIFIER AND OP-AMP CIRCUITS
Op-amp circuit symbol • Open loop mode • Vo = Aod ( V2 – V1) • Aod is referred to as the open loop gain. • Notice that is V2 = V1, the open loop gain equals to inverting output non-inverting
Final Exam SEM II 2012/2013 An ideal op-amp, was measured in a lab experiment in open-loop mode. Determine the open loop gain (Aod) and complete the table below which shows the results of the experiment. -0.506 V 0.99 V
Op amp can be configured to be used for different type of circuit applications: • Inverting Amplifier • Non – inverting Amplifier • Summing Amplifier • Integrator • Differentiator
Inverting Amplifier Op-amp as an inverting amplifier Voltage at node 1 (inverting) = voltage at node 2 (non-inverting ) KCL at node 1: (Vi – 0) / R1 = (0– Vo) / R2 Vi / R1 = - Vo / R2 Vo = - R2 Vi R1
Exercise 8.3 Gain = - (R2 / R1) = -(150/12) = -12.5
Can the voltage gain be calculated the using the same formula? Try and use the same method in deriving Vo/Vi
Non - Inverting Amplifier Voltage at node 1 (inverting) = voltage at node 2 (non-inverting ) KCL at node 1: (0– Vi) / R1 = (Vi – Vo) / R2 -(Vi / R1) = (Vi / R2) – (Vo / R2) Vo / R2 = (Vi / R2) + (Vi / R1) = Vi 1 + 1 Vo / Vi = R2 1 + 1 R2 R1 Noninverting amplifier R2 R1
Voltage Follower / Buffer Amplifier Vo = Vi Hence, gain = 1
Summing Amplifier Similarly, i1 + i2 + i3 – i4 – 0 = 0
Integrator Integrator circuit
Differentiator EXAMPLE 8.4 Differentiator circuit
Calculating Gain and Design Questions NON - INVERTING INVERTING Calculating Output and Design Questions SUMMING AMPLIFIER INTEGRATOR AMPLIFIER DIFFERENTIATOR AMPLIFIER
Calculate the input voltage if the final output, VO is 10.08 V.
Answering the questions • Please write down the questions you attempted on the cover page • Organize your thoughts. When it is organized, so will your workflow. • Messy work will make the lecturers feel annoyed as they have to look for your answers– bear in mind that lecturer handling one section = 50-60 students – each paper has 5 questions • TOTAL – 250 to 300 questions to mark • Don’t leave a question blank – just write down anything you know that might be related • Be tactical. • Study smart, pray and tawakal.