Presentation is loading. Please wait.

Presentation is loading. Please wait.

Operational Amplifier

Similar presentations

Presentation on theme: "Operational Amplifier"— Presentation transcript:

1 Operational Amplifier

2 Ideal OP Amp Circuit model Two golden rules to perform calculations on op amps with negative feedback: iin=0, no current flow into op amp. V+=V- Typically one end of op amp is connected to ground, therefore, V+=V-= 0V, virtual ground. Often V+ is connected to ground to avoid stability problem.

3 Applications: building block for analog systems
Amplifiers Adders and Substractors Integrators & Differentiators Clock generators Filters Digital-to-analog converters

4 Using op-amps No flexibility

5 Let’s build a circuit……noninverting amplifier

6 When A is very large Suppose A=106, R1=9R, R2=R Gain:
determined by resistance ratio insensitive to A, temperature, fab variation

7 Why did this happen? Negative feedback
e.g. vIN=5V Suppose I perturb the circuit (e.g. force v0 momentarily to 12V somehow Stable point is when v+v- Key: negative feedback  portion of output fed to –ve input. e.g. Car antilock brakes  small corrections

8 How to control a high-strung device
Antilock brakes

9 More op amp insights: Observe, under negative feedback, We also know
 Yield an easier analysis method (under negative feedback)

10 Insightful analysis method: under negative feedback

11 Voltage follower Why is this circuit useful?
has minimum effects on previous and next circuit.

12 Inverting Amplifier Feedback resistor, always to negative input

13 Summing Amplifier: Add Circuit

14 Non-innverting Amplifier
Feedback resistor, always to negative input

15 Differential Amplifier: Substractor
Very useful if both signals are corrupted with noise: Electrocardiogram (EKG)

Download ppt "Operational Amplifier"

Similar presentations

Ads by Google