Opamp Appication Essay

2563 Words 11 Pages
EMT 212/4
Chapter 2 – Op-amp Application



Op-amp Application
 Introduction
 Inverting Amplifier
 Non-inverting Amplifier
 Voltage Follower / Buffer Amplifier
 Summing Amplifier
 Differencing Amplifier
 Integrator
 Differentiator
 Comparator
 Summary
Frequency Response

Op-amp Application

Op-amps are used in many different applications. We will discuss the operation of the fundamental op-amp applications. Keep in mind that the basic operation and characteristics of the op-amps do not change — the only thing that changes is how we use them

Inverting Amplifier

Circuit consists of an op-amp and three resistors
The positive (+)
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The negative (-) input to the op-amp is grounded through R1 and also to the feedback signal from the output (via RF).
The positive (+) input is connected to the input signal Non-Inverting Amplifier
Input current to op-amp is very small. No signal voltage is created across
R2 and hence V   vin
V   V so it follows that;

 V   vin

Non-Inverting Amplifier so RF and R1 carry the same current. Hence vout is related to V through a voltage-divider relationship  I  0

V  vout R1  RF

R1 vin  vout R1  RF

Av 
 1 vin R1

Non-Inverting Amplifier

The output has the same polarity as the input

a positive input signal produces a positive output signal.

The ratio of R1 and RF determines the gain.

When a voltage is applied to the amplifier, the output voltage increases rapidly and will continue to rise until the voltage across R1 reaches the input voltage. Thus negligible input current will flow into the amplifier, and the gain depends only on R1 and RF

Non-Inverting Amplifier

The input resistance to the non-inverting amplifier is very high because the input current to the amplifier is also the input current to the op-amp, I+, which must be extremely small Non-Inverting Amplifier

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