EEL6935-F10-HLec03-opamps-2spp

# EEL6935-F10-HLec03-opamps-2spp - Lecture 3: Opamp Review...

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1 Lecture 3: Opamp Review Inverting amplifier Generalized impedances – Inverting integrator – Inverting differentiator Weighted summer Non-inverting amplifier Voltage buffer Non-linear amplifiers First, assume ideal op amp. Basic Opamp Op amp is a circuit that has two inputs and one output. It amplifies the difference between the two inputs.

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2 Inverting Amplifier Note: – Negative feedback – Find close loop gain Analysis Virtual short circuit: Due to infinite gain of op amp, the circuit forces V 2 to be close to V 1 , thus creating a virtual short. 1 2 0 R R V V i Closed loop gain Inverting Amplifier Note that the virtual ground is not actually shorted to ground; otherwise this would force all the current flowing through R2 to ground and Vout would be zero. The behavior of the virtual ground is similar to a seesaw, where the point between the two arms is pinned (does not move), allowing the displacement at point A to be “amplified” (and “inverted”) at point B.
3 Non-inverting amplifier A noninverting amplifier returns a fraction of output signal thru a resistor divider to the negative input. With a high Ao, Vout/Vin depends only on ratio of resistors, which is very precise. 2 1 2 1 2 1 R R R R R V V in out Closed loop gain Extreme Cases of R 2 (Infinite A 0 ) If R2 is zero, the loop is open and Vout /Vin is equal to the intrinsic gain of the op amp. If R2 is infinite, the circuit becomes a unity-gain amplifier and Vout /Vin becomes equal to one.

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4 Unity Gain Amplifier Why use this if Vout=Vin?
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## This note was uploaded on 01/17/2011 for the course ECE Biomedical taught by Professor Dr.rizwanbashirullah during the Fall '10 term at University of Florida.

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EEL6935-F10-HLec03-opamps-2spp - Lecture 3: Opamp Review...

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