Lecture16a

# Lecture16a - (V R =3V, -4V) – ? Schmitt Trigger Consider...

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Lecture 16. OP-AMP CIRCUITS Objectives: Topics: Perform analysis of op-amp circuits Describe operation of nonlinear op-amp circuits Sketch output signals Summation Amplifier Integrator and Differentiator Nonlinear Op-Amp Circuits

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Summation Amplifier - + V + =V - =0 v OUT = V - -R F i F Current through feedback resistor = summation of all input currents 1 1 1 1 1 R v R V v i IN IN = = ) ( 3 2 1 i i i R v F OUT + + =
Op-Amp Integrator v IN v OUT - + v OUT =V - -V C = i 1 =i C dt dv C C = EXAMPLE C=10 µ F, R=10k , v IN =4V, V pos =10V, V neg =-10V. Sketch v OUT v IN v OUT t t = = dt v OUT 4 10 * 10 * 10 * 10 1 6 3

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Op-Amp Differentiator v IN v OUT - + R C v IN v OUT R L - + v OUT = V - -Ri=-Ri v OUT = V - -V L =-V L
Nonlinear Op-Amp Circuits - operate outside the linear range No negative feedback – output saturates at V pos or V neg COMPARATOR/POLARITY INDICATOR + - v IN v OUT + - V R V R – reference voltage V R =0 – polarity indicator V R 0 - comparator v v t t 12 -12 12 -12 EXAMPLE v IN – 6V peak triangle wave, ± 12V power supply v OUT

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Unformatted text preview: (V R =3V, -4V) – ? Schmitt Trigger Consider a comparator circuit, when v IN ≈ V R (V +-V-≈ 0) Input noise could cause false triggering of the output v IN v OUT t t V R-+ v IN v OUT R 1 R 2 v IN v OUT Transfer characteristic The Schmitt trigger “remembers” its most recent positive or negative status- very susceptible to noise Schmitt Trigger (continued)-+ v IN v OUT R 1 R 2 V R v IN v OUT v IN =0 → v OUT = (V pos or V neg ) if v OUT = V pos : if v OUT = V neg : v IN v OUT t t V pos V neg EXAMPLE v IN – 6V peak triangle wave, ± 12V power supply 4 / 1 ) 2 1 1 = + R R R a 3 / 1 ) 2 1 1 = + R R R b Sketch v OUT v v t t 12-12 12-12 a) 2 thresholds: b) 2 thresholds: The Schmitt trigger is not sensitive to noise...
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## This note was uploaded on 06/30/2010 for the course EECE 315 taught by Professor Nikulin during the Fall '08 term at Binghamton.

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Lecture16a - (V R =3V, -4V) – ? Schmitt Trigger Consider...

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