ME 140L - Lecture 4 - Op Amps

# ME 140L - Lecture 4 - Op Amps - MECHATRONICS LAB ME 140L...

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1 MECHATRONICS LAB ME 140L OPERATIONAL AMPLIFIERS— CHARACTERIZATION AND OP-AMP CIRCUITS CONSIDER THE FOLLOWING You are asked to control pressure in a combustion chamber by manipulating the position of an air regulator valve connected to a high pressure source. Someone has selected a pressure transducer that has the correct pressure range, frequency response, reliability, etc. You can expect to see a minimum pressure of 100psia and a maximum of 500psia. For that range of pressures, the output of the pressure sensor is between 0.5V (at 100psia) and 1.3 V (at 500psia). The pressure sensor is to be interfaced with the analog input of the computer’s 16-bit analog-to-digital data acquisition card which accepts voltages from 0 to 5 volts. Design an interfacing circuit with the best resolution possible to bring the pressure reading to the computer. Sensor Output, V DAC Input, V

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I. OP-AMP CHARACTERISTICS Fundamental open-loop characteristics (no feedback from output to input) 1. Differential gain (realistically 2x10 4 -10 6 ) 2. Input resistance (realistically 2M Ω ) implies op-amp draws no current 3. Output resistance 0 4. Bandwidth implies fast and responses to wide frequency range 5. Offset and drift 0 v_ v+ +Vcc -Vcc Vo Vo = A ( V+ - V_) - inverting input + noninverting input Since A is very large ( ) and v o is finite, so approximate
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## This note was uploaded on 09/18/2011 for the course ME 140L taught by Professor Staff during the Fall '09 term at University of Texas at Austin.

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ME 140L - Lecture 4 - Op Amps - MECHATRONICS LAB ME 140L...

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