Instrumentation Amplifiers-Mesaurement and Instrumentation-Lab Mannual, Exercises of Electronic Measurement and Instrumentation

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EE 416 Fundamentals of Biomedical Engineering Laboratory INSTRUMENTATION AMPLIFIERS | LINTRODUCTION Objectives : To observe the common mode rejection performance of instrumentation amplifier circuits using different operational amplifiers at different frequencies and to understand the concept of interference, isolation and performing different measurement techniques to see how the measurement technique effects common mode interference, Equipment: Osciloscope Signal Generator Digital Multimeter Breadboard Average Time to Complete : 3 hrs Prerequisites : knowledge on op-amps, common mode rejection ratio, amplifiers, I. BACKGROUND INFORMATION Common Mode Rejection Ratio Almost all biopotential signals are in the form of difference signals: with small amplitudes superimposed on large common mode signals, Also many transducers used in biomedical applications generate such difference signals. This is why we use difference amplifiers in biomedical instrumentation. For biopotential amplifiers, line interference is the most important problem. Since the interference in biopotential. signals is in the form of a common signal, common mode rejection performance of an instrumentation amplifier is very important. Common Mode Rejection Ration (CMRR) of an amplifier is defined as Differential Mode Gain (A,,,) CMR = 2010 Common Mode Gain (Ae,) (@) g As it is seen from the above definition either common mode gain is minimized or differential gain is maximized to maximize CMRR. But since the operational amplifier characteristic depend on frequency, the CMRR performance of the amplifier also depends on the frequency, Interference Electric power systems is the major source of artifact, and it causes interference at line frequency. There are four ways in which an electromagnetic source such as 50 Hz power lines can cause interference in biopotential signals, docsity.com