Question

What are the main differences between AD 620 and LM 741. Why is the AD 620 used in the Amplification module and the LM 741 used in the filtering module of the EMG and ECG circuits.

Answer 1

AD620 is a Instrumentation Amplifier which has higher gain between 1-10000, high CMRR around 100db, requires less power. While LM471 is operational Amplifier, which a Differential input amplifier. AD 620 is an instrumentation amplifier which far better than three opamp instrumentation amplifier. Operational Amplifier is used to filter signal.

AD620 instrumentation amplifier is basically design for amplification of ECG and EMG as it has high gain, high common mode rejection ratio, low input bias current, low power. In medical application accuracy is very important hence ad620 is better than lm471. Ad620 has 9nV/?Hz, which is best for amplification. LM 741 operational amplifier is used as a amplification purpose but if we are using it for medical application then it is suitable to use it as filter, because it has high common mode rejection ratio which eliminates noise present in signal. It takes differerential input signal to produce accurate signal. but as AD620 is better in performance and as it is made for medical application it is used for amplification purpose.