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+. +. _. _. +. +. _. _. _. +. a. ALP. Why Use an instrumentation Amplifier?. Classic 3 Op-Amp architecture. 2 Op-Amp Architecture. To sense the difference between two signals, amplify it, and provide a single ended output. To keep errors low, it should:
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+ + _ _ + + _ _ _ + a ALP Why Use an instrumentation Amplifier? . Classic 3 Op-Amp architecture • 2 Op-Amp Architecture • To sense the difference between two signals, amplify it, and provide a • single ended output. • To keep errors low, it should: • Þ Reject common mode signals on its inputs • Þ Have low offset voltage • Þ Have low offset voltage drift • The in-amp should also be easy to use and easy to design into your system.
a ALP Why We Beat the Competition The AD623 uses the classic 3 op-amp architecture. The competition uses the two op-amp architecture. AD623 Architecture INA126 Architecture Why is this significant? The AD623 (3 Op-Amp Architecture) provides superior common mode rejection performance over the INA126 (2 Op-Amp Architecture). Look at the results of a simple side-by-side comparison.
a ALP The AD623 Keeps errors Constant AD623 Typical CMRR • From this graph you can see that: • The AD623 keeps CMV errors constant out to 200MHz. This architecture successfully rejects 60Hz line noise and its harmonics. • The common mode rejection performance of the BB INA126 drops off dramatically from 96 dB (typ) at 10 Hz to 72 dB (typ) at 200 Hz!
a ALP Compare the CMRR Performance Side by Side Input Signal (2V Scale) Common Mode Error at the Output (1mV Scale) INA 126 G=5 AD623 G=5 AD623 common mode error = 500mV INA 126 common mode error = 2mV The INA 126 gives you 4 times the error at a higher cost!
a ALP The Competition Gets Worse at Higher Gains! Same Input Signal (2V Scale) Common Mode Error at the Output (10mV Scale) AD623 G=100 INA 126 G=100 AD623 common mode error < 1mV INA 126 common mode error > 20mV The INA 126 gives you over 20x the error at a higher cost!
a ALP More Reason Why AD623 is Better Than BB INA126 Comparison of the AD623 and the INA126 in a typical application* * - 5V common mode signal - G=100 configuration - 20mV full scale signal - .02% resistor matching * The AD623 gives you lower cost and lower total error than you can get from Burr Brown! And it’s single supply with rail to rail output!
a ALP So Why Use The AD623 In Your Application?