1. 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

2. 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

3. 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

4. Compare the CMRR Performance Side by Side
Input Signal
(2V Scale)
Common Mode Error
at the Output
(1mV Scale)
AD623
G=5
INA 126
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

5. 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

6. 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

7. So Why Use The AD623 In Your Application?
ALP