SLYT840 june   2023 INA333 , INA350

 

  1.   1
  2. 1Introduction
  3. 2Dual-supply circuits
  4. 3PCB layout
  5. 4Measurement results
  6. 5Conclusion

4 Measurement results

Gain and offset errors were used as a measure of the relative performance of each circuit across temperature. As a baseline measurement, the precision dual-supply IA was put in a gain of 1 V/V (RG = open). For each sweep, the input signals were scaled such that the output voltage ranged from –2 V to +2 V.

Table 1 depicts the baseline gain and offset errors for the precision IA, G = 1 V/V across temperature. The table includes the data sheet’s typical gain and offset error values at 25°C, to validate the measurement system.

Table 1 Precision IA gain and offset error vs. temperature (G = 1 V/V).
Temperature –40°C 0°C 25°C 100°C 125°C
Error Type Gain Offset Gain Offset Gain Offset Gain Offset Gain Offset
Measured (data sheet typical) 0.00270% 10.1 µV 0.00019% 9.1 µV –0.00281%
(±0.01%)		 7.5 µV
(±35 µV)		 –0.00523% 23.5 µV –0.00572% 31.2 µV

Table 2 depicts the gain and offset error (referred-to-output [RTO]) for all IAs in a gain of 10 V/V and across temperature. The green shading indicates the highest-performing implementation at each temperature.

Table 2 Gain and offset error (RTO) vs. temperature (Gain = 10 V/V).
Temperature –40°C 0°C 25°C 100°C 125°C
Error Type Gain Offset Gain Offset Gain Offset Gain Offset Gain Offset
Discrete IA –0.60853% –4.09 mV –0.70079% –3.67 mV –0.73929% –4.07 mV –0.90846% –4.07 mV –0.95486% –3.69 mV
General-purpose IA –0.02532% 2.07 mV –0.03182% 2.05 mV –0.00250% 2.04 mV 0.00876% 2.12 mV –0.00970% 2.21 mV
Precision IA 0.17320% –58.8 µV 0.08103% –43.2 µV 0.02941% –35.2 µV –0.06125% –2.2 µV –0.07883% 33.8 µV

From a performance perspective, Table 1 and Table 2 show that without an external RG, the precision dual-supply IA is superior to all other solutions. From a gain error perspective, the general-purpose and precision IA solutions are comparable. This is primarily because of the external RG required for the G = 10 V/V precision IA implementation, whereas the general-purpose solution integrates RG. When looking at the offset error, the precision IA solution is clearly the most accurate, while the general-purpose offset error is about half that of the discrete solution. Overall, the discrete IA has significantly worse performance when compared to both integrated solutions.