SBOA503 July   2021 INA101 , INA103 , INA111 , INA114 , INA115 , INA118 , INA121 , INA122 , INA125 , INA126 , INA128 , INA128-HT , INA129 , INA129-EP , INA129-HT , INA141 , INA155 , INA156 , INA1620 , INA163 , INA1650 , INA166 , INA188 , INA2126 , INA2128 , INA2141 , INA217 , INA2321 , INA2331 , INA2332 , INA317 , INA321 , INA322 , INA326 , INA327 , INA330 , INA331 , INA332 , INA333 , INA333-HT , INA333-Q1 , INA337 , INA338 , INA818 , INA819 , INA821 , INA823 , INA826 , INA826S , INA827 , INA828 , INA848 , INA849

 

  1.   Trademarks
  2. 1Typical Instrumentation Amplifier Operation
  3. 2Problem Statement
  4. 3Common Mistake
  5. 4Proposed Solution
  6. 5Component Selection and Trade-Offs
  7. 6Common Applications
  8. 7Conclusion

7 Conclusion

Many applications that require low-level ac signal processing in the presence of large dc potentials require special additional circuitry. Simple mistakes while building the circuit can cause large errors and unexpected outputs. Providing a dc path to ground in dc or ac applications is a necessary step in circuit design. Properly designing these circuits requires an understanding of the sensor output impedance or the output impedance of the circuit driving the instrumentation amplifier, as well as the trade-offs in component selection.

See Table 7-1 for a list of some of TI’s high-precision low-Ib instrumentation amplifiers.

Table 7-1 Recommended High-Precision, Low-Ib Instrumentation Amplifiers From TI
Part Number Description
INA849 Ultra-low-noise (1 nV/√Hz), wide-bandwidth (28 MHz), high-precision (35 µV), super-beta, 36‑V IA with low input bias current (20 nA, maximum)
INA823 Low-power (250 µA), wide-supply (2.7 V to 36 V), precision, (150 µV), super-beta IA with low input bias current (15 nA), overvoltage protection, and below ground input voltage
INA821 Wide-bandwidth (4.7 MHz), low-noise (7 nV/√Hz), high-precision (35 µV), super-beta, 36‑V IA with low input bias current (0.5 nA, maximum) and overvoltage protection
INA819 Low-power (350 µA), low-noise (8 nV/√Hz), high-precision (35 µV), super-beta, 36‑V IA with low input bias current (0.5 nA, maximum) and overvoltage protection (alternative pinout available: INA818)
INA188 Zero-drift (0.2 µV/°C, 55 µV), low-noise (12 nV/√Hz), 36‑V, CMOS IA with low input bias current (2.5 nA, maximum)
INA333 Micro-power (50 µA), zero-drift (0.1 µV/°C, 25 µV), 5.5‑V CMOS IA with low input bias current (0.2 nA, maximum)
INA331

Very-low-bias-current (10 pA, maximum), low-power (0.01 µA with shutdown), low-current-noise (0.5 fA/√Hz), 5.5‑V CMOS IA
INA121 Very-low-bias (50 pA, maximum), low-current-noise (1 fA/√Hz), 36‑V, FET-input IA with overvoltage protection