1. AD621ARZ-RL Substitution Conclusion The AD621ARZ-RL, being an instrumentation amplifier of the same type, can be directly substituted for the INA141UA/2K5 in terms of package and supply voltage range. However, its key dynamic performance specifications are notably inferior, which may compromise signal fidelity in a direct replacement. The differences are as follows: The AD621 offers lower bandwidth (800 kHz vs. 1 MHz) and slew rate (1.2 V/µs vs. 4 V/µs) compared to the original part, resulting in reduced amplification capability for high-frequency signals and slower response to fast-changing signals (i.e., poorer transient performance). In applications where the original design operates at high frequencies or with rapid transients, this may lead to output signal distortion or response lag. Its input offset voltage is higher (75 µV vs. 20 µV), which can degrade DC accuracy and increase zero-error. On the other hand, the AD621 exhibits lower input bias current (500 pA vs. 2 nA), which is advantageous when interfacing with high-impedance signal sources to minimize current-induced errors.