1. AD621BRZ-RL Substitution Conclusion Direct substitution of the AD621BRZ-RL for the original INA118 is not straightforward and requires careful evaluation. Key differences are as follows: Its input offset voltage (50 µV) is 5 times higher than that of the INA118 (10 µV). This will likely introduce greater initial error and temperature drift when amplifying weak DC or low-frequency signals, compromising measurement accuracy. Its supply current (900 µA) is over 2.5 times the INA118's (350 µA), significantly increasing system power consumption and making it unsuitable for battery-powered applications. Its minimum operating voltage (4.6 V) is substantially higher than the INA118's 2.7 V, rendering it incompatible with designs requiring single-supply or low-voltage (e.g., 3.3V system) operation. While it offers lower input bias current (500 pA), higher output current (18 mA), and a higher slew rate (1.2 V/µs), these advantages generally do not offset the significant compromises in critical parameters: precision, power consumption, and voltage compatibility.