1. AD8604ARZ Substitution Conclusion Direct substitution is not viable for applications with stringent compatibility requirements on key parameters, particularly supply voltage and input offset voltage. The primary differences are as follows: First, its supply voltage range (2.7V to 5.5V) is incompatible with the original part's minimum startup voltage of 1.8V, rendering it non-functional in systems operating between 1.8V and 2.7V. Second, while its ultra-low input bias current (0.2 pA vs. 16 nA) and input offset voltage (80 µV vs. 1 mV) represent significant advantages—offering superior performance in applications such as high-impedance sensor signal conditioning and precision measurement—they may render the original design's input bias current compensation circuit redundant or even detrimental. Furthermore, the higher gain bandwidth product (8.4 MHz vs. 630 kHz) and slew rate (6V/µs vs. 0.25V/µs) could lead to circuit oscillation or increased noise if stability and noise performance are not re-evaluated. This substitute is only suitable for a redesign targeting supply voltages ≥2.7V and demanding ultimate precision and speed.