1. AD648JRZ-REEL7 Substitution Conclusion Direct substitution is not recommended. While both are dual op-amps with the same maximum supply voltage, their core performance specifications and intended applications are fundamentally different. The AD648, being a J-FET input op-amp, offers the key advantage of extremely low input bias current (5 pA vs. 50 nA), making it suitable for applications like high-impedance sensor signal acquisition that require microampere-level quiescent current. However, its bandwidth (1 MHz) and slew rate (1.8 V/µs) are significantly lower than those of the original part (14 MHz, 7 V/µs), severely limiting its performance in high-speed signal processing or applications requiring fast settling. The most critical limitation is its minimum operating voltage of 9V, whereas the original part can operate down to 2.5V. This renders the AD648 completely unsuitable for any single-supply or low-voltage (e.g., 3.3V or 5V) system. Substitution may only be considered if the application is strictly confined to a higher supply voltage, has no speed requirements, but demands stringent input current specifications. Otherwise, it is not a viable direct replacement.