A floating inverter amplifier (FIA) is an alternative amplifier for switched-capacitor circuits. FIA-based switched-capacitor circuits have both negative feedback and dynamic operation advantages. However, the self-cutoff operation creates time-varying operating points while acting as an amplifier. Therefore, a small-signal analysis cannot anticipate the system's response. This paper presents a circuit-design-oriented intuition to tame the step response of such circuits. Also, the simulation method using RF simulators is explained to verify the gain and noise performance. Finally, a Miller-compensated 2-stage FIA is designed based on described design procedure, then applied to a fully dynamic zoom ADC design. The prototype ADC achieves 101.6 dB signal-to-noise and distortion ratio (SNDR) with an SNDR-based Schreier figure of merit (FoM) of 174.2 dB at 2.56-MHz fs having linearly scalable bandwidth and power consumption as fs varies, as well as easy power duty-cycling.