In this work, we investigate the frequency response of TiN/Ti/HfO2/W/Ti resistive switching devices (Fig. 1). The devices, featuring an active area of 1.44×10^(-2) mm2, consist of a 10 nm-thick HfO2 layer grown by ALD at 225ºC. Our study focuses on the temporal dynamics of oxygen vacancy-based filaments under variable-frequency stimuli. To overcome the limitations of standard equipment and carry out current-voltage (I-V) measurements at different frequencies, an ad-hoc experimental set-up was implemented, featuring a high-speed buffer and a transimpedance amplifier (current-to-voltage converter) connected to a digital oscilloscope (Fig. 2a). The reliability of this circuit was validated by comparing low-frequency I-V curves with those obtained using a Keysight B2912B SMU, showing excellent agreement (Fig. 2b). Electrical characterization reveals that the input signal frequency critically influences the resistive switching (RS) stability. As the frequency increases, oxygen ions fail to follow the electric field variations due to time constraints, leading to a reduction in the resistance window (Fig. 3), which is consistent with the simulation results of Dongale et al. [1]. Interestingly, we observed that both set and reset voltages exhibit a linear dependence with the logarithm of the frequency (Fig. 4). These results are consistent with our previous findings obtained using different voltage ramp rates (VRRs) [2], where switching thresholds were shown to increase with the VRR. At the highest frequencies, the ions' response is so limited that the filamentary transitions vanish, resulting in the collapse of the memory window. These findings suggest that frequency can be used as a primary control parameter to modulate synaptic weights in neuromorphic applications, where precise control of intermediate conductance states is required [3].