To conduct a study on relaxation in long cables and accurately capture the trailing signal under rectangular pulse excitation, a TVS diode is employed to lower the amplitude of the relaxation signal. Nevertheless, the large junction capacitance values in conventional transient voltage suppressor (TVS) diodes pose significant challenges, including heightened insertion losses and distortions in the trailing signal’s waveform. To address these issues, we introduce a voltage limiter utilizing a TVS diode with reduced capacitance values. Fundamentally, its circuit is essentially a series and parallel circuit of diodes and TVS diode. The results indicate that this voltage limiter effectively protects the oscilloscope, mitigates signal integrity degradation, and significantly enhances the wave quality of the recorded trailing signal.