SMD resistors and off-the-shelf current viewing resistors (CVRs) can introduce parasitic inductance that causes ringing and exaggerated peaks. This paper describes a technique for defining a simple RC filter to enable shunt-based current measurements beyond 1 MHz.
VNA measurements are used to determine the frequency response of a physical shunt. Time domain measurements show the impact of the parasitic inductance.
The shunt is then modeled as a series RL circuit and an RC filter is added to the simulation to flatten the response. The RC filter is applied and measured to show improvements in both the frequency domain (VNA) and time domain (oscilloscope).