@Felthry Wait what? *blinks, earfocuses*
@IceWolf Almost all high-bandwidth current sensors are based around passing the current to be sensed through an extremely precise resistor of the lowest resistance possible (to not disturb the circuit too much) and measuring the voltage across that with a high-bandwidth amplifier and ADC. Magnetic current sensors like current transformers and Hall-effect sensors have less of an impact on the circuit, but are limited in bandwidth compared to the resistive type due to magnetics being messy
@IceWolf (it actually is fun though since you can use the nonlinearity to produce a magnetic amplifer that uses nothing but a ferrite core and some wires, you can control the amplitude of a high-frequency signal on one winding by applying a low-frequency signal on another winding that's just enough to partially saturate the core)
@IceWolf also magnetic current sensors are less accurate than resistive ones, especially at low currents and double especially with any DC bias even if you're just looking at the AC component of the current because! surprise! plain ol' ferrite and electrical steel are nonlinear! fun!