## 2 Simulations Results
The effect of these parasitic elements can be compensated by introducing an additional inductance, Ls1, in the voltage measurement circuit as shown in Figure 5. The proposed network is the dual method that commonly is applied on attenuated voltage probes of the oscilloscope. In this case, a capacitor in parallel to the voltage divider compensates for the input capacitance of the oscilloscope plus the stray capacitance of the connection cable. Thanks to this method the frequency response of the circuit become flat and no overshoot or undershoot are observed. Figure 4: Simulated drain voltage and drain current waveforms measured during the short circuit test at \(\mathrm{V_{DS}}\) = 100 V and \(\mathrm{V_{GS}}\) = 6 V. I(d) represents the actual current, \(\mathrm{I_{sh}}\) the current obtained by using the resistive shunt. Figure 5: Simulated circuit with compensation network. In this work we propose a similar method to compensate the effects of stray inductance. The value of the additional inductance can be calculated by analyzing the total impedance of the circuit. In particular, the time constant of the shunt (Ls/R2) must be equal to that of the branch Ls1, R9 and R10 resulting in  
\[\text{Ls1}=\frac{\text{Ls}}{\text{R2}}\ (\text{R9}+\text{R10}) \tag{1}\]  
This result is easily justified if we look at the two circuits of Figure 6. In both cases, the upper part of the circuit of Figure 3 is schematised as a current generator that injects the drain current into the measurement circuit. In Figure 6a the case of the resistive shunt is considered including the effects of the parasitic inductance Ls. In the circuit of Figure 6b, we have inserted the compensation inductance Ls1. The output voltage Vo, calculated across the resistance R10 in the frequency domain results for the circuit (a) in  
\[\text{Vo}(\omega)=\frac{\text{R2}+j\omega\text{Ls}}{\text{R9}+\text{R10}}\ \text{R10}\ I(\omega) \tag{2}\]  
and it depends on both the value of the inductance Ls and the frequency. For the circuit of Figure 6b, the output voltage is obtained as  
\[\text{Vo}(\omega)=\frac{\text{R2}\ \Big{(}1+\frac{j\omega\text{Ls}}{\text{R2}} \Big{)}}{(\text{R9}+\text{R10})\Big{[}1+\frac{j\omega(\text{Ls}+\text{Ls1})} {\text{R2}+\text{R9}+\text{R10}}\Big{]}}\ \text{R10}\ I(\omega) \tag{3}\]  
By appropriately choosing the value of the inductance Ls1, it is possible to make the coefficients of the imaginary parts equal. In this case, Equation (3) is simplified and the relationship between voltage and current becomes purely resistive. Considering the resistance and inductance values of the circuit of Figure 5 this corresponds to the insertion of an inductor Ls1 = 27.27 \(\mu\)H.  
Figure 7 reports the result of the PSpice simulation in this last case. In the figure, the waveform in green, \(I_{\text{shcomp}}\), represents the current measured using compensated shunt that is perfectly superimposable to the drain current of the DUT I(d). Moreover, we can observe that no additional time constant is introduced, as in the case of the standard RC network of oscilloscope probe. Figure 3:0 Schematic of measure circuit considering parasitic inductance Ls (**a**) and the compensation parameter Ls1 (**b**). This solution, although simple, requires the insertion of a rather high compensation inductance in most practical cases not available. This problem can be overcome by using a two-steps compensation network such as that of Figure 3:1 In this case, the insertion of a low-value resistor (1 \(\Omega\)) allows us to work with an inductance of hundreds of nH. The results on the measured current coincide with the one-step network and are not reported for the sake of brevity.