# Parasitic-Based Active Gate Driver Improving the Turn-On Process of 1.7 kV SiC Power MOSFET
## 4 Experimental Verification  
After the simulation study, the proposed AGD was verified by means of experiments--the simplified main electrical circuit of the proposed AGD for the MV SiC MOSFET is presented in Figure 6. After the simulation research and datasheet-based calculations, it was concluded that the \(V_{\text{Ls}}\) voltage will be in the operational range of the integrated electrical circuits (0/5 V) after adequate signal conditioning. The AGD feedback loop is provided by the connection of the filtering circuit of the AGD to the power source \(S\) of the DUT. All depicted voltage levels in Figure 6 are referenced to the potential of the Kelvin source \(S_{\text{Kelvin}}\). During the short switching time of the chosen SiC MOSFET with high-level power turn-on conditions, \(V_{\text{Ls}}\) is filtered by ferrite beads (FBD) from high-frequency noises to prevent damaging the vulnerable logical gates. The filtered signal is then delivered to the operational amplifiers circuit. In this particular case, two LM-7171 high-speed operational amplifiers were used in the differential configuration. The purpose of this stage is to separate the measuring signal into two independent measuring paths and to add the offset to both of them. Two measurement paths are the reason to have independent signal loops for sensing \(t_{1}\) and \(t_{2}\) (see Figure 2). The outputs of the amplifiers are connected to low-propagation delay comparators, TLV3501 (4.5 ns), with the reference voltages \(V_{\text{ref1}}\) and \(V_{\text{ref2}}\). Values of \(V_{\text{ref1}}\) and \(V_{\text{ref2}}\) were obtained based on the datasheet of the device (switching speeds and \(L_{\text{S}}\) = 15 nH). Note that these parameters may differ and the driver applied for different modules may need additional tuning. For the considered CAS300M17 BM2, approximate maximum and minimum values of \(V_{\text{Ls}}\) should be in the range \(\pm\)7.8 V for \(R_{\text{G}}\) = 20 \(\Omega\). However, this value is too high to be provided for the TLV3501 comparators (0/5 V). Operational amplifiers suppressed this voltage and added offset, meaning that their output signals have maximum values of 5 V and minimum values of 0 V. It means that in steady state, where the device is not switching, the outputs of the amplifiers are 2.5 V. Thus, \(V_{\text{ref1}}\) has a value of 2.5 V + 10% \begin{table}
\begin{tabular}{c c c c} \hline \hline \(V_{\text{DD}}\) & \(I_{\text{0}}\) & \(E_{\text{on}}\)**CGD** & \(E_{\text{on}}\)**AGD** \\ \hline
700 V & 170 A & 24.0 mJ & 19.4 mJ \\
700 V & 270 A & 46.2 mJ & 36.5 mJ \\
900 V & 170 A & 32.4 mJ & 27.4 mJ \\
900 V & 270 A & 65.5 mJ & 45.9 mJ \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The turn-on energy losses of CGD and AGD comparison from the simulation study. Figure 5: The turn-on cycle of the SiC MOSFET from module CAS300M17 BM2 using AGD. \(V_{\text{DD}}\) = 700 V, \(I_{0}\) = 270 A.  
of 2.5 V, which is 2.75 V, and its role is to identify when \(i_{\rm D}\) starts to rise during the turn-on cycle. The 10% tolerance secures it from any inappropriate disturbances that could cause switching of the comparator due to the parasitic in the device. On other hand, the \(V_{\rm{ref2}}\) role is to sense moment \(t_{2}\) (see Figure 2). The value of this reference voltage was set to 4 V after approximated calculations of the expected \(V_{\rm{Ls}}\) value. \(t_{2}\) is sensed based on the change in the operational amplifier output from a value above 2.5 to below 2.5 V, which corresponds to the \(V_{\rm{Ls}}\) change from positive to negative voltages. Comparators are responsible for sensing the \(t_{1}\) and \(t_{2}\) time moments (see Figure 2) of the \(V_{\rm{GG}}\) voltage modification.