## 4 Experimental Verification  
Figure 13a shows the Gerber file of the daughter board containing information of the GaN-GS66508 T-based, half-bridge circuit and the pickup coil of Model-E described  
Figure 12: Interference of the external conductor perpendicular to the sensor coil. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Coil Type** & \multicolumn{3}{c}{**Vertical Structure (Model-A)**} & \multicolumn{3}{c}{**Horizontal Structure (Model-C)**} \\ \hline Turn number \(N\) & 1 & 2 & 3 & 1 & 2 & 3 \\ \hline Mutual inductance \(M\) [nH] & 0.32 & 0.41 & 0.53 & 1.15 & 1.79 & 2.7 \\ \hline Self inductance \(L_{c}\) [nH] & 9 & 14 & 20 & 7.5 & 13.6 & 23.5 \\ \hline \(L_{c}/M\) & 28.1 & 34.1 & 37 & 6.52 & 7.59 & 8.7 \\ \hline Coupling capacitance [pF] & 1.41 & 1.72 & 2.09 & 0.46 & 0.54 & 0.65 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Influence under different turn-numbers with the FEM. in this paper. This layout is a half-bridge structure for the double pulse test [35], and a pickup coil is configured to measure the primary current flowing on the bottom layer of the PCB. Figure 13b shows the entire double pulse test set, including an active integrator, digital signal processor board, inductor, and mainboard, which is vertically coupled with the daughter board through the connector. Moreover, as a commercial current sensor for comparison and verification with the pickup coil, a shunt resistor sensor was used. The experiment was conducted based on the parameter values of each coil and integrator configuration, as shown in Table 6. In the case of the magnetic flux incident surface, the maximum width allowed in the PCB space was set according to the parameter analysis, and the distance between the coil and the trace was set to an optimum value of 0.65 mm. In the case of the operational amplifier (op-amp) constituting the integrator, LM7171 is manufactured by Texas Instruments, Dallas, Texas, USA with a high slew rate of 4100 V/us, and the wide unity-gain bandwidth of 200 MHz was selected. Furthermore, Table 7 lists the experimental conditions for the double pulse test circuit (DPT) test. \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Values** \\ \hline Mutual Inductance & 3.2 nH \\ Self-Inductance & 20.5 nH \\ Self-Capacitance & 5.56 pF \\ Self-Resistance & 0.03 \(\Omega\) \\ Coupling Capacitance & 0.69 pF \\ Magnetic Flux Incident Areas & 11.7 mm\({}^{2}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Circuit parameters of the current sensor. Figure 13: Double pulse test set: (**a**) Gerber file of the daughter board containing the pickup coil, (**b**) overall test board, and (**c**) double pulse test circuit (DPT). Figure 14 shows the pickup coil output value without an integrator when the switch is operated in a DC voltage environment of 100 V and 200 V. From the experimental results, the positive peak values of the output values when switched on and off in a 100 V DC voltage environment are 9.1 V and 7.7 V, respectively, and the positive peak values of the output values when switched on and off in a 200 V DC voltage environment are 9 V and 6.2 V, respectively. Therefore, the peak value is generally lower in a DC environment of 200 V than at 100 V, and it is higher in the switch-off period than in the switch-on period. \begin{table}
\begin{tabular}{c c} \hline
**Parameter** & **Values** \\ \hline Distance between Trace and Coil & 0.65 mm \\ Bandwidth & 590 MHz \\ Damping Resistance & 100 \(\Omega\) \\ Integrator Resistance & 70 \(\Omega\) \\ Integrator Capacitance & 470 pF \\ \hline \end{tabular}
\end{table} 
Table 6: _Cont._  
Figure 14: Measured output of a pickup coil following switch behavior: (**a**) switch-on condition at 100 V DC voltage, (**b**) switch-off condition at 100 V DC voltage, (**c**) switch-on condition at 200 V DC, and (**d**) switch-off condition at 200 V DC voltage. Figure 15 shows the result of transient response analysis in the switch-on section through a double pulse test.