Symmetric 𝔼ven Capacitive converter - The S𝔼C converter
Here, we aim to provide an experimental demonstration of a Symmetric 𝔼ven Capacitive converter operating at 15 MHz with a DC input voltage of \(V_{DC}=25\) V using the components listed in the table below. The load consists of a variable resistor \(R_L\), assumed to be perfectly decoupled by a capacitor \(C\), such that the output voltage \(V_{out}\) across this load remains constant.
| Name | Value | Reference |
|---|---|---|
| Switch | GS61008P | |
| Diode | IDD06SG60CXTMA2 | |
| \(L_1+1/\omega^2C_s\) | 400 nH | homemade, AWG16 wire |
| \(C_1\) | 1000 pF | M100B471JT200XT |
| \(C\) |
2 x 1 µF CKG57NX7R2E105M500JH (ceramic) 2 x 0.2 µF CB047G0104JBC (film) |
|
| \(R\) | variable | 325 Ω – 2 A sliding rheostat |
| \(C_s\) | 385 pF | Parasitic capacitance of the switch |
| \(C_d=C_s\) | 385 pF |
Junction capacitance of the diode (25 pF) + 2 x 100B181JTN1000XC100 (360 pF) |
Note that the DC input voltage source was decoupled using two CKG57NX7R2E105M500JH ceramic capacitors and two CB037E0104KBA film capacitors. Similarly, the load was decoupled using two CKG57NX7R2E105M500JH ceramic capacitors and two CB047G0104JBC film capacitors (In a moment of desperation, we added 2 × 180 pF of 100B181JTN1000XC100 silicon RF capacitors at the output, as shown in the video, hoping to attenuate high-frequency disturbances—without any significant effect.)
In our case, and given the setup parameters, we can calculate the theoretical value of the DC output current as:
\[I_{out}=\frac{2}{\pi}\cdot\omega\cdot C_s\cdot V_{DC}=\frac{2}{\pi}\cdot2\pi\cdot 15e^6\cdot 385e^{-12}\cdot 25=0.58\text{ A} \]
Two photos of the converter are shown below. It is worth noting that the setup presented here is exactly the same as the one used during the experiment and shown in the video below.
Video of the experiment
The two figures below show the variation of the output current \(I_{out}\) as a function of the output voltage \(V_{out}\), as well as the variation of the duty cycle \(D\) of the control signal applied to the transistor, obtained by measuring its conduction time, also as a function of the output voltage \(V_{out}\). The theoretical variations of these two quantities, obtained through analytical modeling (see the “Overview” section), are included on the same graphs for comparison.
