PhD student Aria Delmar with Advisor A. Stillwell

With power delivery constraints becoming a pressing concern for processor power delivery, integrating the PoL converter into the processor package would allow for a simplified power delivery network and reduce power delivery losses. However, integrating these converters has been difficult to realize. Previous hybrid switched-capacitor power converters have achieved the high-power density and high-efficiency conversion needed for processor PoL applications, but face limitations in chip-level integration due to reliance on magnetics as the output filter. To overcome this limitation, we propose a class of hybrid SCCs featuring a current-sourced input stage and no magnetics at the output.  By keeping the magnetics at the input, the converter design detailed in this paper presents a class of converters capable of a system-on-chip (SoC) or system-in-package (SiP) implementation where magnetics are connected externally at a low-current node.  Figure 4 demonstrates how this implementation reduces how many processor pins must be dedicated to power delive ry. The schematic for this converter design is shown in Figure 5.  Interleaved series-parallel switched-capacitor (SPSC) branches (SPSC A and SPSC B in the figure) connect to the output of a current-type buck (CTB) and operate in a complementary fashion.  The converter has been implemented in a discrete PCB prototype, as demonstrated in Figure 6.

This work is supported by the UIUC ECE Department and the Grainger Foundation.

Figure 4. The proposed current-sourced converter reduces current flowing into the processor package by a factor of n, where n is the number of switched-capacitor levels.

Figure 5. Converter design developed combing the current-type buck (CTB) and series-parallel switched-capacitor (SPSC) topologies. Voltage conversion of Vout=DnVinVout=DnVin, where D is the controllable duty ratio associated with the CTB and n is the number of levels implemented in the SPSC stage.

Figure 6. Discrete prototype of proposed converter where all magnetics are located at input.