Polarization Switching DC-to-DC Converters

Abstract – On-chip DC-to-DC converters are critical to ensure regulated voltage for a variety of DC applications, including automotive and personal computer products. The converters have historically been limited to low power applications due to the size and cost constraints involved with the desire to have the converters integrated with the application circuit. The latest technology involves using switched-capacitors to allow for lower cost and monolithic integration. A new DC-to-DC converter design, utilizing a ferroelectric (FE) capacitor is researched, fabricated and tested. The inclusion of a FE, switched-capacitor results in an increase in the converter's output voltage due to the high dielectric constant (high-k) of the capacitor in conjunction with the resulting switching current as the polarization of the capacitor is reversed. In fact, the FE capacitor's effective capacitance resulting from the polarization switching provides the same behavior as a linear capacitor that is approximately 10 times the size (with respect to capacitance) as the FE capacitor. A proposed ferroelectric-based DC-to-DC step-down converter is analyzed, simulated, fabricated and tested. The results show the FE capacitor-based converter provides an output voltage and output impedance advantage over linear capacitor-based converters for equivalent capacitance levels.