Techniques for efficiency enhancement in switched-capacitor DC-DC converters

DC-DC power converters are the most commonly used power management modules that can step-up or step-down the time-varying input DC voltages to regulated DC output voltages. Switched-capacitor (SC) DC-DC converters are commonly used for power delivery when inductors are not preferred under certain applications or when low-cost small-volume DC-DC converters are needed due to the fact that off-chip capacitors are less expensive and smaller than inductors. In addition, SC DC-DC converters have the potential to be fully integrated on chip especially when they are used to deliver small output current of less than 100s of micro-ampere. They can either step up or step down the input supply voltage via controlling different conversion ratios in the power stage.;Driven by the demand for effective power delivery in emerging applications such as providing higher supply voltages to flash memories and EEPROMs and the transcutaneous power transmission in biomedical implants, SC DC-DC converters are becoming more important nowadays as they can deliver power without using any inductor for minimizing the EMI noise and have the potential to be fully integrated for cost reduction.;In the first part of the thesis, a new charge pump (CP) architecture is introduced, analyzed and verified for flash memories and EEPROM applications via dynamically controlling gate and substrate terminals of each pMOS pass transistor in the CP circuit. In the second part of the thesis, an auto-reconfigurable 2x/3x CP for transcutaneous power transmission is developed. The proposed CP can automatically configure its own voltage conversion ratio according to different input voltages such that a DC/DC regulator can maintain high power efficiency under coupling variations. For further improving the power efficiency and the area efficiency of the SC DC-DC converter in transcutaneous power transmission, a 2x/2.5x/3x/4x SC DC-DC regulator is also proposed. The proposed SC DC-DC regulator has a larger number of conversion ratios to better maintain high power efficiencies under the input voltage variations and uses constant on-time control to eliminate the need of an off-chip capacitor and a linear regulator for better area efficiency.