A Battery to 70-V Hybrid Boost Converter Achieving 14-to-20 VCR for Piezoelectric Actuators

This brief presents a hybrid boost DC-DC converter for driving piezoelectric actuators that overcomes the frequency limitation of traditional boost converters and the 3-level, double-step-down (DSD) topology when dealing with high conversion ratios (VCR). The proposed converter combines the benefits of conventional hybrid Fibonacci and Dickson switched-capacitor (SC) converters to achieve high VCR with fewer capacitors and lower-voltage-rating switches. Two inductors are used to reduce DC resistance (DCR) loss and achieve charge and current balance. The converter operates as a
$14\times $
boost circuit with a duty ratio (D) as high as 0.5. With the SC stages reducing the voltage stress of inductors, only two small inductors are required to complete voltage conversion, reducing the inductor current ripple. This brief was fabricated in the 180nm 1P6M BCD process. It can deliver a maximum load current of 2mA to an output voltage of 40-70V with a standard battery input voltage of 2.5-5V. The measurement results show a 54.8% peak efficiency and 2.312mW/mm3 power density, which are higher than the commercial products and the prior arts.