A reconfigurable multi-ratio charge pump with wide input/output voltage range for wireless energy harvesting system

Abstract

A charge pump (CP) with reconfigurable multi-ratio is proposed for wireless energy harvesting system, which has almost eight ratios with small step to suit for wide input or output voltage range applications. Six flying capacitors are adopted to generate different conversion ratios (CRs) from ×0.25 to ×2 with step of 0.25. The CR of the CP is determined by input voltage and on-chip control unit. Thus, an almost constant output voltage is obtained in a wide input voltage range. Besides, the MOS switches of the CP are driven by a two-phase non-overlapping clock to reduce quiescent current and improve the power conversion efficiency (PCE). As a result, a configurable CP is achieved by using a standard 0.35 μm CMOS process with 1.7 mm2 die area (include PADs.) The output voltage of the CP can be kept almost constant at 3.6 V when Vin varies from 1.77 V to 4.80 V. The PCE is over 80% no matter which CR is, and the maximum PCE of 93.8% is achieved when Vin=3.6 and CR=1 @ 1.2 KΩ load resistance. The wide input/output voltage range and PCE of the proposed CP shows its good practicality for DC-DC converter of wireless energy harvesting system.