A Bulk Current Regulation Technique for Dual-Branch Cross-Coupled Charge Pumps

In this paper an original scheme, exploiting the trans-conductive loop implemented through the bulk terminal of the PMOS transistors of cross-coupled charge pumps, is proposed to achieve the regulation of the output voltage of a charge pump. As compared to the conventional regulation schemes, the proposed one achieves wide regulation ranges in terms of input voltage and clock frequency, while achieving low circuit complexity. The solution is theoretically analyzed and exploited in a design example implemented in a 130-nm CMOS process and supplied by a single silicon photovoltaic cell. Experimental results show the effectiveness of the proposed regulation scheme when operating around the maximum power point. It provides a simple and effective solution with good performance in terms of line and load regulation, equal to 107 μ V/mV and 3.97 mV/μ A, respectively, a power conversion efficiency of about 65% and an outstanding power density of 83 μ W/mm.