A regulated cross-couple charge pump with new charging current smoothing technique is proposed and verified in a 0.18-μm 1.8-V/3.3-V CMOS process. The transient behaviors of 3-stage cross-couple charge pump and the expressions for the charging current are described in detail. The experiment results show that the charging current ripples are reduced by a factor of three through using the proposed new clocking scheme. The voltage ripples in the power supply line, which is connected with the charge pump input, are also smoothed greatly as the filter circuit does. The proposed scheme is used to decrease the smoothing capacitance in the power line of charge pump for reducing the size of implantable devices in biomedical application. In addition, the power efficiency is improved. The proposed cross-couple charge pump can provide 10.5-V output voltage with 3.5-mA output current, and the power efficiency of the charge pump can be up to 69%.
Publication: ZC Luo, MD Ker, WH Cheng, TY Yen, “Regulated Charge Pump with New Clocking Scheme for Smoothing the Charging Current in Low Voltage CMOS Process,” IEEE Trans. on Circuits and Systems I: Regular Papers, vol. 64, no. 3, pp. 528-536, Mar. 2017.