High current driving charge pumps in distributed biomedical implants using silicon-on-sapphire technology

This paper presents two highly efficient charge pump designs, one positive and one negative, used in a distributed bioimplant with completely integrated capacitors. The system is designed using silicon-on-sapphire (SOS) technology CMOS transistors to triple the voltage swing available at the chip-scale implant. The high power efficiency and high voltage conversion ratio of the system is obtained by selectively controlling the transistor switches in the current path to reduce the reverse current flow. The proposed charge pump design achieves a power efficiency of 83.3% and voltage conversion ratio of 0.95 for a 3 V, 2 MHz input signal and load of 2.5 mA. All performance simulations are done on cadence software customized by the Peregrine Semiconductor Corporation to implement SOS technology.