A 34 nA Quiescent Current Switched-Capacitor Step-Down Converter with 1.2V Output Voltage and 0–5μA Load Current

Motivated by the ultra-low power design demands of the integrated implantable medical electronics and systems, a switched-capacitor DC-DC converter is presented in this paper. The DC-DC converter is controlled by hysteretic control approach, which has inherently stable and fast loop speed compared with the approach using error amplifier. To achieve higher power efficiency and lower quiscent current, in addition to optimizing the switching frequency and width of the core module of the converter, Low power design methodes are used for the functional module. By operating transistors in the subthreshold region and decreasing operating frequency, the short current and dynamic power can reduce a lot. The converter has designed in 0.18μm standard CMOS technology. It can achieve step down voltage conversion of 1.2V with a ripple voltage of 1.4mV from 2.5V input voltage. A high power efficiency of 88.3% can be achieved at a load current of 3μA. It also produces about 34nA low quiescent current without load, which is suitable for the integrated implantable biomedical electronics.