A low-voltage charge pump for micro scale thermal energy harvesting

For energy harvesting applications, a power management unit (PMU) architecture operating at low input voltages is required. The most critical sub-blocks of such a PMU are the voltage multiplier and the low-voltage clock generator. An ultra-low-voltage exponential gain charge pump (ECP) that serves as a voltage multiplier for such PMUs is analyzed. A low-cost fully-integrated CMOS implementation for the ECP is proposed. Circuit simulations demonstrate a 0.85-0.90 V output for input voltages as low as 150 mV and static loads up to 1.5 μA. The ECP was simulated in Cadence environment using a TSMC CMOS 65 nm process and a total of 5 nF MIM capacitors.