A new transformer-based startup scheme with novel voltage monitors for energy harvesting

A new transformer-based startup scheme with novel voltage monitors developed in UMC 0.18μm CMOS process is presented in this paper. The startup process is divided into two modes: oscillation and constant duty cycle flyback, which greatly reduces startup time and only needs a small depletion-mode power transistor. Also a novel voltage monitor here can generate switch point voltage with very small temperature coefficient. Simulation results show that the startup time are 0.1s (V
_IN
=300mV) and 3s (V
_IN
=50mV). The switch point voltage is 1.1V with temperature coefficient of only 0.33mV/°C.