A Novel Darlington Structure Power Switch Using a Vacuum Field Emission Transistor

This study proposes a power switch combining a vacuum field emission transistor (VFET) as a controlled transistor with a power bipolar Darlington transistor (DT) as an output transistor, termed the VFET–DT structure. Compared to the MOS–bipolar Darlington power switch, the VFET–DT structure achieves an extremely low off-state leakage current and high-voltage withstanding capability due to the field emission mechanism of the VFET. It can also avoid the Miller effect that results from incorporating the load resistance into the feedback loop. The high gain and high-power capacity can be achieved due to the cascade of DT. The device’s typical electrical characteristics were theoretically investigated by simulation. The VFET–DT structure exhibited a high-power capacity of 20 A and 400 V with a minimum conduction voltage drop of 1.316 V and a switching frequency of 100 kHz. The results demonstrated that the combination of a vacuum transistor and a solid-state transistor combines the advantages of both and benefits the performance of the power switch.