A 3.7 V to 200 V highly integrated DC-DC converter with 70.4% efficiency for portable electrostatic MEMS applications

Laser-based pico projectors are readily available, however to push their integration one step further and include them in smartphones, tablets or car head up displays, new ways to generate the high voltage required by electrostatic MEMS actuators must be proposed to meet smartphones´ small form factor and power requirements. In that context, this paper presents a highly-integrated coupled inductor DC-DC converter that can convert a 3.7 V battery voltage into a 150 V to 300 V output voltage suitable for biasing electrostatic MEMS in portable applications. The fabricated circuit occupies 4.21 mm² in a 0.8 μm 300 V HVCMOS process. To achieve that small active area, a power switch that reduces by up to 79% the switch silicon area requirement has been developed. At 200 V output voltage, the DC-DC converter can deliver up to 500 mW with a peak efficiency of 70.4% which outperforms current highly integrated solutions.