High-Voltage-Tolerant Level Converter for Embedded Complementary Metal-Oxide-Semiconductor Nonvolatile Memories

摘要

In this paper, a high-voltage-tolerant level converter for embedded complementary metal-oxide-semiconductor (CMOS) nonvolatile memories is proposed. The level converter circuit includes a high-voltage driver and a level shifter, which makes use of 1 x V_(dd) devices to generate 2 x V_(dd) signals without overstress. In addition, it features one select signal to make the level converter have the tri-state. The high-voltage driver efficiently stacks two transistors to allow a voltage drop of V_(dd) for each transistor, which helps maximize the driving ability. The level shifter using the cross-coupled structure with small metal-oxide-semiconductor (MOS) capacitors drives the high-voltage driver without the "preconditioning" process. The level converter implemented using the 0.35 um CMOS process on the area of 0.002 mm2 was measured at V_(dd) = 3.5 V to generate the output signal swinging from 0 to 7 V.