| 摘要 |
A power MOSFET type device, which can include an IGBT or other VDMOS device having similar forward transfer characteristics, is formed with an asymmetrical channel, to produce different gate voltage threshold characteristics in different parts of the device. The different gate voltage threshold characteristics (VTH1, VTH2) can be achieved either by different source region doping concentrations (28(1), 28(2)) or different body region doping concentrations (22(1), 22(2)) subjacent the gate oxide (24), or by asymmetrical gate oxide (24(1), 24(2)) thicknesses (T1, T2). The portion of overall channel affected can be 50 % or such other proportion as the designer chooses, to reduce the zero temperature coefficient point of the device and improve its Safe Operating Area in linear operation, while retaining low conduction loss. Multiple power MOSFET devices with asymmetrical channels can easily be used safely in parallel linear power amplifier circuits. |
