| 摘要 |
A MOSFET contains a voltage clamp including one or more diodes which connects its gate and source. The voltage clamp is designed to break down at a predetermined voltage and thereby protects the gate oxide layer from damage as a result of an excessive source-to-gate voltage. One embodiment includes a second voltage clamp connected between the gate and source terminals of the MOSFET and a resistor connected in series with the first voltage clamp between the gate and source terminals. The second voltage clamp breaks down at a higher voltage than the first voltage clamp and provides a second level of protection, since the voltage across the series combination of the first voltage clamp and resistor cannot exceed the breakdown voltage of the second voltage clamp. The MOSFET and voltage clamps are preferably integrated in the same die, with the voltage clamps consisting of diodes formed of N and P regions in a polysilicon layer. The breakdown voltages of the clamps can be adjusted by varying the arrangement of the diodes and by varying the breakdown voltage of the individual diodes. <IMAGE> |
