| 摘要 |
Protection circuitry is provided to protect a MISFET, particularly a short-channel MISFET, from the punch-through phenomenon. To protect a MISFET QE1 a protection circuit having a gate controlled diode GCD is connected to provide a by-pass path for excessive voltage charges which would otherwise pass from a high voltage power supply terminal VDD to the drain of the MISFET QE1. GCD has a breakdown voltage, set by applying a predetermined gate voltage Vg to a gate thereof, less than a punch-through voltage of the MISFET QE1. When an excessive voltage is applied which would otherwise cause a punch-through phenomenon in QE1, CGD breaks down first to provide a by-pass charge path and thus protect the MISFET QE1. |
