A side door for a vehicle includes a folded airbag which inflates upward in response to a side collision of the vehicle, and a cover member disposed above the airbag and covering the airbag. The differential amplifier comprises two differential pairs, each having two amplifying MOSFETs. The particles have a length to thickness ratio of from about 10 to about 1000. The gate dielectric is merged with the depletion trench dielectric between the depletion electrode and the gate electrode.