Patent ID: 8884337

Claim:
An output buffer, comprising: an active region; a first metal oxide semiconductor transistor, comprising: a first gate, formed along a first direction on the active region in a plan layout view of the output buffer; a first source, formed at a first side of the first gate; and a first drain, formed at a second side of the first gate; and a second metal oxide semiconductor transistor, comprising: a second gate, formed along a second direction on the active region in the plan layout view of the output buffer, the first direction being substantially perpendicular to the second direction; a second source, formed at a first side of the second gate; and a second drain, formed at a second side of the second gate, the first drain being connected to the second drain; and wherein a punch through voltage of the first metal oxide semiconductor transistor is higher than a punch through voltage of the second metal oxide semiconductor transistor.