Output buffer that can prevent drain-source voltage of transistor from briefly exceeding nominal voltage

Abstract

An output buffer includes a first P-type transistor, a second P-type transistor, a first N-type transistor, a second N-type transistor, a control circuit, and a tracking circuit. The second P-type transistor and the first P-type transistor are coupled between a supply voltage and a pad, and the second N-type transistor and the first N-type transistor are coupled between a ground voltage and the pad. The control circuit is arranged to generate two first gate control signals according to a control signal for controlling the first P-type transistor and the first N-type transistor. The tracking circuit is coupled to the pad, and is arranged to generate a second gate control signal according to the output signal for controlling the second P-type transistor or the second N-type transistor.