an input - output receiver includes a receiving terminal , a first n - type metal - oxide - semiconductor transistor , a reformation circuit , and a compensation unit . the receiving terminal is coupled with an external voltage signal . the first nmos transistor has a source electrode coupled with the receiving terminal and a gate electrode coupled with a first power supply voltage . the reformation circuit is configured to reform a voltage signal transmitted from a drain electrode of the first nmos transistor . the compensation unit includes a first pmos transistor , a second pmos transistor , and a second nmos transistor . moreover , the compensation unit is configured to provide a compensation voltage to a voltage signal at the drain electrode of the first nmos transistor thereby a maximum level of the voltage signal at the drain electrode of the first nmos transistor reaches the first power supply voltage .