Abstract: The present invention concerns an output buffer circuit with a switchable common mode output voltage level. An output buffer circuit according to the invention comprises a plurality of output stages (1,2) for driving a symmetrical transmission line (RT). A power supply circuit (U1,U2) provides an upper power supply potential (Vbh) and a lower power supply potential (Vbl) for the output stages (1,2). The power supply circuit is adapted to provide the lower power supply potential (Vbl) at different levels in accordance with a configuration signal (En). Depending on the configured lower power supply potential (Vbl) of the output stages (1,2) at least one of the output stages is activated or inactivated in order to compensate the effect of the lower power supply potential (Vbl) on the output impedance of the output stages (1,2).