Doldinger was born in Berlin, Germany,[1] and entered a Düsseldorf conservatory in 1947, originally studying piano and then clarinet,[2] graduating in 1957.

In his student years, Doldinger gained professional performing experience, starting in 1953 in the German Dixieland band The Feetwarmers, and recording with them in 1955.

[3] At various times members of Passport included Peter O'Mara (guitar), Roberto DiGioia (keyboards), Patrick Scales (bass, since 1994), Ernst Stroer (de:Ernst Ströer) (percussion, since 1989), Christian Lettner (drums, since 2000), Michael Hornek (keyboard since 2009), Biboul Darouiche (percussion, since 1995) and others.

[4] The first true Passport album had strong ties to Amon Düül II, containing contributions from Olaf Kübler, Lothar Meid and Jimmy Jackson.

[1] He also composed the musical theme of the long ongoing German-Austrian-Swiss series, Tatort (Crime scene).