A pentode transistor is any transistor having five active terminals.
Early pentode transistors One early pentode transistor was developed in the early 1950s as an improvement over the point-contact transistor. A point-contact transistor having three emitters. It became obsolete in the middle 1950s. Pentode field-effect transistors having 3 gates, similar to vacuum tube pentodes have also been described
Modern pentode transistors Triple emitter transistor in three input transistor-transistor logic gates. Triple collector transistor in three output integrated injection logic gates. Field effect transistor having three gates. References