This paper shows a wideband high power efficiency amplifier with internal package matching. The power amplifier has been designed and realized by using the Continuous Inverse Class-FI approach for wideband applications. In particular, the fundamental as well as the second and third harmonic output terminations have been matched inside the packaged transistor without the use of further external output matching conditions. The realized prototype shows drain efficiencies in the range of 59.5–71% while delivering 42.4–45.7 dBm of output power in the very wide frequency range of 1.8–2.7 GHz.