A novel harmonic tuning circuit (HTC) for Class-E power amplifier is presented. Conventional HTCs unavoidably use long transmission lines (TLs) to tune the 2nd and 3rd harmonics simultaneously, resulting in increased circuit size and decreased bandwidth. Such redundant circuit configuration arises from the characteristics of the electromagnetic waves in microstrip lines. It is shown that, using two CRLH TL stubs, the HTC can be designed without redundancy and thus with significantly reduced circuit size. The HTC was applied to a 2-GHz GaN HEMT Class-E power amplifier, demonstrating output power of 38.6 dBm, drain efficiency of 78.5% and PAE of 74.0%.