Compact harmonic tuning circuits for class-F amplifiers using negative order resonance modes of CRLH stub lines

Extremely compact harmonic tuning circuits for class-F amplifier are realized using composite right-/left-handed transmission line (CRLH TL) stubs. The circuit takes up only a small fraction of the amplifier circuit area and yet is capable of treating four harmonics up to the fifth with a single stub or double stub configurations. This has become possible by using the negative order resonance modes of the CRLH TL, allowing for flexible and simultaneous control of many harmonics by tuning the dispersion curve of the stub line.