Concurrent planar multiharmonic dual-band load coupling network for switching-mode power amplifiers

This paper presents a concept to design a compact planar multiharmonic load transformation network (MHLTN) for the realisation of highly efficient dual-band power amplifiers (PAs). The proposed MHLTN consisting of only transmission-lines can precisely achieve impedance terminations at two distinct nonharmonic frequencies including up to three harmonics without switches or tuning elements. High impedance stubs are deliberately inserted at particular sections of the network for the harmonic frequency termination to be controlled. The topology was applied to implement a class-E PA using a GaN High Electron Mobility Transistor (HEMT) in a hybrid design for GSM1810 and LTE2655 operation. The measured impedances of the passive switchless MHLTN for a dual-band class-E load coupling network are in good agreement with simulation results. With a dual-band input matching network, the measurement results have shown 78.4% and 61.3% of peak power added efficiency (PAE) with an associated output power of 37.8 dBm and 36.9 dBm in the lower and upper band, respectively.