A new design for mode transfer-based harmonic tuned power amplifier (MHPA)

Available onlineThis paper presents the design, implementation and measurement results for a 0.8–2.1 GHz Mode transfer-based Harmonic tuned Power Amplifier (MHPA). The design based on a new combination of the hybrid modes. The proposed design approach uses the mode transfer technique to combine two harmonic tuned power amplifier modes, i.e., classes F3 and F3-1, in order to obtain a broadband hybrid mode PA. First, theoretical limitations of maximum attainable Fractional Bandwidth (FBW) in a single mode harmonic tuned PA (HTPA) are investigated where we have n harmonic impedances and there is no overlapping between harmonics. Then, mode transfer technique is applied to overcome bandwidth restriction of F3 and F3-1 modes of HTPA. As a result, the maximum FBW in a single mode HTPA with 3 harmonic impedances is improved from 40 % to 66 % (equivalent to one octave) when it being used in a hybrid structure. To evaluate the proposed design approach, a broadband PA, which is working at one octave bandwidth (1–2 GHz), is designed and fabricated. Performance of the designed MHPA is acceptable at the 0.8–2.1 GHz frequency band. Experimental results show that the designed MHPA achieves 89.9 % maximum and 76.3 % average drain efficiency in the 0.8–2.1 GHz frequency band.