Simplifying the design of harmonic-suppressing power amplifiers adopting capacitance-splitting method

In this paper, an effective strategy for harmonic-suppressing power amplifier (HS-PA) design is proposed. To ease the design of HS-PAs with harmonic-suppressing output matching networks (HS-OMN), the capacitance-splitting method is proposed to tactically incorporate harmonic-reflecting λ/4 stubs into the HS-OMN. Benefits from the proposed method, normally complex iterative tunings on HS-OMN parameters are avoided in implementing HS-PAs. Two prototype designs are presented to verify the effectiveness and generality of the proposed methodology. One prototype operates in Class AB, which achieves saturated output powers of 47.8 ± 0.2 dBm, peak efficiencies of 70 ± 3%, and harmonic suppressing ratios of better than 70 dB on both the second and third harmonics over 2.3–2.7 GHz. Another prototype is a Doherty HS-PA, which achieves a saturated output power of 43.2 dBm, saturated/6 dB back-off efficiencies of 77%/63%, and suppression ratio of better than 60 dB on both the 2nd and 3rd harmonics at 1.95 GHz.