Fig. 1. (Color online) Two-way PDPA’s. (a) Simplified model; (b) drain efficiency performance; (c) λ/4 T-line based IIN’s ITR.

Fig. 2. (Color online) Typical methods of two-way power combiner. (a) Series power combiner; (b) parallel power combiner.

Fig. 3. (Color online) The characterization of pseudo-differential CS amplifier. (a) Simplified circuit; (b) small signal equivalent circuit; (c) simulated Z_opt* vs transistor’s multiplier.

Fig. 4. (Color online) Transformer-based two-way power combiner for Doherty PA. (a) Series power combiner; (b) parallel power combiner.

Fig. 5. (Color online) Frequence performances of Zmain. (a) Without LC resonators; (b) with LC resonators.

Fig. 6. (Color online) Simplified form of (a) SDPA and (b) SDPA’s IIN; (c) inversion paths of ideal λ/4 T-Line and IINs; (d) IINs based on lumped-elements.

Fig. 7. (Color online) Simulated (a) S₂₁ and (b) S₁₁ of different lumped-elements based IINs.

Fig. 8. (Color online) Equivalence relations between C−L−C π network and (a) the transmission line; (b) the lumped-element model of transformer; (c) coupler-based network.

Fig. 9. (Color online) The implementation procedure and result of the distributed IIN. (a) The multi-step IIN; (b) the insertion of two ideal baluns; (c) the final replacement.

Fig. 10. (Color online) IIN’s phase shift performance at (a) 6 dB PBO; (b) 0 dB PBO; and (c) AM–PM distortion.

Fig. 11. (Color online) The simulated effective load impedances of two paths at (a) 26 GHz; (b) 27 GHz; (c) 28 GHz; (d) 29 GHz.

Fig. 12. (Color online) The EM model of series-Doherty power combiner.

Fig. 13. (Color online) The simulated passive efficiency of the output network at (a) 26 GHz; (b) 27 GHz; (c) 28 GHz; (d) 29 GHz.

Fig. 14. (Color online) The schematic of the proposed (a) SDPA; (b) ABN; and (c) the frequency response of ABN.

Fig. 15. (Color online) The EM model of (a) QHC; (b) input IMB; (c) inter IMB.

Fig. 16. (Color online) Die micrograph of the proposed SDPA.

Fig. 17. (Color online) Measured S-parameters.

Fig. 18. (Color online) Simplified (a) small CW signal; (b) large CW signal; (c) modulation measurement setups.

Fig. 19. (Color online) Measured P_sat and OP1dB vs freq (limited by signal generator, results only cover frequencies below 30 GHz).

Fig. 20. (Color online) Measured peak/OP1dB/6dBPBO PAEs vs freq (limited by signal generator, results only cover frequencies below 30 GHz).

Fig. 21. (Color online) Measured output power and PAE at (a) 24 GHz; (b) 26 GHz; (c) 27 GHz; (d) 28 GHz.

Fig. 22. (Color online) Measured constellations/spectrums under 200 MHz 64-QAM at (a) 22 GHz; (b) 27 GHz; (c) 31 GHz.

Fig. 23. (Color online) Measured results at 27 GHz under (a) 100 MHz 256-QAM; (b) 600 MHz 64-QAM; (c) 2 GHz 16-QAM.