This paper presents the theory and design methodology of broadband RF-input continuous mode load modulated balanced power amplifier (CM-LMBA) by introducing the continuous mode output matching networks in the LMBA architecture. It is illustrated that the continuous mode impedance condition can be achieved by properly adjusting the phase difference between the different PA branches in the proposed CM-LMBA during the entire load modulation process. An RF-input CM-LMBA with 1.45-2.45 GHz bandwidth using commercial GaN transistors is designed and implemented to validate the proposed architecture. The fabricated CM-LMBA attains a measured 11.2-13.4 dB gain and around 40 Watts saturated power. Power added efficiency (PAE) of 46.4-56.5% and 43.2-50.3% is achieved at 6 dB and 8 dB output power back-off throughout the designed band. When driven by a 100 MHz OFDM signal with 8 dB peak to average power ratio (PAPR), the proposed CM-LMBA achieves better than -46 dBc adjacent channel leakage ratio (ACLR) and higher than 45% average PAE after digital pre-distortion at 1.8 GHz and 2.1 GHz.

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This article presents a novel waveform engineered sequential load modulated balanced amplifier (W-SLMBA) that uses a continuous Class-F −1 control amplifier (CA) to manipulate the impedance trajectory of the balanced amplifier (BA). It is demonstrated that the use of the continuous Class-F −1 CA can trigger a unique impedance load modulation mechanism by which the fundamental impedance of the BA is shaped by the varying second-harmonic load reactance of the CA. Theoretical derivations reveal that this special load modulation yields extended design space for the LMBA, in which high efficiency can be achieved over wide bandwidth and output power back-off (OPBO). A prototype operating from 1.80 to 2.75 GHz is designed following the proposed theory. The implemented LMBA achieves a measured drain efficiency (DE) of 60.2%-68.3% at saturation and 51.8%-69.0% at 8-dB OPBO. When tested with a 100-MHz long-term evolution (LTE) signal having peak-to-average power ratio (PAPR) of 8 dB, the proposed LMBA achieves 50.2%-59.1% average DE and better than −45.1-dBc adjacent channel power ratio (ACPR) across the target bandwidth after digital predistortion (DPD).

This paper proposed a new dual-band dual-polarized array antenna operating at 28 GHz and 38 GHz for 5G communication applications. Three stacked patches are adopted to achieve the dual-band operation. The lower band from 27.48 to 28.50 GHz is achieved by using the lower large patch, which is couple-fed by the middle patch. While the upper band from 36.94 to 40.43 GHz is achieved by using the middle and upper patches. The two patches resonant at 38 and 40 GHz respectively and the two resonant modes coupled together, which greatly enhances the upper band. To increase the polarization isolation in the lower band, a shorting pin connecting the lower patch and ground is utilized. Taking advantages of the multi-layer technology, the position of the vertical feeding probe between the middle patch and lower patch is slightly shifted to ensure the good impedance matching in both lower band and upper band. For the antenna element, the simulated-12 dB bandwidths are 27.48-28.50 GHz and 36.94-40.43 GHz for the two bands, respectively. The in-band gains are over 6 dBi in the lower band, and over 4 dBi in the upper band. For the 2×2 antenna array, the isolations are better than 20 dB in both bands.

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