Design of a high-efficiency dual-band class-J/J power amplifier considering concurrent-mode input drive

This article analyses concurrent dual-band Class-J/J power amplifiers (PAs) with simultaneous input drive at both bands. Although it is well known that the Class-J PA has the same performance regarding the efficiency compared with the conventional Class-B PA, in this article, we show that concurrent-mode efficiency of Class-J/J dual-band power amplifier is higher than the Class-B/B counterparts much closer to their single-mode efficiency. Furthermore, it has been explained that the performance of concurrent operation of dual-band PAs is highly dependent to the design space of PA load reactance at intermodulation terms. We also explore that at intermodulation frequencies the design space includes an efficiency degradation region occurring around a specific impedance, which should be avoided when designing for concurrent operation mode. The dependency of the concurrent-mode efficiency to the nonlinearity performance of the transistor output capacitance is also considered. A concurrent dual-band Class-J/J PA operating at 1.842 and 2.655 GHz bands is implemented, where the harmonic and intermodulation control networks are designed based on closed-form equations. Measured results reveal that about 60% balanced concurrent-mode efficiency can be achieved, which outperforms recently reported counterparts. At the lower and upper bands, output powers of 41 and 40.5 dBm and efficiencies of 73.5% and 71.7% are obtained, respectively.