In this paper, the design of a broadband, high-efficiency, and high-linearity Class-J GaN HEMT RF power amplifier (PA) over 1.6-2.6 GHz is explained. The source impedance is conjugatematched to the input impedance of the device resulted from small signal simulation to make a high-gain power amplifier. The load impedance related to the maximum power added efficiency (PAE) and maximum output power is obtained by pulling the only fundamental and second harmonic components over frequency bandwidth. Thus, not only a high-efficiency PA but also a high-linearity PA is formed. The input and output matching networks are implemented by microstrip transmission lines. The theoretical PA designed is optimized using computer-aided simulations. The fabricated PA provides output power in the range of 38-39.9 dBm with 60%-73% PAE and 15-16.3 dB power gain across the band. The worst measured ACLR1 as the PA is fed by the CDMA signal with 1.2288 MHz bandwidth is at a level of −38.6 dBc. A close agreement between the measured and simulation results is observed due to the use of high-order harmonic balance simulator and high-accuracy implementation procedure.

Abstract-In this paper, after a brief review of the previous nonlinear power amplifier (PA) classes including Class-B, Class-F, and Class-J, a novel design theory for high-efficiency and high-linearity microwave power amplifier based on 2nd harmonic component of the drain voltage and current signals is proposed. The new scheme introduces a new nonlinear class which like Class-J tunes only two primary harmonic components but unlike Class-J, the drain voltage is boosted to the maximum four times dc drain voltage. A quasi half sinusoidal waveform for the current and a quadratic sinusoidal waveform for the voltage are thus realized in this class, leading to a minimum waveform overlapping. The new class theoretically provides 93% power efficiency. It is, in fact, an enhanced Class-J with higher power efficiency and better linearity performance.

Abstract:Modern day cellular networks are driven by the need to provide ubiquitous connectivity with very high spectral efficiency to both indoor and outdoor users, hence the need to deploy small cells over conventional macrocells in a Heterogeneous Network (Hetnet) deployment. To alleviate the resulting inter-cell and cross-tier interference, effective intercell interference coordination (ICIC) schemes such as Fractional Frequency Reuse (FFR) are employed, and have been widely studied in perfect geometry network scenarios which are too idealistic and not easily adaptable to the complexity of Hetnets. This work provides an analytical framework for the performance of such FFR schemes in Hetnets with antenna sectorization employed at the macro tier, by leveraging stochastic geometry tools to model base station locations of both macro and femto tiers using the Poisson Point Process (PPP). We study the effects of varying system parameters and consider cross-tier femto interference commonly ignored in many analytical works in literature. Furthermore, the femtocells employ a sensing algorithm to minimize spectrum sharing with macro users in close proximity, especially at the transition areas of center and edge region where cross-tier interference could be monumental. Numerical simulations are used to evaluate performance of the proposed framework in terms of coverage probability and average user rate, and results are compared with traditional FFR schemes and the No-FFR deployment. To the best of the author's knowledge, this is the first analytical framework characterizing sectored-FFR schemes using stochastic geometry tools in Hetnets.