Analyzing LINC Systems

RF Spatial Modulation Using Antenna Arrays

“…Since and are constant envelope signals, they can be amplified by highly efficient nonlinear amplifiers. The constant envelope signals and occupy a larger bandwidth than the original signal S(t) [15]. The linearity of the combined output is determined by the gain and phase match performance of the two amplification channels.…”

“…1 and 2, the constant envelope signals are amplified with nonlinear high efficiency amplifiers and combined with a passive combiner [13]- [15]. Therefore, the efficiencies of LINC and AOM depend on not only the amplifier efficiency, but also the combiner efficiency.…”

“…Therefore, the efficiencies of LINC and AOM depend on not only the amplifier efficiency, but also the combiner efficiency. The efficiencies of LINC [15] and AOM can be expressed as (8) where is the efficiency of LINC or AOM, and are the efficiencies of amplifier and combiner respectively. Both isolated and nonisolated combiners can realize power combination [14]- [17].…”

“…The in-phase signal components are added in the output and the out-of-phase signal components are dissipated in the isolation load of the isolated combiner. The combiner efficiency can be expressed as [15] (9) and the average efficiency of LINC is [15] (10)…”

“…With multiple constant envelop signals, the PDF of (t) in large value is reduced, thus the average efficiency can be increased. The Chireix combiner is a kind of nonisolated combiner, which has higher average efficiency compared with the isolation combiner, but the interaction between the amplifiers degrades the linearity of the combined signal [14], [15].…”