Linearization of asymmetrical two-way Doherty amplifier

Linearization of two-way Doherty amplifier by injection of second and forth order nonlinear signals at the input and output of the carrier cell

“…However, IM5 products increase slightly at the whole power range considered, though IM5 products are kept at the power level close to the linearized IM3 products. According to the theoretical analysis of the linearization approach ( [5]), IM2 and IM4 signals can reduce both IM3 and IM5 products that depends on the relations between amplitudes as well as phases of the IM2 and IM4 signals generated at the peaking amplifier output. Nevertheless, when the required relations are not fulfilled, only one kind of the intermodulation products can be reduced sufficiently.…”

“…Theoretical analysis of the linearization approach that uses the second harmonics and fourth-order nonlinear signals (IM2 and IM4) for linearization has been given in [5], and [7]. According to this, it is possible to reduce spectral re-growth caused by the third-order distortion of fundamental signal by choosing the appropriate amplitude and phase of IM2 signals injected at the input and output of the amplifier.…”

“…The IM2 and IM4 signals generated at the output of peaking amplifier are extracted through the frequency diplexer circuit in configuration depicted in [5]. It separates the fundamental signals and signals for linearization (IM2 and IM4 signals) that are matched to the impedance for their adequate power level.…”

“…Serbia, Nis, October 5 -8, 2011 Two-way Doherty amplifier was designed in standard configuration [1], [2], [4], [5]. The second harmonics, IM2, and fourth-order nonlinear signals at frequencies close to the second harmonics, IM4, which are generated at the output of the peaking amplifier, are extracted through the diplexer circuit.…”

“…We applied the approach where IM2 and IM4 signals are injected together with the fundamental signals into the carrier amplifier input and put at its output [7]. Additionally, the influence of IM2 and IM4 signals on Doherty amplifier linearity was verified experimentally on standard two-way Doherty amplifier in two cases: when linearization signals are led to the input of carrier cell [8] and when they are injected at the output of carrier cell [9].…”