Improvement in second harmonics linearization technique for multichannel amplifiers

Abstract

A linearization technique that uses the injection of the

Linearization of power amplifiers by second harmonics and fourth‐order nonlinear signals

“…A basic concept of the linearization technique that uses the injection of the second harmonics (IM2 signals) at the amplifier input has accomplished promising results in the reduction of third‐order intermodulation products (IM3) up to the lower power of fundamental signals, as reported in Refs. 1–4. For a higher power of fundamental signals, the encouraging results in the IM3 decrease have been obtained through the simulation process by applying the simultaneous injection of the second harmonics into the amplifier input and output, as described in Ref 5…”

Linearization of Multichannel Amplifiers Close to Saturation with Improved Efficiency

“…The influences of fundamental signals' second harmonics (denoted as IM2 signals) to the third-order intermodulation products (IM3) in microwave power amplifiers have been investigated and applied in [1]- [4]. The basic concept of the linearization technique with the injection of IM2 signals gives good results in reduction of the IM3 products up to the certain power of the fundamental signals that depends on load impedance [3].…”

The Linearization of Two Multichannel Amplifiers Connected in Cascade by Using the Second Harmonics and Fourth-Order Nonlinear Signals

“…At higher power levels of the input signals the hm3 terms raise the IM3 products. Therefore, in case when the linearization is carried out by the injection of IM2 signals at the input of a single amplifier [1][2][3] the tuning of IM2 signals cannot reduce IM3 products. This is conditioned by the fact that the hm3 terms depend on differences between phases of the IM2 signals, which can not be controlled when signals are injected over the same injection path.…”

“…The terms expressed by Eq. (3) are generated by mixing the fundamental signal and two IM2 signals which are either got at the output of the first amplifier or generated at the output of IM2+IM4 source. Moreover, Eq.…”

“…The second harmonics and products at frequencies that are the sum of pairs of the fundamental signal frequencies (altogether denoted as IM2 signals) have been injected into the amplifier in order to reduce the third-order intermodulation products, IM3 [1][2][3]. The linearizatoin has been attained by adjusting the amplitudes and phases of the IM2 signals on the optimal values.…”