Linearization of High Power Amplifier Using A Memristor in Microwave Transmission

Abstract

The transmission of high-power signals via terrestrial or satellite media requires High Power Amplifiers (HPAs) to amplify these signals over a long range. High power amplifiers are used primarily to ensure effectiveness and efficiency in the transmission as well as to boost the signal to a sufficient power level for transmission to supply the receiver with a sufficiently high level of signal power. The most popular HPA's include Travelling Wave Tube amplifier (TWTA), Klystron Power Amplifiers, Solid State Power Amplifiers (SSPA), etc. Distortion is the creation of unwanted signals at frequencies the original signal does not contain. Hence, distortion is produced by a loss of linearity. The transmission of signals has been upgraded to higher levels over the years requiring the extensive use of more sophisticated modulation techniques such as Quadrature Amplitude Modulation (QAM) and other algorithms to handle the huge data demands of our modern society. In microwave satellite transmission, a High Power Amplifier (HPA) known as Travelling Wave Tube Amplifier (TWTA) is usually used to drive the carrier signal to the receiver. The problem of non-linearity arises when the HPA is operated close to its maximum power resulting in distortion of the carrier signal, thus reduction in efficiency. This paper presents the design of linearization of HPA using memory resistance predistorter to linearize the output of HPA. The output signal suffers from non-linearity distortions so memristor has been proposed a predistorter for HPA output linearization. The parameter used in modelling the input signal is 1 V, 3 GHz RF 64 QAM signal, initial memory resistance of 30 $\Omega,$ Dopant drift mobility constant of 104, and the difference between boundary resistances is $7.5 \pi M\Omega$. The result obtained was a linearized HPA voltage with 98% efficiency.